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Fragola NR, Brems BM, Mukherjee M, Cui M, Booth RG. Conformationally Selective 2-Aminotetralin Ligands Targeting the alpha2A- and alpha2C-Adrenergic Receptors. ACS Chem Neurosci 2023; 14:1884-1895. [PMID: 37104867 PMCID: PMC10628895 DOI: 10.1021/acschemneuro.3c00148] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Many important physiological processes are mediated by alpha2A- and alpha2C-adrenergic receptors (α2Rs), a subtype of class A G protein-coupled receptors (GPCRs). However, α2R signaling is poorly understood, and there are few approved medications targeting these receptors. Drug discovery aimed at α2Rs is complicated by the high degree of binding pocket homology between α2AR and α2CR, which confounds ligand-mediated selective activation or inactivation of signaling associated with a particular subtype. Meanwhile, α2R signaling is complex and it is reported that activating α2AR is beneficial in many clinical contexts, while activating α2CR signaling may be detrimental to these positive effects. Here, we report on a novel 5-substituted-2-aminotetralin (5-SAT) chemotype that, depending on substitution, has diverse pharmacological activities at α2Rs. Certain lead 5-SAT analogues act as partial agonists at α2ARs, while functioning as inverse agonists at α2CRs, a novel pharmacological profile. Leads demonstrate high potency (e.g., EC50 < 2 nM) at the α2AR and α2CRs regarding Gαi-mediated inhibition of adenylyl cyclase and production of cyclic adenosine monophosphate (cAMP). To help understand the molecular basis of 5-SAT α2R multifaceted functional activity, α2AR and α2CR molecular models were built from the crystal structures and 1 μs molecular dynamics (MD) simulations and molecular docking experiments were performed for a lead 5-SAT with α2AR agonist and α2CR inverse agonist activity, i.e., (2S)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (FPT), in comparison to the FDA-approved (for opioid withdrawal symptoms) α2AR/α2CR agonist lofexidine. Results reveal several interactions between FPT and α2AR and α2CR amino acids that may impact the functional activity. The computational data in conjunction with experimental in vitro affinity and function results provide information to understand ligand stabilization of functionally distinct GPCR conformations regarding α2AR and α2CRs.
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Affiliation(s)
- Nicholas R. Fragola
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry
& Chemical Biology, Northeastern University, 208, Mugar Life Sciences Building, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Brittany M. Brems
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry
& Chemical Biology, Northeastern University, 208, Mugar Life Sciences Building, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Munmun Mukherjee
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry
& Chemical Biology, Northeastern University, 208, Mugar Life Sciences Building, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Meng Cui
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry
& Chemical Biology, Northeastern University, 208, Mugar Life Sciences Building, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Raymond G. Booth
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry
& Chemical Biology, Northeastern University, 208, Mugar Life Sciences Building, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
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The α 2C-adrenoceptor antagonist JP-1302 controls behavioral parameters, tyrosine hydroxylase activity and receptor expression in a rat model of ketamine-induced schizophrenia-like deficits. Pharmacol Biochem Behav 2022; 221:173490. [PMID: 36379444 DOI: 10.1016/j.pbb.2022.173490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
Schizophrenia is a chronic disabling disease affecting 1 % of the population. Current antipsychotics have limited efficacy in mitigating the severity of the symptoms of the disease. Therefore, searching for new therapeutic targets is essential. Previous studies have shown that α2C-adrenoceptor antagonists may have antipsychotic and pro-cognitive effects. Therefore, the current study evaluates the behavioral and neurochemical effects of JP-1302, a selective α2C-adrenoceptor antagonist, in a model of schizophrenia-like deficits induced by sub-chronic ketamine (KET) administration. Here, we administered ketamine (25 mg/kg, i.p.) to male and female Wistar rats for eight consecutive days. On the last two days of ketamine administration, rats were pretreated with either JP-1302 (1-3-10 μmol/kg, i.p.), chlorpromazine (0.1 mg/kg, i.p.), or saline, and the behavioral tests were performed. Behaviors related to positive (locomotor activity), negative (social interaction), and cognitive (novel object recognition) symptoms of schizophrenia were assessed. Glutamate, glutamine, GABA levels, and α2C-adrenoceptor expression were measured in the frontal cortex and the hippocampus. Tyrosine hydroxylase immunocytochemical reactivity was also shown in the midbrain regions. Sub-chronic ketamine administration increased locomotor activity and produced robust social interaction and object recognition deficits, and JP-1302 significantly ameliorated ketamine-induced cognitive deficits. Ketamine induced a hyperdopaminergic activity in the striatum, which was reversed by the treatment with JP-1302. Also, the α2C-adrenoceptor expression was higher in the frontal cortex and hippocampus in the ketamine-treated rats. Our findings confirm that α2C-adrenoceptor antagonism may be a potential drug target for treating cognitive disorders related to schizophrenia.
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van der Goot MH, Kooij M, Stolte S, Baars A, Arndt SS, van Lith HA. Incorporating inter-individual variability in experimental design improves the quality of results of animal experiments. PLoS One 2021; 16:e0255521. [PMID: 34351958 PMCID: PMC8341614 DOI: 10.1371/journal.pone.0255521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/16/2021] [Indexed: 11/19/2022] Open
Abstract
Inter-individual variability in quantitative traits is believed to potentially inflate the quality of results in animal experimentation. Yet, to our knowledge this effect has not been empirically tested. Here we test whether inter-individual variability in emotional response within mouse inbred strains affects the outcome of a pharmacological experiment. Three mouse inbred strains (BALB/c, C57BL/6 and 129S2) were behaviorally characterized through repeated exposure to a mild aversive stimulus (modified Hole Board, five consecutive trials). A multivariate clustering procedure yielded two multidimensional response types which were displayed by individuals of all three strains. We show that systematic incorporation of these individual response types in the design of a pharmacological experiment produces different results from an experimental pool in which this variation was not accounted for. To our knowledge, this is the first study that empirically confirms that inter-individual variability affects the interpretation of behavioral phenotypes and may obscure experimental results in a pharmacological experiment.
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Affiliation(s)
- Marloes H. van der Goot
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Marieke Kooij
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Suzanne Stolte
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Annemarie Baars
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Saskia S. Arndt
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Hein A. van Lith
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
- Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands
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Zhou C, Guo T, Wu J, Wang L, Bai X, Gao T, Guan X, Gu L, Huang P, Xuan M, Gu Q, Xu X, Zhang B, Cheng W, Feng J, Zhang M. Locus Coeruleus Degeneration Correlated with Levodopa Resistance in Parkinson's Disease: A Retrospective Analysis. JOURNAL OF PARKINSONS DISEASE 2021; 11:1631-1640. [PMID: 34366373 PMCID: PMC8609680 DOI: 10.3233/jpd-212720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background: The widely divergent responsiveness of Parkinson’s disease (PD) patients to levodopa is an important clinical issue because of its relationship with quality of life and disease prognosis. Preliminary animal experiments have suggested that degeneration of the locus coeruleus (LC) attenuates the efficacy of levodopa treatment. Objective: To explore the relationship between LC degeneration and levodopa responsiveness in PD patients in vivo. Methods: Neuromelanin-sensitive magnetic resonance imaging (NM-MRI), a good indicator of LC and substantia nigra (SN) degeneration, and levodopa challenge tests were conducted in 57 PD patients. Responsiveness to levodopa was evaluated by the rates of change of the Unified Parkinson’s Disease Rating Scale Part III score and somatomotor network synchronization calculated from resting-state functional MRI before and after levodopa administration. Next, we assessed the relationship between the contrast-to-noise ratio of LC (CNRLC) and levodopa responsiveness. Multiple linear regression analysis was conducted to rule out the potential influence of SN degeneration on levodopa responsiveness. Results: A significant positive correlation was found between CNRLC and the motor improvement after levodopa administration (R = 0.421, p = 0.004). CNRLC also correlated with improvement in somatomotor network synchronization (R = –0.323, p = 0.029). Furthermore, the relationship between CNRLC and levodopa responsiveness was independent of SN degeneration. Conclusion: LC degeneration might be an essential factor for levodopa resistance. LC evaluation using NM-MRI might be an alternative tool for predicting levodopa responsiveness and for helping to stratify patients into clinical trials aimed at improving the efficacy of levodopa.
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Affiliation(s)
- Cheng Zhou
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Tao Guo
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - JingJing Wu
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Linbo Wang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Xueqin Bai
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ting Gao
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaojun Guan
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Luyan Gu
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Peiyu Huang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Min Xuan
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Quanquan Gu
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaojun Xu
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Baorong Zhang
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Cheng
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Jianfeng Feng
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China.,Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai, China.,Department of Computer Science, University of Warwick, Coventry, United Kingdom
| | - Minming Zhang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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The Effect of Early Sedation With Dexmedetomidine on Body Temperature in Critically Ill Patients. Crit Care Med 2021; 49:1118-1128. [PMID: 33729724 DOI: 10.1097/ccm.0000000000004935] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Previous case series reported an association between dexmedetomidine use and hyperthermia. Temperature data have not been systematically reported in previous randomized controlled trials evaluating dexmedetomidine. A causal link between dexmedetomidine administration and elevated temperature has not been demonstrated. DESIGN Post hoc analysis. SETTING Four ICUs in Australia and New Zealand. PATIENTS About 703 mechanically ventilated ICU patients. INTERVENTIONS Early sedation with dexmedetomidine versus usual care. MEASUREMENTS AND MAIN RESULTS The primary outcome was mean daily body temperature. Secondary outcomes included the proportions of patients with body temperatures greater than or equal to 38.3°C and greater than or equal to 39°C, respectively. Outcomes were recorded for 5 days postrandomization in the ICU. The mean daily temperature was not different between the dexmedetomidine (n = 351) and usual care (n = 352) groups (36.84°C ± sd vs 36.78°C ± sd; p = 0.16). Over the first 5 ICU days, more dexmedetomidine group (vs usual care) patients had a temperature greater than or equal to 38.3°C (43.3% vs 32.7%, p = 0.004; absolute difference 10.6 percentage points) and greater than or equal to 39.0°C (19.4% vs 12.5%, p = 0.013; absolute difference 6.9 percentage points). Results were similar after adjusting for diagnosis, admitting temperature, age, weight, study site, sepsis occurrence, and the time from dexmedetomidine initiation to first hyperthermia recorded. There was a significant dose response relationship with temperature increasing by 0.30°C ±0.08 for every additional 1 μg/kg/hr of dexmedetomidine received p < 0.0002. CONCLUSIONS Our study suggests potentially important elevations in body temperature are associated with early dexmedetomidine sedation, in adults who are mechanically ventilated in the ICU.
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Harvey BH, Uys MM, Viljoen FP, Shahid M, Sonntag Q, Meyer LCR. Hippocampal monoamine changes in the Flinders sensitive line rat: A case for the possible use of selective α 2C-AR-antagonists in stress and anxiety disorders in companion animals. Res Vet Sci 2021; 135:175-183. [PMID: 33529845 DOI: 10.1016/j.rvsc.2021.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 01/12/2021] [Accepted: 01/21/2021] [Indexed: 12/21/2022]
Abstract
Non-selective α2-adrenoreceptor (AR) stimulation delivers favourable sedative, analgesic, muscle relaxant and anxiolytic actions in companion animals, but is associated with cardiovascular and respiratory side effects. Anxiety conditions underscore monoamine disturbances amenable to α2-AR modulation. We investigated sub-chronic (14 day s.c.) treatment with the selective α2C-AR antagonist, ORM-10921 (0.03, 0.1, 0.3 mg/kg/d) on hippocampal noradrenaline (NA), dopamine (DA), serotonin (5-HT) and their turnover levels in stress sensitive Flinders Sensitive Line (FSL) rats versus Flinders Resistant Line (FRL) controls, using high performance liquid chromatography. The effects of ORM-10921 were compared to the non-selective α2-AR antagonist, idazoxan (IDAZ; 3 mg/kg/d), and to imipramine (IMI; 15 mg/kg/d), a reference antidepressant in this model. FSL rats displayed significantly reduced 5-HT (p = 0.03) and DA (p = 0.02) levels vs. FRL controls, while NA levels showed a similar trend. ORM-10921 significantly increased NA (all doses p ≤ 0.02), 5-HT (0.1 and 0.3 mg/kg p ≤ 0.03) and DA levels (all doses p ≤ 0.03), which correlated with decreased monoamine turnover. In contrast, IDAZ significantly elevated NA (p < 0.005) and DA (p < 0.004) but not 5-HT levels. IMI also significantly increased 5-HT (p < 0.009), with a tendency to increase NA (p = 0.09) but not DA. ORM-10921 exerts similar albeit broader effects on hippocampal monoamines than IDAZ, explaining earlier established efficacy associated with α2C-AR antagonism in animal models of depression and cognitive dysfunction. These and the current studies encourage application of ORM-10921 in depression in humans, as well as raise the intriguing possibility that selective α2C-AR antagonists may be beneficial in anxiety and stress-related disorders in companion animals. Both warrant further study.
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Affiliation(s)
- Brian H Harvey
- Division of Pharmacology, Center of Excellence for Pharmaceutical Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa; South African MRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa.
| | - Madeleine M Uys
- Division of Pharmacology, Center of Excellence for Pharmaceutical Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
| | - Francois P Viljoen
- Division of Pharmacology, Center of Excellence for Pharmaceutical Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
| | | | - Quixi Sonntag
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Leith C R Meyer
- Centre for Veterinary Wildlife Studies and Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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Pandit J, O'Donohoe P, Turner P, Huskens N, Buckler K. Lack of influence of dexmedetomidine on rat glomus cell response to hypoxia, and on mouse acute hypoxic ventilatory response. J Anaesthesiol Clin Pharmacol 2021; 37:509-516. [PMID: 35340947 PMCID: PMC8944378 DOI: 10.4103/joacp.joacp_309_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 11/05/2022] Open
Abstract
Background and Aims: There is a lack of basic science data on the effect of dexmedetomidine on the hypoxic chemosensory reflex with both depression and stimulation suggested. The primary aim of this study was to assess if dexmedetomidine inhibited the cellular response to hypoxia in rat carotid body glomus cells, the cells of the organs mediating acute hypoxic ventilatory response (AHVR). Additionally, we used a small sample of mice to assess if there was any large influence of subsedative doses of dexmedetomidine on AHVR. Material and Methods: In the primary study, glomus cells isolated from neonatal rats were used to study the effect of 0.1 nM (n = 9) and 1 nM (n = 13) dexmedetomidine on hypoxia-elicited intracellular calcium [Ca2%]i influx using ratiometric fluorimetry. Secondarily, whole animal unrestrained plethysmography was used to study AHVR in a total of 8 age-matched C57BL6 mice, divided on successive days into two groups of four mice randomly assigned to receive sub-sedative doses of 5, 50, or 500 μg.kg-1 dexmedetomidine versus control in a crossover study design (total n = 12 exposures to drug with n = 12 controls). Results: There was no effect of dexmedetomidine on the hypoxia-elicited increase in [Ca2%]i in glomus cells (a mean ± SEM increase of 95 ± 32 nM from baseline with control hypoxia, 124 ± 41 nM with 0.1 nM dexmedetomidine; P = 0.514). In intact mice, dexmedetomidine had no effect on baseline ventilation during air-breathing (4.01 ± 0.3 ml.g-1.min-1 in control and 2.99 ± 0.5 ml.g-1.min-1 with 500 μg.kg-1 dexmedetomidine, the highest dose; P = 0.081) or on AHVR (136 ± 19% increase from baseline in control, 152 ± 46% with 500 μg.kg-1 dexmedetomidine, the highest dose; P = 0.536). Conclusion: Dexmedetomidine had no effect on the cellular responses to hypoxia. We conclude that it unlikely acts via inhibition of oxygen sensing at the glomus cell. The respiratory chemoreflex effects of this drug remain an open question. In our small sample of intact mice, hypoxic chemoreflex responses and basal breathing were preserved.
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Pharmacological screening of a new alpha-2 adrenergic receptor agonist, mafedine, in zebrafish. Neurosci Lett 2019; 701:234-239. [PMID: 30836120 DOI: 10.1016/j.neulet.2019.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 02/25/2019] [Accepted: 03/02/2019] [Indexed: 10/27/2022]
Abstract
Pharmacological agents acting at alpha-2 adrenergic receptors are widely used in physiology and neuroscience research. Mounting evidence of their potential utility in clinical and experimental psychopharmacology, necessitates new models and novel model organisms for their screening. Here, we characterize behavioral effects of mafedine (6-oxo-1-phenyl-2- (phenylamino)-1,6-dihydropyrimidine-4-sodium olate), a novel drug with alpha-2 adrenergic receptor agonistic effects, in adult zebrafish (Danio rerio) in the novel tank test of anxiety and activity. Following an acute 20-min exposure, mafedine at 60 mg/L produced a mild psychostimulant action with some anxiogenic-like effects. Repeated acute 20-min/day administration of mafedine for 7 consecutive days at 1, 5 and 10 mg/L had a similar action on fish behavior as an acute exposure to 60 mg/L. Since mafedine demonstrated robust behavioral effects in zebrafish - a sensitive vertebrate aquatic model, it is likely that it may modulate rodent and human behavior as well. Thus, further studies are needed to explore this possibility in detail, and whether it may foster clinical application of mafedine and related alpha-2 adrenergic agents.
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The association of an alpha2C adrenoreceptor gene polymorphism with vasomotor symptoms in African American women. Menopause 2018; 26:300-305. [PMID: 30277919 DOI: 10.1097/gme.0000000000001218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The alpha2C adrenoreceptor deletion 322-325 (ADRA2C del 322-325) polymorphism has been associated with autonomic activity and thermoregulation, which are implicated in the vasomotor symptom (VMS) mechanism. The ADRA2C del (322-325) has higher prevalence in African American women, a group known to experience more frequent and bothersome VMS. We assessed whether the ADRA2C del (322-325) genotype is associated with increased frequency of VMS in African American women. METHODS DNA samples from African American (N = 400) women participating in the Study of Women's Health Across the Nation (SWAN) were genotyped for the ADRA2C del (322-325) polymorphism. Longitudinal data on VMS were obtained from the SWAN repository. The relation of ADRA2C del (322-325) genotypes (deletion/deletion [D/D]; insertion/deletion [I/D]; insertion/insertion [I/I]) with VMS over the menopausal transition for up to 12 years of follow-up was examined using generalized estimating equations. Primary models considered the outcome of frequent VMS (6 or more days in the prior 2 wk vs VMS <6 d in the prior 2 wk) by stage of menopause. RESULTS Four hundred DNA samples from African American women were included. Seventy-five women (18.8%) were found to carry the homozygous variant allele (D/D). There was no significant difference in the trajectory of frequent VMS over the menopausal transition between women with D/D and I/I + I/D genotypes (P = 0.39). CONCLUSIONS In this preliminary study among African American women in SWAN, ADRA2C del (322-325) was not significantly related to self-reported VMS. Further studies are warranted to help us understand the role of the adrenergic system in the physiology of VMS to tailor medical therapy to patient needs.
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Abstract
Although serotonin neurotransmission has been implicated in several neurodevelopmental and psychological disorders, the factors that drive dysfunction of the serotonin system are poorly understood. Current research regarding the serotonin system revolves around its dysfunction in neuropsychiatric disorders, but there is no database collating genetic mutations that result in serotonin abnormalities. To bridge this gap, we developed a list of genes in mice that, when perturbed, result in altered levels of serotonin either in brain or blood. Due to the intrinsic limitations of search, the current list should be considered a preliminary subset of all relevant cases. Nevertheless, it offered an opportunity to gain insight into what types of genes have the potential to impact serotonin by using gene ontology (GO). This analysis found that genes associated with monoamine metabolism were more often associated with increases in brain serotonin than decreases. Speculatively, this could be because several pathways (and therefore many genes) are responsible for the clearance and metabolism of serotonin whereas only one pathway (and therefore fewer genes) is directly involved in the synthesis of serotonin. Another contributor could be cross talk between monoamine systems such as dopamine. In contrast, genes that were associated with decreases in brain serotonin were more likely linked to a developmental process. Sensitivity of serotonin neurons to developmental perturbations could be due to their complicated neuroanatomy or possibly they may be negatively regulated by dysfunction of their innervation targets. Thus, these observations suggest hypotheses regarding the mechanisms underlying the vulnerability of brain serotonin neurotransmission.
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Affiliation(s)
- Richard C. Tenpenny
- Department of Anesthesiology, Perioperative, and Pain
Medicine, Boston Children’s Hospital and Department of Anesthesia,
Harvard Medical School, 300 Longwood
Avenue, Boston, Massachusetts 02115, United States
| | - Kathryn G. Commons
- Department of Anesthesiology, Perioperative, and Pain
Medicine, Boston Children’s Hospital and Department of Anesthesia,
Harvard Medical School, 300 Longwood
Avenue, Boston, Massachusetts 02115, United States
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Uys MM, Shahid M, Harvey BH. Therapeutic Potential of Selectively Targeting the α 2C-Adrenoceptor in Cognition, Depression, and Schizophrenia-New Developments and Future Perspective. Front Psychiatry 2017; 8:144. [PMID: 28855875 PMCID: PMC5558054 DOI: 10.3389/fpsyt.2017.00144] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 07/24/2017] [Indexed: 12/12/2022] Open
Abstract
α2A- and α2C-adrenoceptors (ARs) are the primary α2-AR subtypes involved in central nervous system (CNS) function. These receptors are implicated in the pathophysiology of psychiatric illness, particularly those associated with affective, psychotic, and cognitive symptoms. Indeed, non-selective α2-AR blockade is proposed to contribute toward antidepressant (e.g., mirtazapine) and atypical antipsychotic (e.g., clozapine) drug action. Both α2C- and α2A-AR share autoreceptor functions to exert negative feedback control on noradrenaline (NA) release, with α2C-AR heteroreceptors regulating non-noradrenergic transmission (e.g., serotonin, dopamine). While the α2A-AR is widely distributed throughout the CNS, α2C-AR expression is more restricted, suggesting the possibility of significant differences in how these two receptor subtypes modulate regional neurotransmission. However, the α2C-AR plays a more prominent role during states of low endogenous NA activity, while the α2A-AR is relatively more engaged during states of high noradrenergic tone. Although augmentation of conventional antidepressant and antipsychotic therapy with non-selective α2-AR antagonists may improve therapeutic outcome, animal studies report distinct yet often opposing roles for the α2A- and α2C-ARs on behavioral markers of mood and cognition, implying that non-selective α2-AR antagonism may compromise therapeutic utility both in terms of efficacy and side-effect liability. Recently, several highly selective α2C-AR antagonists have been identified that have allowed deeper investigation into the function and utility of the α2C-AR. ORM-13070 is a useful positron emission tomography ligand, ORM-10921 has demonstrated antipsychotic, antidepressant, and pro-cognitive actions in animals, while ORM-12741 is in clinical development for the treatment of cognitive dysfunction and neuropsychiatric symptoms in Alzheimer's disease. This review will emphasize the importance and relevance of the α2C-AR as a neuropsychiatric drug target in major depression, schizophrenia, and associated cognitive deficits. In addition, we will present new prospects and future directions of investigation.
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Affiliation(s)
- Madeleine Monique Uys
- Division of Pharmacology, Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
| | | | - Brian Herbert Harvey
- Division of Pharmacology, Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
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Fardoun MM, Nassif J, Issa K, Baydoun E, Eid AH. Raynaud's Phenomenon: A Brief Review of the Underlying Mechanisms. Front Pharmacol 2016; 7:438. [PMID: 27899893 PMCID: PMC5110514 DOI: 10.3389/fphar.2016.00438] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/03/2016] [Indexed: 11/28/2022] Open
Abstract
Raynaud’s phenomenon (RP) is characterized by exaggerated cold-induced vasoconstriction. This augmented vasoconstriction occurs by virtue of a reflex response to cooling via the sympathetic nervous system as well as by local activation of α2C adrenoceptors (α2C-AR). In a cold-initiated, mitochondrion-mediated mechanism involving reactive oxygen species and the Rho/ROCK pathway, cytoskeletal rearrangement in vascular smooth muscle cells orchestrates the translocation of α2C-AR to the cell membrane, where this receptor readily interacts with its ligand. Different parameters are involved in this spatial and functional rescue of α2C-AR. Of notable relevance is the female hormone, 17β-estradiol, or estrogen. This is consistent with the high prevalence of RP in premenopausal women compared to age-matched males. In addition to dissecting the role of these various players, the contribution of pollution as well as genetic background to the onset and prevalence of RP are also discussed. Different therapeutic approaches employed as treatment modalities for this disease are also highlighted and analyzed. The lack of an appropriate animal model for RP mandates that more efforts be undertaken in order to better understand and eventually treat this disease. Although several lines of treatment are utilized, it is important to note that precaution is often effective in reducing severity or frequency of RP attacks.
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Affiliation(s)
- Manal M Fardoun
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut Beirut, Lebanon
| | - Joseph Nassif
- Department of Obstetrics and Gynecology, Faculty of Medicine, American University of Beirut Beirut, Lebanon
| | - Khodr Issa
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut Beirut, Lebanon
| | - Elias Baydoun
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut Beirut, Lebanon
| | - Ali H Eid
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut Beirut, Lebanon
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Zaniewska M, Filip M, Przegalinski E. The Involvement of Norepinephrine in Behaviors Related to Psychostimulant Addiction. Curr Neuropharmacol 2016; 13:407-18. [PMID: 26411968 PMCID: PMC4812804 DOI: 10.2174/1570159x13666150121225659] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although it is generally accepted that the abuse-related effects of
amphetamines and cocaine result from the activation of the brain dopaminergic
(DA) system, the psychostimulants also alter other neurotransmitter systems. In
particular, they increase extracellular levels of norepinephrine (NE) and
serotonin by inhibiting respective plasma membrane transporters and/or inducing
release. The present review will discuss the preclinical findings on the effects
of the NE system modulation (lesions, pharmacological and genetic approaches) on
behaviors (locomotor hyperactivity, behavioral sensitization, modification of
intracranial self-stimulation, conditioned place preference, drug
self-administration, extinction/reinstatement of drug seeking behavior) related
to the psychostimulant addiction.
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Affiliation(s)
- Magdalena Zaniewska
- Laboratory of Drug Addiction Pharmacology, Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland.
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Pan W, Hua X, Wang Y, Guo R, Chen J, Mo L. Dose response of dexmedetomidine-induced resistance to hypoxia in mice. Mol Med Rep 2016; 14:3237-42. [DOI: 10.3892/mmr.2016.5588] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 06/09/2016] [Indexed: 11/06/2022] Open
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Rivero G, Martín-Guerrero I, de Prado E, Gabilondo AM, Callado LF, García-Sevilla JA, García-Orad Á, Meana JJ. Alpha2C-adrenoceptor Del322-325 polymorphism and risk of psychiatric disorders: significant association with opiate abuse and dependence. World J Biol Psychiatry 2016; 17:308-15. [PMID: 27007576 DOI: 10.3109/15622975.2016.1142608] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Objectives α2C-adrenoceptors (α2C-AR) are involved in behavioural responses relevant to psychiatric disorders and suicide completion. The genetic polymorphism α2CDel322-325-AR confers a loss-of-function phenotype. Functional human studies have associated α2CDel322-325-AR polymorphism with major depression pathophysiology. The aim of this study was to analyse, for the first time, the association of α2CDel322-325-AR polymorphism with suicide completion and with related psychiatric disorders: major depression, schizophrenia, opiate and alcohol abuse and dependence. Methods Post-mortem brain DNA was extracted (n = 516) and genotyping performed by HaeIII restriction endonuclease digestion of PCR products and DNA fragment analysis on capillary sequencer. Amplified products were sequenced to confirm the presence of the polymorphism. Results The frequency of α2CDel322-325-AR in suicide (9%, n = 236) and non-suicide victims (11%, n = 280) was similar. Genotype frequencies for the α2CDel322-325-AR polymorphism in depressed (15%, n = 39) and schizophrenic subjects (18%, n = 39) were higher than in controls (7%, n = 187), but these differences did not reach statistical significance (P = 0.125 and P = 0.063, respectively). A selective and significant association of α2CDel322-325-AR polymorphism with opiate abuse and dependence was found (23%, n = 35, P = 0.011). Conclusions Our results indicate that α2CDel322-325-AR may play a role in the pathophysiology of opiate abuse and dependence and raise the interest for larger genetic associative studies.
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Affiliation(s)
- Guadalupe Rivero
- a Department of Pharmacology , University of the Basque Country (UPV/EHU) and Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Spain ;,c BioCruces Health Research Institute , Spain
| | - Idoia Martín-Guerrero
- b Department of Genetics, Physical Anthropology and Animal Physiology , University of the Basque Country (UPV/EHU) , Spain ;,c BioCruces Health Research Institute , Spain
| | - Elena de Prado
- b Department of Genetics, Physical Anthropology and Animal Physiology , University of the Basque Country (UPV/EHU) , Spain ;,c BioCruces Health Research Institute , Spain
| | - Ane M Gabilondo
- a Department of Pharmacology , University of the Basque Country (UPV/EHU) and Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Spain ;,c BioCruces Health Research Institute , Spain
| | - Luis F Callado
- a Department of Pharmacology , University of the Basque Country (UPV/EHU) and Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Spain ;,c BioCruces Health Research Institute , Spain
| | - Jesús A García-Sevilla
- d Laboratory of Neuropharmacology , IUNICS-IdISPa, University of the Balearic Islands (UIB), and Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA) , Spain
| | - África García-Orad
- b Department of Genetics, Physical Anthropology and Animal Physiology , University of the Basque Country (UPV/EHU) , Spain ;,c BioCruces Health Research Institute , Spain
| | - J Javier Meana
- a Department of Pharmacology , University of the Basque Country (UPV/EHU) and Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) , Spain ;,c BioCruces Health Research Institute , Spain
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Abstract
Physical challenges, emotional arousal, increased physical activity, or changes in the environment can evoke stress, requiring altered activity of visceral organs, glands, and smooth muscles. These alterations are necessary for the organism to function appropriately under these abnormal conditions and to restore homeostasis. These changes in activity comprise the "fight-or-flight" response and must occur rapidly or the organism may not survive. The rapid responses are mediated primarily via the catecholamines, epinephrine, and norepinephrine, secreted from the adrenal medulla. The catecholamine neurohormones interact with adrenergic receptors present on cell membranes of all visceral organs and smooth muscles, leading to activation of signaling pathways and consequent alterations in organ function and smooth muscle tone. During the "fight-or-flight response," the rise in circulating epinephrine and norepinephrine from the adrenal medulla and norepinephrine secreted from sympathetic nerve terminals cause increased blood pressure and cardiac output, relaxation of bronchial, intestinal and many other smooth muscles, mydriasis, and metabolic changes that increase levels of blood glucose and free fatty acids. Circulating catecholamines can also alter memory via effects on afferent sensory nerves impacting central nervous system function. While these rapid responses may be necessary for survival, sustained elevation of circulating catecholamines for prolonged periods of time can also produce pathological conditions, such as cardiac hypertrophy and heart failure, hypertension, and posttraumatic stress disorder. In this review, we discuss the present knowledge of the effects of circulating catecholamines on peripheral organs and tissues, as well as on memory in the brain.
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Affiliation(s)
- A William Tank
- Department of Pharmacology & Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Dona Lee Wong
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, MA, USA
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Finnema SJ, Scheinin M, Shahid M, Lehto J, Borroni E, Bang-Andersen B, Sallinen J, Wong E, Farde L, Halldin C, Grimwood S. Application of cross-species PET imaging to assess neurotransmitter release in brain. Psychopharmacology (Berl) 2015; 232:4129-57. [PMID: 25921033 PMCID: PMC4600473 DOI: 10.1007/s00213-015-3938-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/09/2015] [Indexed: 01/03/2023]
Abstract
RATIONALE This review attempts to summarize the current status in relation to the use of positron emission tomography (PET) imaging in the assessment of synaptic concentrations of endogenous mediators in the living brain. OBJECTIVES Although PET radioligands are now available for more than 40 CNS targets, at the initiation of the Innovative Medicines Initiative (IMI) "Novel Methods leading to New Medications in Depression and Schizophrenia" (NEWMEDS) in 2009, PET radioligands sensitive to an endogenous neurotransmitter were only validated for dopamine. NEWMEDS work-package 5, "Cross-species and neurochemical imaging (PET) methods for drug discovery", commenced with a focus on developing methods enabling assessment of changes in extracellular concentrations of serotonin and noradrenaline in the brain. RESULTS Sharing the workload across institutions, we utilized in vitro techniques with cells and tissues, in vivo receptor binding and microdialysis techniques in rodents, and in vivo PET imaging in non-human primates and humans. Here, we discuss these efforts and review other recently published reports on the use of radioligands to assess changes in endogenous levels of dopamine, serotonin, noradrenaline, γ-aminobutyric acid, glutamate, acetylcholine, and opioid peptides. The emphasis is on assessment of the availability of appropriate translational tools (PET radioligands, pharmacological challenge agents) and on studies in non-human primates and human subjects, as well as current challenges and future directions. CONCLUSIONS PET imaging directed at investigating changes in endogenous neurochemicals, including the work done in NEWMEDS, have highlighted an opportunity to further extend the capability and application of this technology in drug development.
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Affiliation(s)
- Sjoerd J. Finnema
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Mika Scheinin
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland , />Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
| | - Mohammed Shahid
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Jussi Lehto
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
| | - Edilio Borroni
- />Neuroscience Department, Hoffman-La Roche, Basel, Switzerland
| | | | - Jukka Sallinen
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Erik Wong
- />Neuroscience Innovative Medicine Unit, AstraZeneca, Wilmington, DE USA
| | - Lars Farde
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden , />Translational Science Center at Karolinska Institutet, AstraZeneca, Stockholm, Sweden
| | - Christer Halldin
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Sarah Grimwood
- Neuroscience Research Unit, Pfizer Inc, Cambridge, MA, USA. .,, 610 Main Street, Cambridge, MA, 02139, USA.
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Comparison of simultaneous measurement of mouse locomotor activity by radiotelemetry and photobeam methods. J Pharmacol Toxicol Methods 2014; 71:90-4. [PMID: 25219537 DOI: 10.1016/j.vascn.2014.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/05/2014] [Accepted: 09/05/2014] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Locomotor activity recordings are widely used in different physiological and pharmacological studies. There are two mainly used methods - radiotelemetry and photobeam recording systems. To our knowledge, these methods have not previously been directly and simultaneously compared. METHODS The current study consisted of a comparison of locomotor activity data gained simultaneously from radiotelemetry and photobeam recordings, firstly from a robotic device and secondly from an animal experiment performed with mice. RESULTS Data gained from the animal study showed relatively high variation, but overall agreement between the methods was good. DISCUSSION The two methods were cross-validated in the current study. The data gained from both methods were in good general agreement. However, in an animal experiment, e.g. when sedative drugs or other behavior-modifying interventions are used, one should interpret the results with caution as alterations in animal behavior (e.g. in grooming) may possibly not be picked up similarly by the two methods.
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Ostock CY, Lindenbach D, Goldenberg AA, Kampton E, Bishop C. Effects of noradrenergic denervation by anti-DBH-saporin on behavioral responsivity to L-DOPA in the hemi-parkinsonian rat. Behav Brain Res 2014; 270:75-85. [PMID: 24837745 DOI: 10.1016/j.bbr.2014.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/30/2014] [Accepted: 05/05/2014] [Indexed: 11/19/2022]
Abstract
Dopamine (DA) replacement with l-DOPA remains the most effective pharmacotherapy for motor symptoms of Parkinson's disease (PD) including tremor, postural instability, akinesia, and bradykinesia. Prolonged L-DOPA use frequently leads to deleterious side effects including involuntary choreic and dystonic movements known as L-DOPA induced dyskinesias (LID). DA loss in PD is frequently accompanied by concomitant noradrenergic (NE) denervation of the locus coeruleus (LC); however, the effects of NE loss on L-DOPA efficacy and LID remain controversial and are often overlooked in traditional animal models of PD. The current investigation examined the role of NE loss in L-DOPA therapy by employing the NE specific neurotoxin anti-DA-beta hydroxylase saporin (αDBH) in a rat model of PD. Rats received unilateral 6-hydroxydopamine lesions of the medial forebrain bundle to deplete nigral DA and intraventricular injection of vehicle (DA lesioned rats) or αDBH (DANE lesioned rats) to destroy NE neurons bilaterally. Results indicated that αDBH infusion drastically reduced NE neuron markers within the LC compared to rats that received vehicle treatment. Behaviorally, this loss did not alter the development or expression of L-DOPA- or DA agonist-induced dyskinesia. However, rats with additional NE lesions were less responsive to L-DOPA's pro-motor effects. Indeed, DANE lesioned animals rotated less and showed less attenuation of parkinsonian stepping deficits following high doses of L-DOPA than DA lesioned animals. These findings suggest that severe NE loss may reduce L-DOPA treatment efficacy and demonstrate that degradation of the NE system is an important consideration when evaluating L-DOPA effects in later stage PD.
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Affiliation(s)
- Corinne Y Ostock
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
| | - David Lindenbach
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
| | - Adam A Goldenberg
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
| | - Elias Kampton
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
| | - Christopher Bishop
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
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Schmidt KT, Weinshenker D. Adrenaline rush: the role of adrenergic receptors in stimulant-induced behaviors. Mol Pharmacol 2014; 85:640-50. [PMID: 24499709 DOI: 10.1124/mol.113.090118] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Psychostimulants, such as cocaine and amphetamines, act primarily through the monoamine neurotransmitters dopamine (DA), norepinephrine, and serotonin. Although stimulant addiction research has largely focused on DA, medication development efforts targeting the dopaminergic system have thus far been unsuccessful, leading to alternative strategies aimed at abating stimulant abuse. Noradrenergic compounds have shown promise in altering the behavioral effects of stimulants in rodents, nonhuman primates, and humans. In this review, we discuss the contribution of each adrenergic receptor (AR) subtype (α1, α2, and β) to five stimulant-induced behaviors relevant to addiction: locomotor activity, conditioned place preference, anxiety, discrimination, and self-administration. AR manipulation has diverse effects on these behaviors; each subtype profoundly influences outcomes in some paradigms but is inconsequential in others. The functional neuroanatomy and intracellular signaling mechanisms underlying the impact of AR activation/blockade on these behaviors remain largely unknown, presenting a new frontier for research on psychostimulant-AR interactions.
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Affiliation(s)
- Karl T Schmidt
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia
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Li X, Johnson MS, Smith DL, Li Y, Kesterson RA, Allison DB, Nagy TR. Effects of risperidone on energy balance in female C57BL/6J mice. Obesity (Silver Spring) 2013; 21:1850-7. [PMID: 23408466 PMCID: PMC3657586 DOI: 10.1002/oby.20350] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 12/12/2012] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To investigate the effect of risperidone on energy expenditure and weight gain in female C57BL/6J mice. DESIGN AND METHODS Body weight and composition, food intake, energy expenditure, and activity were determined weekly. mRNA expression of uncoupling protein 1 in brown adipose tissue, orexin, and brain-derived neurotrophic factor in the hypothalamus were quantified using real-time PCR. RESULTS Risperidone tended to induce a greater body weight gain (P = 0.052) and significantly higher food intake (P = 0.038) relative to the placebo-treated group. Risperidone-treated mice had a higher resting energy expenditure (P = 0.001) and total energy expenditure (TEE) (P = 0.005) than the placebo group. There were no effects of treatment, time, and treatment by time on non-resting (or activity-related) energy expenditure between groups. Risperidone-treated mice showed a significantly lesser locomotor activity than placebo-treated mice over 3 weeks (P < 0.001). Risperidone induced a higher UCP1 mRNA (P = 0.003) and a lower orexin mRNA (P = 0.001) than placebo. CONCLUSION Risperidone-induced weight gain is associated with hyperphagia and a reduction in locomotor activity in C57BL/6J mice. Additionally, higher total and resting energy expenditure were accompanied by higher levels of UCP1 mRNA in BAT. The increased TEE could not offset the total intake of energy through risperidone-induced hyperphagia, therefore resulting in weight gain in female C57BL/6J mice.
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Affiliation(s)
- Xingsheng Li
- Department of Nutrition Sciences, University of Alabama at Birmingham
| | - Maria S. Johnson
- Department of Nutrition Sciences, University of Alabama at Birmingham
| | - Daniel L. Smith
- Department of Nutrition Sciences, University of Alabama at Birmingham
| | - Yan Li
- Department of Nutrition Sciences, University of Alabama at Birmingham
| | | | - David B. Allison
- Department of Nutrition Sciences, University of Alabama at Birmingham
- Department of Biostatistics, University of Alabama at Birmingham
| | - Tim R. Nagy
- Department of Nutrition Sciences, University of Alabama at Birmingham
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Withdrawal symptoms and rebound syndromes associated with switching and discontinuing atypical antipsychotics: theoretical background and practical recommendations. CNS Drugs 2013; 27:545-72. [PMID: 23821039 DOI: 10.1007/s40263-013-0079-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
With the widespread use of atypical or second-generation antipsychotics, switching treatment has become current practice and more complicated, as the pharmacological profiles of these agents differ substantially despite their similarity in being 'atypical'. All share the ability to block dopamine D₂ receptors, and most of them also block serotonin 5-HT2A receptors. Apart from these common features, some atypical antipsychotics are also able to block or stimulate other dopamine or serotonin receptors, as well as histaminergic, muscarinergic or adrenergic receptors. As a result of the varying receptor affinities, in switching or discontinuing compounds several possible pitfalls have to be considered, including the occurrence of withdrawal and rebound syndromes. This article reviews the pharmacological background of functional blockade or stimulation of receptors of interest in regard to atypical antipsychotics and the implicated potential withdrawal and rebound phenomena. A MEDLINE search was carried out to identify information on withdrawal or rebound syndromes occurring after discontinuation of atypical antipsychotics. Using the resulting literature, we first discuss the theoretical background to the functional consequences of atypical antipsychotic-induced blockade or stimulation of neurotransmitter receptors and, secondly, we highlight the clinical consequences of this. We then review the available clinical literature on switching between atypical antipsychotics, with respect to the occurrence of withdrawal or rebound symptoms. Finally, we offer practical recommendations based on the reviewed findings. The systematic evaluation of withdrawal or rebound phenomena using randomized controlled trials is still understudied. Knowledge of pharmacological receptor-binding profiles may help clinicians in choosing adequate switching or discontinuation strategies for each agent. Results from large switching trials indicate that switching atypical antipsychotics can be performed in a safe manner. Treatment-emergent adverse events during or after switching are not always considered to be, at least in part, associated with the pre-switch antipsychotic. Further studies are needed to substantiate the evidence gained so far on different switching strategies. The use of concomitant medication, e.g., benzodiazepines or anticholinergic drugs, may help to minimize symptoms arising from the discontinuation or switching of antipsychotic treatment.
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Sallinen J, Holappa J, Koivisto A, Kuokkanen K, Chapman H, Lehtimäki J, Piepponen P, Mijatovic J, Tanila H, Virtanen R, Sirviö J, Haapalinna A. Pharmacological Characterisation of a Structurally Novel α2C-Adrenoceptor Antagonist ORM-10921 and its Effects in Neuropsychiatric Models. Basic Clin Pharmacol Toxicol 2013; 113:239-49. [DOI: 10.1111/bcpt.12090] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 05/23/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Jukka Sallinen
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Johanna Holappa
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Ari Koivisto
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Katja Kuokkanen
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Hugh Chapman
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Jyrki Lehtimäki
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Petteri Piepponen
- Division of Pharmacology and Toxicology; University of Helsinki; Helsinki; Finland
| | - Jelena Mijatovic
- Division of Pharmacology and Toxicology; University of Helsinki; Helsinki; Finland
| | - Heikki Tanila
- Department of Neurobiology; A. I. Virtanen Institute; University of Eastern Finland and CNServices Ltd; Kuopio; Finland
| | - Raimo Virtanen
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
| | - Jouni Sirviö
- Department of Neurobiology; Sauloner Ltd.; Kuopio; Finland
| | - Antti Haapalinna
- Orion Corporation; Orion Pharma; Research and Development; Turku; Finland
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Gilsbach R, Hein L. Are the pharmacology and physiology of α₂ adrenoceptors determined by α₂-heteroreceptors and autoreceptors respectively? Br J Pharmacol 2012; 165:90-102. [PMID: 21658028 DOI: 10.1111/j.1476-5381.2011.01533.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
α(2)-Adrenoceptors are important mediators of physiological responses to the endogenous catecholamines noradrenaline and adrenaline. In addition, α(2)-adrenoceptors are pharmacological targets for the treatment of hypertension, sympathetic overactivity and glaucoma. α(2)-Adrenoceptors are also targeted to induce sedation and analgesia in anaesthesia and intensive care. α(2)-Adrenoceptors were first described as presynaptic receptors inhibiting the release of various transmitters from neurons in the central and peripheral nervous systems. In addition to these presynaptic neuronal receptors, α(2)-adrenoceptors were also identified in many non-neuronal cell types of the body. Gene-targeting in mice provided a comprehensive assignment of the physiological and pharmacological functions of these receptors to specific α(2A)-, α(2B) - and α(2C)-adrenoceptor subtypes. However, the specific cell types and signalling pathways involved in these subtype-specific α(2)-adrenoceptor functions were largely unexplored until recently. This review summarizes recent findings from transgenic mouse models, which were generated to define the role of α(2)-adrenoceptors in adrenergic neurons, that is, α(2)-autoreceptors, versus α(2)-adrenoceptors in non-adrenergic neurons, termed α(2)-heteroreceptors. α(2)-Autoreceptors are primarily required to limit release of noradrenaline from sympathetic nerves and adrenaline from adrenal chromaffin cells at rest. These receptors are desensitized upon chronic activation as it may for instance occur due to enhanced sympathetic activity during chronic heart failure. In contrast, pharmacological effects of acutely administered α(2)-adrenoceptor agonist drugs essentially require α(2)-heteroreceptors in non-adrenergic neurons, including analgesia, sedation, hypothermia and anaesthetic-sparing as well as bradycardia and hypotension. Thus a clear picture has emerged of the significance of auto- versus heteroreceptors in mediating the physiological functions of α(2)-adrenoceptors and the pharmacological functions of α(2)-adrenoceptor agonist drugs respectively.
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Affiliation(s)
- Ralf Gilsbach
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany.
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Gilsbach R, Albarrán-Juárez J, Hein L. Pre- versus Postsynaptic Signaling by α2-Adrenoceptors. CURRENT TOPICS IN MEMBRANES 2011; 67:139-60. [DOI: 10.1016/b978-0-12-384921-2.00007-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Docherty JR, Green AR. The role of monoamines in the changes in body temperature induced by 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and its derivatives. Br J Pharmacol 2010; 160:1029-44. [PMID: 20590597 DOI: 10.1111/j.1476-5381.2010.00722.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Hyperthermia is probably the most widely known acute adverse event that can follow ingestion of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) by recreational users. The effect of MDMA on body temperature is complex because the drug has actions on all three major monoamine neurotransmitters [5-hydroxytryptamine (5-HT), dopamine and noradrenaline], both by amine release and by direct receptor activation. Hyperthermia and hypothermia can be induced in laboratory animals by MDMA, depending on the ambient temperature, and involve both central thermoregulation and peripheral changes in blood flow and thermogenesis. Acute 5-HT release is not directly responsible for hyperthermia, but 5-HT receptors are involved in modulating the hyperthermic response. Impairing 5-HT function with a neurotoxic dose of MDMA or p-chlorophenylalanine alters the subsequent MDMA-induced hyperthermic response. MDMA also releases dopamine, and evidence suggests that this transmitter is involved in both the hyperthermic and hypothermic effects of MDMA in rats. The noradrenergic system is also involved in the hyperthermic response to MDMA. MDMA activates central alpha(2A)-adrenoceptors and peripheral alpha(1)-adrenoceptors to produce cutaneous vasoconstriction to restrict heat loss, and beta(3)-adrenoceptors in brown adipose tissue to increase heat generation. The hyperthermia occurring in recreational users of MDMA can be fatal, but data reviewed here indicate that it is unlikely that any single pharmaceutical agent will be effective in reversing the hyperthermia, so careful body cooling remains the principal clinical approach. Crucially, educating recreational users about the potential dangers of hyperthermia and the control of ambient temperature should remain key approaches to prevent this potentially fatal problem.
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Affiliation(s)
- J R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Ireland.
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Preclinical characterization of BRL 44408: antidepressant- and analgesic-like activity through selective alpha2A-adrenoceptor antagonism. Int J Neuropsychopharmacol 2010; 13:1193-205. [PMID: 20047711 DOI: 10.1017/s1461145709991088] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Biogenic amines such as norepinephrine, dopamine, and serotonin play a well-described role in the treatment of mood disorders and some types of pain. As alpha2A-adrenoceptors regulate the release of these neurotransmitters, we examined the therapeutic potential of BRL 44408, a potent (Ki=8.5 nM) and selective (>50-fold) alpha2A-adrenoceptor antagonist (K(B)=7.9 nM). In rats, BRL 44408 penetrated the central nervous system resulting in peak brain and plasma concentrations of 586 ng/g and 1124 ng/ml, respectively. In a pharmacodynamic assay, pretreatment with BRL 44408 to rats responding under a fixed-ratio 30 operant response paradigm resulted in a rightward shift of the clonidine dose-response curve, an effect indicative of alpha2-adrenoceptor antagonism in vivo. Consistent with presynaptic autoreceptor antagonism and tonic regulation of neurotransmitter release, acute administration of BRL 44408 elevated extracellular concentrations of norepinephrine and dopamine, but not serotonin, in the medial prefrontal cortex. Additionally, BRL 44408, probably by inhibiting alpha2A heteroceptors, produced a significant increase in cortical levels of acetylcholine. In the forced swim test and schedule-induced polydipsia assay, BRL 44408 produced an antidepressant-like response by dose-dependently decreasing immobility time and adjunctive water intake, respectively, while in a model of visceral pain, BRL 44408 exhibited analgesic activity by decreasing para-phenylquinone (PPQ)-induced abdominal stretching. Finally, BRL 44408 did not produce deficits in overall motor coordination nor alter general locomotor activity. This preclinical characterization of the neurochemical and behavioural profile of BRL 44408 suggests that selective antagonism of alpha2A-adrenoceptors may represent an effective treatment strategy for mood disorders and visceral pain.
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Kawamura K, Akiyama M, Yui J, Yamasaki T, Hatori A, Kumata K, Wakizaka H, Takei M, Nengaki N, Yanamoto K, Fukumura T, Zhang MR. In vivo evaluation of limiting brain penetration of probes for α(2C)-adrenoceptor using small-animal positron emission tomography. ACS Chem Neurosci 2010; 1:520-8. [PMID: 22778842 DOI: 10.1021/cn1000364] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 05/25/2010] [Indexed: 11/30/2022] Open
Abstract
To evaluate in vivo brain penetration of α(2C)-adrenoceptor (α(2C)-AR) antagonists as a therapeutic agent, we synthesized two new (11)C-labeled selective α(2C)-AR antagonists 4-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-2-yl)methyl-2-aryl-7-methoxybenzofuran ([(11)C]MBF) and acridin-9-yl-[4-(4-methylpiperazin-1-yl)phenyl]amine ([(11)C]JP-1302) as α(2C)-AR-selective positron emission tomography (PET) probes. The radiochemical yield, specific activity, and radiochemical purity of these probes was appropriate for injection. To evaluate whether the brain penetration of these probes is related to the function of two major drug efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), we performed PET studies using wild-type and P-gp/Bcrp knockout mice. In wild-type mice, the radioactivity level after injection with [(11)C]MBF initially increased and effluxed immediately from the brain, whereas that with [(11)C]JP-1302 was distributed throughout the brain. However, the regional distribution of radioactivity after injection with [(11)C]JP-1302 in the brain was different from that of α(2C)-ARs. In P-gp/Bcrp knockout mice, uptake of [(11)C]MBF was approximately 3.7-fold higher and that of [(11)C]JP-1302 was approximately 1.6-fold higher than those in wild-type mice. These results indicate that brain penetration of the two PET probes was affected by modulation of P-gp and Bcrp functions.
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Affiliation(s)
| | | | - Joji Yui
- Department of Molecular Probes and
| | | | | | | | - Hidekatsu Wakizaka
- Department of Molecular Probes and
- Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Makoto Takei
- Department of Molecular Probes and
- Tokyo Nuclear Services Co., Ltd., Tokyo 110-0005, Japan
| | - Nobuki Nengaki
- Department of Molecular Probes and
- SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Kazuhiko Yanamoto
- Department of Molecular Probes and
- Division of Health Sciences, Graduate School of Medicine, Osaka University, Suita 565-0871, Japan
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Laarakker MC, Raai JRV, van Lith HA, Ohl F. The role of the alpha 2A-adrenoceptor in mouse stress-coping behaviour. Psychoneuroendocrinology 2010; 35:490-502. [PMID: 19766405 DOI: 10.1016/j.psyneuen.2009.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 08/18/2009] [Accepted: 08/21/2009] [Indexed: 11/30/2022]
Abstract
Acute stress is known to impair memory functions in both men and laboratory rodents. In human the alpha 2A-adrenoceptor system is known to play a critical role in regulating acute neuropsychological stress responses and, ultimately, stress-coping behaviour. In search for neurobiological and central nervous mechanisms behind these behaviours we investigated if the alpha 2A-adrenoceptor is involved in these mechanisms in mice. Phenotypical differences between the A/J and C57BL/6J (B6) mouse inbred strains were evaluated in previous studies. These data showed significant strain differences in various motivational systems (anxiety, exploration, locomotion, memory etc.). From the literature it is known that chromosome 19 contains the gene for the adrenergic alpha 2A receptor that is thought to be involved in emotional behaviours, among others anxiety-related avoidance behaviour and arousal. We investigated if this pathway could possibly be involved in avoidance/arousal susceptibility by applying an agonist (dexmedetomidine) and an antagonist (atipamezole) of the alpha 2A-adrenoceptor to male mice from a consomic strain (C57BL/6J-Chr 19(A)/NaJ, abbreviated to CSS19=anxious), and the corresponding donor (A/J=anxious) and host (B6=non-anxious) strains. The mice were tested in the modified hole board (mHB) test which allows for the assessment of a variety of behavioural patterns by use of only one test. In addition, a forced swimming test (FST) was conducted to test for stress-coping behaviour. Results of the behavioural testing in the mHB-test showed significant strains differences and strain-specific treatment effects for parameters describing anxiety-related endophenotypes. The FST revealed effects of dexmedetomidine and atipamezole on stress-coping behaviour. In conclusion, the involvement of the alpha 2A-adrenoceptor, located on mouse chromosome 19, on anxiety-related behaviour remains unclear and will possibly not play a main role in the development of anxiety-related behaviour in mice. However, we could show involvement of this receptor in stress-coping behaviour in mice.
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Affiliation(s)
- Marijke C Laarakker
- Department of Animals in Science & Society, Division of Laboratory Animal Science, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
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Sato K, Kimura T, Nishikawa T, Tobe Y, Masaki Y. Neuroprotective effects of a combination of dexmedetomidine and hypothermia after incomplete cerebral ischemia in rats. Acta Anaesthesiol Scand 2010; 54:377-82. [PMID: 19860751 DOI: 10.1111/j.1399-6576.2009.02139.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Dexmedetomidine and hypothermia are known to reduce neuronal injury following cerebral ischemia. We examined whether a combination of dexmedetomidine and hypothermia reduces brain injury after transient forebrain ischemia in rats to a greater extent than either treatment alone. METHODS Thirty-eight male Sprague-Dawley rats were anesthetized with fentanyl and nitrous oxide in oxygen. Four groups were tested: group C (saline 1 ml/kg, temporal muscle temperature 37.5 degrees C); group H (saline 1 ml/kg, 35.0 degrees C); group D (dexmedetomidine 100 microg/kg, 37.5 degrees C); and group DH (dexmedetomidine 100 microg/kg, 35.0 degrees C). Dexmedetomidine or saline was administered intraperitoneally 30 min before ischemia. Cerebral ischemia was produced by right carotid artery ligation with hemorrhagic hypotension (mean arterial pressure 40 mmHg) for 20 min. Neurologic outcome was evaluated at 24, 48, and 72 h after ischemia. Histopathology was evaluated in the caudate and hippocampus at 72 h after ischemia. RESULTS Neurologic outcome was significantly better in the group DH than the group C (P<0.05), whereas it was similar between the group DH and the groups D or H. Survival rate of the hippocampal CA1 neurons was significantly greater in groups D, H, and DH than group C (P<0.05). Histopathologic injury in the caudate section was significantly less in groups H and DH than group C (P<0.05). CONCLUSION The combination of dexmedetomidine and hypothermia improved short-term neurologic outcome compared with the control group, whereas the combination therapy provided comparable neuroprotection with either of the two therapies alone.
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Affiliation(s)
- K Sato
- Department of Anesthesia and Intensive Care Medicine, Akita University School of Medicine, Akita 010-8543, Japan
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Gyires K, Zádori ZS, Török T, Mátyus P. α2-Adrenoceptor subtypes-mediated physiological, pharmacological actions. Neurochem Int 2009; 55:447-53. [DOI: 10.1016/j.neuint.2009.05.014] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 05/16/2009] [Accepted: 05/18/2009] [Indexed: 11/29/2022]
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Höcker J, Gruenewald M, Meybohm P, Schaper C, Scholz J, Steinfath M, Bein B. Nefopam but not physostigmine affects the thermoregulatory response in mice via alpha(2)-adrenoceptors. Neuropharmacology 2009; 58:495-500. [PMID: 19744502 DOI: 10.1016/j.neuropharm.2009.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 08/13/2009] [Accepted: 09/01/2009] [Indexed: 11/16/2022]
Abstract
Nefopam, a non-opioid, centrally acting benzoxazocine analgesic, proved to be as efficient in treatment of postanaesthetic thermoregulatory shivering as clonidine or meperidine. However, its exact mechanism of action is still unclear. Potent anti-shivering activity was also demonstrated for physostigmine primarily based on cholinergic but probably also different additional mechanisms of action. Hypothesizing an involvement of alpha(2)-adrenoceptors we studied their role in nefopam- and physostigmine-mediated thermoregulation in a mouse model of nonshivering thermogenesis. To differentiate possible alpha(2)-adrenoceptor subtype-specific interactions, we analysed wildtype mice and mice with deletion of the alpha(2A)-, alpha(2B)- or alpha(2C)-adrenoceptor (knock out). Ten mice of each genotype (n = 40) were administered saline, saline plus atipamezole, 1 mg/kg nefopam, 25 mg/kg nefopam, 25 mg/kg nefopam plus atipamezole, physostigmine and physostigmine plus atipamezole intraperitoneally. Each mouse was randomly subjected to each of the seven different treatments. Afterwards, the mice were positioned into a plexiglas chamber where rectal temperature and mixed expired carbon dioxide were measured during following whole body cooling. Thermoregulatory threshold temperature of nonshivering thermogenesis and maximum response intensity were analysed. Nefopam decreased the thermoregulatory threshold temperature in wildtype, alpha(2B)- and alpha(2C)-adrenoceptor mice. This effect was partially abolished by additional administration of the alpha(2)-adrenoceptor antagonist atipamezole. In alpha(2A)-adrenoceptor knock out mice, nefopam did not affect the thermoregulatory threshold. In contrast, physostigmine decreased the thermoregulatory threshold in wildtype and all alpha(2)-adrenoceptor knock out mice independently from additional atipamezole administration. Our results indicate an important role of the alpha(2A)-adrenoceptor in the thermoregulatory response induced by nefopam but not by physostigmine in mice.
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Affiliation(s)
- Jan Höcker
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Germany.
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Albarrán-Juárez J, Gilsbach R, Piekorz RP, Pexa K, Beetz N, Schneider J, Nürnberg B, Birnbaumer L, Hein L. Modulation of alpha2-adrenoceptor functions by heterotrimeric Galphai protein isoforms. J Pharmacol Exp Ther 2009; 331:35-44. [PMID: 19589951 DOI: 10.1124/jpet.109.157230] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Subtype diversity of heterotrimeric G proteins and G protein-coupled receptors enables a wide spectrum of signal transduction. However, the significance of isoforms within receptor or G protein subfamilies has not been fully elucidated. In the present study, we have tested whether alpha(2)-adrenoceptors require specific Galpha isoforms for their function in vivo. In particular, we analyzed the role of the highly homologous Galpha(i) isoforms, Galpha(i1), Galpha(i2), and Galpha(i3), in typical alpha(2)-adrenoceptor-controlled functions. Mice with targeted deletions in the genes encoding Galpha(i1), Galpha(i2), or Galpha(i3) were used to test the effects of alpha(2)-adrenoceptor stimulation by the agonist medetomidine. The alpha(2)-adrenoceptor agonist medetomidine inhibited [(3)H]norepinephrine release from isolated prefrontal brain cortex or cardiac atria tissue specimens with similar potency and efficacy in tissues from wild-type or Galpha(i)-deficient mice. In vivo, bradycardia, hypotension, induction of sleep, antinociception, and hypothermia induced by alpha(2)-adrenoceptor activation did not differ between wild-type and Galpha(i)-knockout mice. However, the effects of the alpha(2)-agonists medetomidine or 5-bromo-6-(2-imidazolin-2-ylamino)quin-oxaline tartrate (UK14,304) on spontaneous locomotor activity or anesthetic sparing were reduced or absent, respectively, in mice lacking Galpha(i2). In microdissected locus coeruleus neurons or postganglionic sympathetic neurons from stellate ganglia, all three Galpha(i) subunits were expressed as determined by quantitative reverse transcription-polymerase chain reaction, with Galpha(i1) and Galpha(i2) dominating over Galpha(i3). Functional redundancy of the highly homologous Galpha(i) isoforms may predominate over specificity to regulate distinct intracellular pathways downstream of alpha(2)-adrenoceptors in vivo. In contrast, inhibition of locomotor activity and anesthetic sparing may be elicited by a specific coupling of alpha(2A)-adrenoceptors via the Galpha(i2) isoform to intracellular pathways.
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Affiliation(s)
- Julián Albarrán-Juárez
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Germany
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Fairbanks CA, Stone LS, Wilcox GL. Pharmacological profiles of alpha 2 adrenergic receptor agonists identified using genetically altered mice and isobolographic analysis. Pharmacol Ther 2009; 123:224-38. [PMID: 19393691 DOI: 10.1016/j.pharmthera.2009.04.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Accepted: 04/09/2009] [Indexed: 12/24/2022]
Abstract
Endogenous, descending noradrenergic fibers impose analgesic control over spinal afferent circuitry mediating the rostrad transmission of pain signals. These fibers target alpha 2 adrenergic receptors (alpha(2)ARs) on both primary afferent terminals and secondary neurons, and their activation mediates substantial inhibitory control over this transmission, rivaling that of opioid receptors which share a similar pattern of distribution. The terminals of primary afferent nociceptive neurons and secondary spinal dorsal horn neurons express alpha(2A)AR and alpha(2C)AR subtypes, respectively. Spinal delivery of these agents serves to reduce their side effects, which are mediated largely at supraspinal sites, by concentrating the drugs at the spinal level. Targeting these spinal alpha(2)ARs with one of five selective therapeutic agonists, clonidine, dexmedetomidine, brimonidine, ST91 and moxonidine, produces significant antinociception that can work in concert with opioid agonists to yield synergistic antinociception. Application of several genetically altered mouse lines had facilitated identification of the primary receptor subtypes that likely mediate the antinociceptive effects of these agents. This review provides first an anatomical description of the localization of the three subtypes in the central nervous system, second a detailed account of the pharmacological history of each of the six primary agonists, and finally a comprehensive report of the specific interactions of other GPCR agonists with each of the six principal alpha(2)AR agonists featured.
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Affiliation(s)
- Carolyn A Fairbanks
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA
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Fagerholm V, Rokka J, Nyman L, Sallinen J, Tiihonen J, Tupala E, Haaparanta M, Hietala J. Autoradiographic characterization of α2C-adrenoceptors in the human striatum. Synapse 2008; 62:508-15. [DOI: 10.1002/syn.20520] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Karkoulias G, Mastrogianni O, Papathanasopoulos P, Paris H, Flordellis C. α2-Adrenergic receptors activate cyclic AMP-response element-binding protein through arachidonic acid metabolism and protein kinase A in a subtype-specific manner. J Neurochem 2007; 103:882-95. [PMID: 17680988 DOI: 10.1111/j.1471-4159.2007.04852.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
On incubation with epinephrine, PC12 cells stably expressing alpha2-adrenergic receptor (alpha2-AR) undergo morphological and biochemical changes characteristic of neuron-like differentiation. The present study shows that alpha2-AR stimulation increases the phosphorylation of the transcription factor cAMP-response element-binding protein (CREB), the activity of a CRE-reporter plasmid and the expression of cyclin D1 with subtype-dependent efficiency (alpha2A approximately alpha2C >> alpha2B). The effects of epinephrine were mimicked by cell exposure to forskolin or to exogenous arachidonic acid (AA) and they were abrogated by prior treatment with the inhibitor of phospholipase C (PLC) (U73122) or the inhibitor of cytochrome P450-dependent epoxygenase, ketoconazole. On the other hand, treatment of the cells with epinephrine caused activation of protein kinase A (PKA), which was fully abolished by ketoconazole. Inhibition of PKA activity with H89 or ketoconazole abolished the effects of epinephrine on CREB, suggesting that activation of the cAMP/PKA pathway by AA epoxy-derivatives is responsible for CREB activation by alpha2-ARs. The effects of epinephrine were unaffected by LY294002. Furthermore, treatment with staurosporine, tyrphostin AG1478, PP1 or PD98059 did not change the extent of CREB phosphorylation but enhanced its transcriptional activity. Altogether, our results demonstrate that, in PC12 cells, the alpha2-AR subtypes cause phosphorylation and activation of CREB through a pathway involving stimulation of PLC, AA release, generation of epoxygenase derivative and increase of PKA activity. They also suggest attenuation of CREB transcriptional activity by mitogen-activated protein kinase, protein kinase C and Src kinases.
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Affiliation(s)
- Georgios Karkoulias
- Department of Pharmacology, School of Medicine, University of Patras, Rio Patras, Greece
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Linden AM, Sandu C, Aller MI, Vekovischeva OY, Rosenberg PH, Wisden W, Korpi ER. TASK-3 knockout mice exhibit exaggerated nocturnal activity, impairments in cognitive functions, and reduced sensitivity to inhalation anesthetics. J Pharmacol Exp Ther 2007; 323:924-34. [PMID: 17875609 DOI: 10.1124/jpet.107.129544] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The TASK-3 channel is an acid-sensitive two-pore-domain K+ channel, widely expressed in the brain and probably involved in regulating numerous neuronal populations. Here, we characterized the behavioral and pharmacological phenotypes of TASK-3 knockout (KO) mice. Circadian locomotor activity measurements revealed that the nocturnal activity of the TASK-3 KO mice was increased by 38% (P < 0.01) compared with wild-type littermate controls, light phase activity being similar. Although TASK-3 channels are abundant in cerebellar granule cells, the KO mice performed as well as the wild-type mice in walking on a rotating rod or along a 1.2-cm-diameter beam. However, they fell more frequently from a narrower 0.8-cm beam. The KO mice showed impaired working memory in the spontaneous alternation task, with the alternation percentage being 62 +/- 3% for the wild-type mice and 48 +/- 4% (P < 0.05) for the KO mice. Likewise, during training for the Morris water-maze spatial memory task, the KO mice were slower to find the hidden platform, and in the probe trial, the female KO mice visited fewer times the platform quadrant than the male KO and wild-type mice. In pharmacological tests, the TASK-3 KO mice showed reduced sensitivity to the inhalation anesthetic halothane and the cannabinoid receptor agonist WIN55212-2 mesylate [(R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone mesylate] but unaltered responses to the alpha2 adrenoceptor agonist dexmedetomidine, the i.v. anesthetic propofol, the opioid receptor agonist morphine, and the local anesthetic lidocaine. Overall, our results suggest important contributions of TASK-3 channels in the neuronal circuits regulating circadian rhythms, cognitive functions, and mediating specific pharmacological effects.
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Affiliation(s)
- Anni-Maija Linden
- Institute of Biomedicine, Pharmacology, University of Helsinki, POB 63 (Haartmaninkatu 8), 00014 University of Helsinki, Finland.
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Karkoulias G, Mastrogianni O, Ilias I, Lymperopoulos A, Taraviras S, Tsopanoglou N, Sitaras N, Flordellis CS. Alpha 2-adrenergic receptors decrease DNA replication and cell proliferation and induce neurite outgrowth in transfected rat pheochromocytoma cells. Ann N Y Acad Sci 2007; 1088:335-45. [PMID: 17192578 DOI: 10.1196/annals.1366.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alpha 2-adrenergic receptors (alpha(2)-ARs) have a widespread distribution in the central nervous system (CNS) and affect a number of biochemical and behavioral functions, including stimulation of prefrontal cortex (PFC) and cognitive function. In addition to its role as a classical neurotransmitter, norepinephrine (NE) has been recently shown to exert an important influence on the plasticity in areas of the brain where neurogenesis persists in the adult, notably the subgranular zone (SGZ) within the dentate gyrus of the hippocampus and the olfactory bulb (OB). In regulating adult neurogenesis, the noradrenergic system is functionally integrated with chronic stress and depression. Chronic stress, depression, or depletion of NE in vivo suppress, and antidepressant treatments induce hippocampal neurogenesis by down- or upregulating, respectively, cell proliferation. In the present study we show that alpha(2)-AR subtypes promote the differentiation rather than cell proliferation of PC12 cells. It is conceivable that alpha(2)-ARs might contribute neurotrophic actions in vivo synergistically or in permutation with other neurotrophic factors.
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Affiliation(s)
- G Karkoulias
- Department of Pharmacology, School of Medicine, University of Patras-Rion, GR-26504, Greece
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Rommelfanger KS, Weinshenker D. Norepinephrine: The redheaded stepchild of Parkinson's disease. Biochem Pharmacol 2007; 74:177-90. [PMID: 17416354 DOI: 10.1016/j.bcp.2007.01.036] [Citation(s) in RCA: 184] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 01/27/2007] [Accepted: 01/29/2007] [Indexed: 01/12/2023]
Abstract
Parkinson's disease (PD) affects approximately 1% of the world's aging population. Despite its prevalence and rigorous research in both humans and animal models, the etiology remains unknown. PD is most often characterized by the degeneration of dopamine (DA) neurons in the substantia nigra pars compacta (SNc), and models of PD generally attempt to mimic this deficit. However, PD is a true multisystem disorder marked by a profound but less appreciated loss of cells in the locus coeruleus (LC), which contains the major group of noradrenergic neurons in the brain. Historic and more recent experiments exploring the role of norepinephrine (NE) in PD will be analyzed in this review. First, we examine the evidence that NE is neuroprotective and that LC degeneration sensitizes DA neurons to damage. The second part of this review focuses on the potential contribution of NE loss to the behavioral symptoms associated with PD. We propose that LC loss represents a crucial turning point in PD progression and that pharmacotherapies aimed at restoring NE have important therapeutic potential.
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Affiliation(s)
- K S Rommelfanger
- Department of Human Genetics, Emory University, Atlanta, GA 30322, United States
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Sallinen J, Höglund I, Engström M, Lehtimäki J, Virtanen R, Sirviö J, Wurster S, Savola JM, Haapalinna A. Pharmacological characterization and CNS effects of a novel highly selective alpha2C-adrenoceptor antagonist JP-1302. Br J Pharmacol 2007; 150:391-402. [PMID: 17220913 PMCID: PMC2189732 DOI: 10.1038/sj.bjp.0707005] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Pharmacological validation of novel functions for the alpha2A-, alpha2B-, and alpha2C-adrenoceptor (AR) subtypes has been hampered by the limited specificity and subtype-selectivity of available ligands. The current study describes a novel highly selective alpha2C-adrenoceptor antagonist, JP-1302 (acridin-9-yl-[4-(4-methylpiperazin-1-yl)-phenyl]amine). EXPERIMENTAL APPROACH Standard in vitro binding and antagonism assays were employed to demonstrate the alpha2C-AR specificity of JP-1302. In addition, JP-1302 was tested in the forced swimming test (FST) and the prepulse-inhibition of startle reflex (PPI) model because mice with genetically altered alpha2C-adrenoceptors have previously been shown to exhibit different reactivity in these tests when compared to wild-type controls. KEY RESULTS JP-1302 displayed antagonism potencies (KB values) of 1,500, 2,200 and 16 nM at the human alpha2A-, alpha2B-, and alpha2C-adrenoceptor subtypes, respectively. JP-1302 produced antidepressant and antipsychotic-like effects, i.e. it effectively reduced immobility in the FST and reversed the phencyclidine-induced PPI deficit. Unlike the alpha2-subtype non-selective antagonist atipamezole, JP-1302 was not able to antagonize alpha2-agonist-induced sedation (measured as inhibition of spontaneous locomotor activity), hypothermia, alpha2-agonist-induced mydriasis or inhibition of vas deferens contractions, effects that have been generally attributed to the alpha2A-adrenoceptor subtype. In contrast to JP-1302, atipamezole did not antagonize the PCP-induced prepulse-inhibition deficit. CONCLUSIONS AND IMPLICATIONS The results provide further support for the hypothesis that specific antagonism of the alpha2C-adrenoceptor may have therapeutic potential as a novel mechanism for the treatment of neuropsychiatric disorders.
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Affiliation(s)
- J Sallinen
- Orion Corporation ORION PHARMA, Research and Development, Turku, Finland.
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41
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Karkoulias G, Flordellis C. Delayed transactivation of the receptor for nerve growth factor is required for sustained signaling and differentiation by alpha2-adrenergic receptors in transfected PC12 cells. Cell Signal 2006; 19:945-57. [PMID: 17215105 DOI: 10.1016/j.cellsig.2006.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 11/06/2006] [Accepted: 11/06/2006] [Indexed: 11/26/2022]
Abstract
Alpha2-adrenergic receptors have been reported to induce subtype-specific neuronal differentiation in vitro, but the signaling mechanisms that mediate this effect have not been characterized. In the present study we found that stimulated alpha2-ARs induce delayed transactivation of TrkA in PC12 cells. The transactivation of TrkA was sensitive to the PP1 inhibitor of the Src family kinases and required prior transactivation of the EGF receptor. Moreover, alpha2-adrenergic receptors induced sustained activation of MAPK and Akt. The sustained activation of Akt, but not of MAPK, was subtype-specific and correlated with the neuronal differentiation of PC12 cells, with the order alpha2A<alpha2B<alpha2C. Furthermore, stimulated alpha2-ARs induced an increased over time expression of the cell cycle associated proteins, p21WAF1 and Cyclin D1 and led to cell cycle arrest in a similar subtype-specific manner. Contrary to sustained activation of MAPK, the persistent activation of Akt and of p21WAF1 and Cyclin D1 as well as neurite outgrowth and expression of the neuronal marker peripherin, were all blocked by K252a an inhibitor of TrkA activity. Together these results demonstrate a novel outcome following alpha2-AR-mediated EGFR transactivation, being the consecutive transactivation of TrkA, and that this event may mediate the subtype-specific differentiation of alpha2-AR-expressing PC12 cells.
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Affiliation(s)
- Georgios Karkoulias
- Department of Pharmacology, School of Medicine, University of Patras, 26110 Rio Patras, Greece
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42
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Sierralta W, Hernández A, Valladares L, Pérez H, Mondaca M, Soto-Moyano R. Mild prenatal protein malnutrition increases α2C-adrenoceptor expression in the rat cerebral cortex during postnatal life. Brain Res Bull 2006; 69:580-6. [PMID: 16647586 DOI: 10.1016/j.brainresbull.2006.02.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 02/27/2006] [Indexed: 10/24/2022]
Abstract
Mild reduction in the protein content in the diet of pregnant rats from 25 to 8% casein, calorically compensated by carbohydrates, does not alter body and brain weights of rat pups at birth, but results in significant changes of the concentration and release of cortical noradrenaline during postnatal life, together with impaired long-term potentiation and memory formation. Since some central noradrenergic receptors are critically involved in neuroplasticity, the present study evaluated, by utilizing immunohistochemical methods, the effect of mild prenatal protein malnutrition on the alpha 2C-adrenoceptor expression in the frontal and occipital cortices of 8- and 60-day-old rats. At day 8 of postnatal age, prenatally malnourished rats exhibited a three-fold increase of alpha 2C-adrenoceptor expression in both the frontal and the occipital cortices, as compared to well-nourished controls. At 60 days of age, prenatally malnourished rats showed normal expression levels scores of alpha 2C-adrenoceptor in the neocortex. Results suggest that overexpression of neocortical alpha 2C-adrenoceptors during early postnatal life, subsequent to mild prenatal protein malnutrition, could in part be responsible for neural and behavioral disturbances showing prenatally malnourished animals during the postnatal life.
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Affiliation(s)
- Walter Sierralta
- Institute of Nutrition and Food Technology (INTA), University of Chile, Santiago, Chile
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43
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Szot P, White SS, Greenup JL, Leverenz JB, Peskind ER, Raskind MA. Compensatory changes in the noradrenergic nervous system in the locus ceruleus and hippocampus of postmortem subjects with Alzheimer's disease and dementia with Lewy bodies. J Neurosci 2006; 26:467-78. [PMID: 16407544 PMCID: PMC6674412 DOI: 10.1523/jneurosci.4265-05.2006] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In Alzheimer's disease (AD), there is a significant loss of locus ceruleus (LC) noradrenergic neurons. However, functional and anatomical evidence indicates that the remaining noradrenergic neurons may be compensating for the loss. Because the noradrenergic system plays an important role in learning and memory, it is important to determine whether compensation occurs in noradrenergic neurons in the LC and hippocampus of subjects with AD or a related dementing disorder, dementia with Lewy bodies (DLB). We observed profound neuronal loss in the LC in AD and DLB subjects with three major changes in the noradrenergic system consistent with compensation: (1) an increase in tyrosine hydroxylase (TH) mRNA expression in the remaining neurons; (2) sprouting of dendrites into peri-LC dendritic zone, as determined by alpha2-adrenoreceptors (ARs) and norepinephrine transporter binding sites; and (3) sprouting of axonal projections to the hippocampus as determined by alpha2-ARs. In AD and DLB subjects, the postsynaptic alpha1-ARs were normal to elevated. Expression of alpha1A- and alpha2A-AR mRNA in the hippocampus of AD and DLB subjects were not altered, but expression of alpha1D- and alpha2C-AR mRNA was significantly reduced in the hippocampus of AD and DLB subjects. Therefore, in AD and DLB subjects, there is compensation occurring in the remaining noradrenergic neurons, but there does appear to be a loss of specific AR in the hippocampus. Because changes in these noradrenergic markers in AD versus DLB subjects were similar (except neuronal loss and the increase in TH mRNA were somewhat greater in DLB subjects), the presence of Lewy bodies in addition to plaques and tangles in DLB subjects does not appear to further affect the noradrenergic compensatory changes.
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MESH Headings
- Adrenergic alpha-Antagonists/metabolism
- Adult
- Aged
- Aged, 80 and over
- Alzheimer Disease/metabolism
- Alzheimer Disease/pathology
- Dendrites/ultrastructure
- Female
- Fluoxetine/analogs & derivatives
- Fluoxetine/metabolism
- Hippocampus/chemistry
- Hippocampus/pathology
- Humans
- Idazoxan/analogs & derivatives
- Idazoxan/metabolism
- In Situ Hybridization
- Lewy Body Disease/metabolism
- Lewy Body Disease/pathology
- Locus Coeruleus/chemistry
- Locus Coeruleus/pathology
- Male
- Middle Aged
- Nerve Tissue Proteins/analysis
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Norepinephrine/chemistry
- Norepinephrine/physiology
- Norepinephrine Plasma Membrane Transport Proteins/analysis
- Norepinephrine Plasma Membrane Transport Proteins/metabolism
- Prazosin/metabolism
- RNA, Messenger/analysis
- RNA, Messenger/biosynthesis
- Receptors, Adrenergic, alpha-1/analysis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/analysis
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Tetralones/metabolism
- Tyrosine 3-Monooxygenase/analysis
- Tyrosine 3-Monooxygenase/biosynthesis
- Tyrosine 3-Monooxygenase/genetics
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Affiliation(s)
- Patricia Szot
- Northwest Network for Mental Illness Research, Education, and Clinical Center, Veterans Administration Puget Sound Health Care System, Seattle, Washington 98108, USA.
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Paris A, Mantz J, Tonner PH, Hein L, Brede M, Gressens P. The Effects of Dexmedetomidine on Perinatal Excitotoxic Brain Injury are Mediated by the ??2A-Adrenoceptor Subtype. Anesth Analg 2006; 102:456-61. [PMID: 16428542 DOI: 10.1213/01.ane.0000194301.79118.e9] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We performed the current study in mice lacking individual alpha2-adrenoceptor subtypes to elucidate the contribution of alpha(2)-adrenoceptor subtypes to the neuroprotective properties of dexmedetomidine in a model of perinatal excitotoxic brain injury. On postnatal Day 5, wild-type mice and mice lacking alpha2A-adrenoceptor (alpha2A-KO) or alpha2C-adrenoceptor subtypes (alpha2C-KO) were randomly assigned to receive dexmedetomidine (3 microg/kg) or phosphate-buffered saline intraperitoneally. Thirty minutes after the intraperitoneal injection, the glutamatergic agonist ibotenate (10 microg) was intracerebrally injected, producing transcortical necrosis and white matter lesions that mimic perinatal human hypoxic-like lesions. Quantification of the lesions was performed on postnatal Day 10 by histopathologic examination. Dexmedetomidine reduced mean lesion size in the cortex of wild-type mice and alpha2C-KO mice by 44% and 49%, respectively. Ibotenate-induced white matter lesions were reduced by 71% (wild-type mice) and 75% (alpha2C-KO mice) after pretreatment with dexmedetomidine. In contrast, in alpha2A-KO mice, dexmedetomidine did not protect against the cortical excitotoxic insult, and white matter lesions were even more pronounced (82% increase of mean lesion size). Dexmedetomidine provides potent neuroprotection in a model of perinatal excitotoxic brain damage. This effect was completely abolished in alpha2A-KO mice, suggesting that the neuroprotective effect is mediated via the alpha2A-adrenoceptor subtype.
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Affiliation(s)
- Andrea Paris
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Germany.
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45
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Gilsbach R, Faron-Górecka A, Rogóz Z, Brüss M, Caron MG, Dziedzicka-Wasylewska M, Bönisch H. Norepinephrine transporter knockout-induced up-regulation of brain alpha2A/C-adrenergic receptors. J Neurochem 2006; 96:1111-20. [PMID: 16417582 DOI: 10.1111/j.1471-4159.2005.03598.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The norepinephrine transporter (NET) is responsible for the rapid removal of norepinephrine released from sympathetic neurons; this release is controlled by inhibitory alpha(2)-adrenergic receptors (alpha(2)ARs). Long-term inhibition of the NET by antidepressants has been reported to change the density and function of pre- and postsynaptic ARs, which may contribute to the antidepressant effects of NET inhibitors such as desipramine. NET-deficient (NET-KO) mice have been described to behave like antidepressant-treated mice. By means of quantitative real-time PCR we show that mRNAs encoding the alpha(2A)-adrenergic receptor (alpha(2A)AR) and the alpha(2C)-adrenergic receptor (alpha(2C)AR) are up-regulated in the brainstem, and that alpha(2C)AR mRNA is also elevated in the hippocampus and striatum of NET-KO mice. These results were confirmed at the protein level by quantitative autoradiography. The NET-KO mice showed enhanced binding of the selective alpha(2)AR antagonist [(3)H]RX821002 in several brain regions. Most robust increases (20-25%) in alpha(2)AR expression were observed in the hippocampus and in the striatum. Significant increases (16%) were also seen in the extended amygdala and thalamic structures. In an 'in vivo' test, the alpha(2)AR agonist clonidine (0.1 mg/kg) caused a significantly greater reduction of locomotor activity in NET-KO mice than in wild-type mice, showing the relevance of our findings at the functional level.
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Affiliation(s)
- R Gilsbach
- Institute of Pharmacology & Toxicology, University of Bonn, Germany
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46
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Abstract
Cardiovascular regulation by the sympathetic nervous system is mediated by activation of one or more of the nine known subtypes of the adrenergic receptor family; alpha(1A)-, alpha(1B)-, alpha(1D)-, alpha(2A)-, alpha(2B)-, alpha(2C)-, beta(1)-, beta(2)- and beta(3)-ARs (adrenoceptors). The role of the alpha(2)-AR family has long been known to include presynaptic inhibition of neurotransmitter release, diminished sympathetic efferent traffic, vasodilation and vasoconstriction. This complex response is mediated by one of three subtypes which all uniquely affect blood pressure and blood flow. All three subtypes are present in the brain, kidney, heart and vasculature. However, each differentially influences blood pressure and sympathetic transmission. Activation of alpha(2A)-ARs in cardiovascular control centres of the brain lowers blood pressure and decreases plasma noradrenaline (norepinephrine), activation of peripheral alpha(2B)-ARs causes sodium retention and vasoconstriction, whereas activation of peripheral alpha(2C)-ARs causes cold-induced vasoconstriction. In addition, non-selective agonists elicit endothelium-dependent vasodilation and presynaptic inhibition of noradrenaline release. The evidence that each of these receptor subtypes uniquely participates in cardiovascular control is discussed in this review.
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Affiliation(s)
- Nancy L Kanagy
- Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131-5321, USA.
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47
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Manolis AS, Patsouras N, Ilias I, Constantakopoulos J, Pyriohou A, Lymperopoulos A, Spathas DH, Flordellis CS. Lack of association between α2B-adrenergic receptor polymorphism and risk of restenosis following coronary angioplasty and stent implantation – preliminary report. Clin Chem Lab Med 2006; 44:807-12. [PMID: 16776624 DOI: 10.1515/cclm.2006.155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractClin Chem Lab Med 2006;44:807–12.
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Affiliation(s)
- Antonis S Manolis
- First Department of Cardiology, Evagelismos General Hospital of Athens, Athens, Greece
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48
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Bexis S, Docherty JR. Role of alpha2A-adrenoceptors in the effects of MDMA on body temperature in the mouse. Br J Pharmacol 2005; 146:1-6. [PMID: 16025144 PMCID: PMC1576257 DOI: 10.1038/sj.bjp.0706320] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
3,4-Methylenedioxymetamphetamine (MDMA) produces complex effects on body temperature, including hypo- and hyperthermic components that vary with ambient temperature and strain of rat. We have previously reported that MDMA is an alpha(2)-adrenoceptor agonist, and alpha(2)-adrenoceptor agonists such as clonidine produce hypothermia. The purpose of this study was to investigate the effects of MDMA on core body temperature measured by radiotelemetry in conscious wild-type (WT) and alpha(2A)-knockout (alpha(2A)-KO) mice. Clonidine (0.1 mg kg(-1), subcutaneously (s.c.)) produced a hypothermic response in WT mice, but did not significantly affect temperature in alpha(2)-KO mice. MDMA (20 mg kg(-1), s.c.) produced a significant hyperthermia in WT mice beginning at approximately 100 min after injection, recovering by 300 min, but produced a biphasic response, hypothermia followed by hyperthermia, in alpha(2)-KO mice. In WT mice, following the alpha(2A)-adrenoceptor antagonist 2-((4,5-dihydro-1H-imidazol-2-yl)methyl)-2,3-dihydro-1-methyl-1H-isoindole (1 mg kg(-1), s.c.), MDMA (20 mg kg(-1)) produced an initial hypothermia. Hence, alpha(2)-adrenoceptor agonist actions of MDMA contribute to its effects on body temperature, but in a surprising way. Although selective alpha(2A)-adrenoceptor agonism produces hypothermia, the alpha(2A)-adrenoceptor actions of MDMA alter the body temperature response to MDMA from biphasic (hypothermia followed by hyperthermia) to monophasic hyperthemia.
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Affiliation(s)
- Sotiria Bexis
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2
| | - James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2
- Author for correspondence:
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49
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Abstract
PURPOSE OF REVIEW The development of dexmedetomidine, a potent and highly selective alpha2-adrenoceptor agonist, has created new interest in the use of alpha2-adrenoceptor agonists, and has led to its evaluation in various yet non-approved perioperative settings. The current review focuses on the usefulness of dexmedetomidine in anaesthesia practice. RECENT FINDINGS Recently acquired knowledge and experience with dexmedetomidine in perioperative use will be presented and discussed in the context of known pharmacological properties. SUMMARY Dexmedetomidine offers beneficial pharmacological properties, providing dose-dependent sedation, analgesia, sympatholysis and anxiolysis without relevant respiratory depression. The side-effects are predictable from the pharmacological profile of (2-adrenoceptor agonists. In particular, the unique sedative properties of dexmedetomidine resulted in several interesting applications in anaesthesia practice, promising benefits in the perioperative use of this compound. However, dexmedetomidine was approved for sedation in the intensive care unit in the USA in 1999, and administration in anaesthesia practice remains an 'off-label' use. Further studies are needed to establish the role of dexmedetomidine in the perioperative period.
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Affiliation(s)
- Andrea Paris
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, D-24105 Kiel, Germany.
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50
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Juhila J, Honkanen A, Sallinen J, Haapalinna A, Korpi ER, Scheinin M. α2A-Adrenoceptors regulate d-amphetamine-induced hyperactivity and behavioural sensitization in mice. Eur J Pharmacol 2005; 517:74-83. [PMID: 15978573 DOI: 10.1016/j.ejphar.2005.05.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Accepted: 05/10/2005] [Indexed: 11/30/2022]
Abstract
Stimulants, such as d-amphetamine, enhance the release of dopamine in the central nervous system (CNS) and induce locomotor activation in mice. When amphetamine is administered repeatedly, the locomotor activation is progressively increased. This behavioural sensitization may be associated with the development of drug craving, addiction and dependence. Also noradrenergic mechanisms participate in the mediation of the effects of psychostimulants. In this study we show that mice lacking the alpha(2)-adrenoceptor subtype A (alpha(2A)-AR knock-out (KO) on C57Bl/6J background) are supersensitive to the acute locomotor effects of d-amphetamine (5 mg/kg) in a novel environment compared to wild-type (WT) control mice. When both genotypes were treated repeatedly with d-amphetamine (2 mg/kg) they developed locomotor hyperactivation (sensitization), but its amplitude was lower in alpha(2A)-AR KO mice. Development of hyperactivation was reduced in both genotypes by pretreatment with the selective alpha(2)-adrenoceptor antagonist, atipamezole (1 mg/kg). Acute atipamezole also attenuated the expression of d-amphetamine-induced behavioural sensitization especially in WT mice. Interestingly, alpha(2A)-AR KO mice failed to exhibit persistent sensitization after 2 weeks of abstinence from repeated d-amphetamine. Rewarding properties of d-amphetamine, measured by conditioned place preference, were similar in both genotypes. These findings indicate that d-amphetamine-induced acute and sensitized locomotor effects are controlled by alpha(2)-adrenoceptors. Drugs antagonizing the alpha(2A)-adrenoceptor subtype may provide a novel approach for reducing drug sensitization and motor complications caused by dopaminergic agents.
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Affiliation(s)
- Juuso Juhila
- Department of Pharmacology and Clinical Pharmacology, University of Turku, FI-20520 Turku, Finland.
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