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Frau R, Pardu A, Godar S, Bini V, Bortolato M. Combined Antagonism of 5-HT2 and NMDA Receptors Reduces the Aggression of Monoamine Oxidase a Knockout Mice. Pharmaceuticals (Basel) 2022; 15:ph15020213. [PMID: 35215325 PMCID: PMC8875523 DOI: 10.3390/ph15020213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 02/04/2023] Open
Abstract
The enzyme monoamine oxidase A (MAOA) catalyzes the degradation of several neurotransmitters, including serotonin. A large body of evidence has shown that genetic MAOA deficiency predisposes humans and mice to aggression and antisocial behavior. We previously documented that the aggression of male MAOA-deficient mice is contributed by serotonin 5-HT2 and glutamate N-methyl-D-aspartate (NMDA) receptors in the prefrontal cortex (PFC). Indeed, blocking either receptor reduces the aggression of MAOA knockout (KO) mice; however, 5-HT2 receptor antagonists, such as ketanserin (KET), reduce locomotor activity, while NMDA receptor blockers are typically associated with psychotomimetic properties. To verify whether NMDA receptor blockers induce psychotomimetic effects in MAOA KO mice, here we tested the effects of these compounds on prepulse inhibition (PPI) of the acoustic startle reflex. We found that male MAOA KO mice are hypersensitive to the PPI-disrupting properties of NMDA receptor antagonists, including the non-competitive antagonist dizocilpine (DIZ; 0.1, 0.3 mg/kg, IP) and the NR2B subunit-specific blocker Ro-256981 (5, 10 mg/kg, IP). Since KET has been previously shown to counter the PPI deficits caused by NMDA receptor antagonists, we tested the behavioral effects of the combination of KET (2 mg/kg, IP) and these drugs. Our results show that the combination of KET and DIZ potently reduces aggression in MAOA KO mice without any PPI deficits and sedative effects. While the PPI-ameliorative properties of KET were also observed after infusion in the medial PFC (0.05 μg/side), KET did not counter the PPI-disruptive effects of Ro-256981 in MAOA KO mice. Taken together, these results point to the combination of non-subunit-selective NMDA and 5-HT2 receptor antagonists as a potential therapeutic approach for aggression and antisocial behavior with a better safety and tolerability profile than each monotherapy.
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Affiliation(s)
- Roberto Frau
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (A.P.); (V.B.)
- Guy Everett Laboratory, Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy
- Correspondence: (R.F.); (M.B.)
| | - Alessandra Pardu
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (A.P.); (V.B.)
| | - Sean Godar
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA;
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
| | - Valentina Bini
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (A.P.); (V.B.)
| | - Marco Bortolato
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
- Correspondence: (R.F.); (M.B.)
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The role of striatum and prefrontal cortex in the prevention of amphetamine-induced schizophrenia-like effects mediated by nitric oxide compounds. Prog Neuropsychopharmacol Biol Psychiatry 2018; 86:353-362. [PMID: 29555252 DOI: 10.1016/j.pnpbp.2018.03.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/14/2018] [Accepted: 03/14/2018] [Indexed: 01/07/2023]
Abstract
Pharmacological manipulation of nitric oxide (NO) has been suggested as a promising treatment for schizophrenia symptoms. A single infusion of sodium nitroprusside, a NO donor with short half-life, was found to improve schizophrenia symptoms. However, an increasing number of preclinical studies have demonstrated the potential beneficial effects of both NO donors and inhibitors. We investigated the potential synergistic effect of sub-effective doses of the NO donor sodium nitroprusside or the NO inhibitor 7-Nitroindazole (7NI) combined with clozapine, a standard atypical antipsychotic, on counteracting amphetamine or MK-801-induced psychosis-like behaviors. The impact of sodium nitroprusside and 7NI on cAMP regulation in the prefrontal cortex and striatum was also evaluated. Confirming previous results, we found that both NO donors and inhibitors prevented amphetamine-induced effects (prepulse inhibition [PPI] disruption and hyperlocomotion). In addition, we observed a synergistic effect of sodium nitroprusside and clozapine on antagonizing the disruptive effects of amphetamine, but not MK-801, in the PPI test. The sub-effective dose of 7NI tested did not prevent amphetamine or MK-induced PPI effects when combined with clozapine. Interestingly, cAMP levels were significantly decreased in the prefrontal cortex after treatment with sodium nitroprusside. In the striatum, both sodium nitroprusside and 7NI blocked the amphetamine-induced increase of cAMP. Our data corroborate previous findings on the dopaminergic mechanisms involved in the action of sodium nitroprusside. It is likely that the differential effects of sodium nitroprusside are related to its ability to modify cAMP levels in the prefrontal cortex.
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Lafioniatis A, Orfanidou MA, Papadopoulou ES, Pitsikas N. Effects of the inducible nitric oxide synthase inhibitor aminoguanidine in two different rat models of schizophrenia. Behav Brain Res 2016; 309:14-21. [PMID: 27132765 DOI: 10.1016/j.bbr.2016.04.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 04/22/2016] [Accepted: 04/26/2016] [Indexed: 10/21/2022]
Abstract
Several lines evidence indicate that the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine and the mixed dopamine (DA) D1/D2 receptor agonist apomorphine induce schizophrenia-like symptoms in rodents, including memory impairments and social withdrawal. Nitric oxide (NO) has been proposed to act as an intracellular messenger in the brain and its overproduction is associated with schizophrenia. The current study was designed to investigate the ability of the inducible NO synthase (iNOS) inhibitor aminoguanidine (AG) to counteract schizophrenia-like behavioural deficits produced by ketamine and apomorphine in rats. The efficacy of AG to antagonize extinction of recognition memory, ketamine and apomorphine-induced recognition memory impairments was tested utilizing the novel object recognition task (NORT). Further, the efficacy of AG to attenuate ketamine-induced social withdrawal was examined in the social interaction test. AG (25 and 50mg/kg) antagonized extinction of recognition memory and reversed ketamine (3mg/kg) and apomorphine (1mg/kg)-induced recognition memory deficits. In contrast, AG (50 and 100mg/kg) did not counteract the ketamine (8mg/kg)-induced social isolation. The present data show that the iNOS inhibitor AG counteracted extinction of recognition memory and reversed recognition memory deficits produced by dysfunction of the glutamatergic and the dopaminergic (DAergic) system in rats. Therefore, AG may be efficacious in attenuating memory impairments often observed in schizophrenia patients.
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Affiliation(s)
- Anastasios Lafioniatis
- Department of Pharmacology, School of Medicine, Faculty of Health Sciences, University of Thessaly, Larissa, Greece
| | - Martha A Orfanidou
- Department of Pharmacology, School of Medicine, Faculty of Health Sciences, University of Thessaly, Larissa, Greece
| | - Evangelia S Papadopoulou
- Department of Pharmacology, School of Medicine, Faculty of Health Sciences, University of Thessaly, Larissa, Greece
| | - Nikolaos Pitsikas
- Department of Pharmacology, School of Medicine, Faculty of Health Sciences, University of Thessaly, Larissa, Greece.
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Möller M, Swanepoel T, Harvey BH. Neurodevelopmental Animal Models Reveal the Convergent Role of Neurotransmitter Systems, Inflammation, and Oxidative Stress as Biomarkers of Schizophrenia: Implications for Novel Drug Development. ACS Chem Neurosci 2015; 6:987-1016. [PMID: 25794269 DOI: 10.1021/cn5003368] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Schizophrenia is a life altering disease with a complex etiology and pathophysiology, and although antipsychotics are valuable in treating the disorder, certain symptoms and/or sufferers remain resistant to treatment. Our poor understanding of the underlying neuropathological mechanisms of schizophrenia hinders the discovery and development of improved pharmacological treatment, so that filling these gaps is of utmost importance for an improved outcome. A vast amount of clinical data has strongly implicated the role of inflammation and oxidative insults in the pathophysiology of schizophrenia. Preclinical studies using animal models are fundamental in our understanding of disease development and pathology as well as the discovery and development of novel treatment options. In particular, social isolation rearing (SIR) and pre- or postnatal inflammation (PPNI) have shown great promise in mimicking the biobehavioral manifestations of schizophrenia. Furthermore, the "dual-hit" hypothesis of schizophrenia states that a first adverse event such as genetic predisposition or a prenatal insult renders an individual susceptible to develop the disease, while a second insult (e.g., postnatal inflammation, environmental adversity, or drug abuse) may be necessary to precipitate the full-blown syndrome. Animal models that emphasize the "dual-hit" hypothesis therefore provide valuable insight into understanding disease progression. In this Review, we will discuss SIR, PPNI, as well as possible "dual-hit" animal models within the context of the redox-immune-inflammatory hypothesis of schizophrenia, correlating such changes with the recognized monoamine and behavioral alterations of schizophrenia. Finally, based on these models, we will review new therapeutic options, especially those targeting immune-inflammatory and redox pathways.
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Affiliation(s)
- M. Möller
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
| | - T. Swanepoel
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
| | - B. H. Harvey
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
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Zeinoddini A, Ahadi M, Farokhnia M, Rezaei F, Tabrizi M, Akhondzadeh S. L-lysine as an adjunct to risperidone in patients with chronic schizophrenia: a double-blind, placebo-controlled, randomized trial. J Psychiatr Res 2014; 59:125-31. [PMID: 25227564 DOI: 10.1016/j.jpsychires.2014.08.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/23/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED Increasing evidence suggest that the nitric oxide signaling system of the brain may contribute to the pathophysiology of schizophrenia, making this system a target for development of novel therapeutics. The objective of this study was to investigate the efficacy and safety of L-lysine as an adjunctive to risperidone in the treatment of patients with chronic schizophrenia during an 8-week trial. Seventy-two chronic schizophrenia inpatients with a Positive and Negative Syndrome Scale (PANSS) total score of ≥ 60 participated in a randomized, double-blind, placebo-controlled trial in the active phase of their disease and underwent 8 weeks of treatment with either L-lysine (6 g/day) or placebo as an adjunctive to risperidone. Patients were evaluated using PANSS and its subscales at baseline and weeks 2, 4, 6 and 8. The primary outcome measure was to evaluate the efficacy of L-lysine in improving schizophrenia symptoms. Repeated measures analysis demonstrated significant effect for time × treatment interaction on the PANSS total (P < 0.001), negative (P < 0.001) and general psychopathology (P < 0.001) subscale scores but not the PANSS positive subscale scores (P = 0.61). The frequency of adverse events (AEs) did not differ significantly between the two treatment groups and no serious AE was observed. The present study demonstrated that l-lysine can be a tolerable and efficacious adjunctive therapy for improving negative and general psychopathology symptoms in chronic schizophrenia. However, the safety and efficacy of higher doses of l-lysine and longer treatment periods still remain unknown. TRIAL REGISTRATION Iranian registry of clinical trials (www.irct.ir): IRCT201202201556N33.
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Affiliation(s)
- Atefeh Zeinoddini
- Psychiatric Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Morvarid Ahadi
- Psychiatric Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Farokhnia
- Psychiatric Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Farzin Rezaei
- Department of Psychiatry, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Mina Tabrizi
- Department of Medical Genetics, Tehran University of Medical Sciences, Tehran, Iran
| | - Shahin Akhondzadeh
- Psychiatric Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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Abstract
The clinical symptoms and cognitive and functional deficits of schizophrenia typically begin to gradually emerge during late adolescence and early adulthood. Recent findings suggest that disturbances of a specific subset of inhibitory neurons that contain the calcium-binding protein parvalbumin (PV), which may regulate the course of postnatal developmental experience-dependent synaptic plasticity in the cerebral cortex, including the prefrontal cortex (PFC), may be involved in the pathogenesis of the onset of this illness. Specifically, converging lines of evidence suggest that oxidative stress, extracellular matrix (ECM) deficit and impaired glutamatergic innervation may contribute to the functional impairment of PV neurons, which may then lead to aberrant developmental synaptic pruning of pyramidal cell circuits during adolescence in the PFC. In addition to promoting the functional integrity of PV neurons, maturation of ECM may also play an instrumental role in the termination of developmental PFC synaptic pruning; thus, ECM deficit can directly lead to excessive loss of synapses by prolonging the course of pruning. Together, these mechanisms may contribute to the onset of schizophrenia by compromising the integrity, stability, and fidelity of PFC connectional architecture that is necessary for reliable and predictable information processing. As such, further characterization of these mechanisms will have implications for the conceptualization of rational strategies for the diagnosis, early intervention, and prevention of this debilitating disorder.
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Affiliation(s)
- Tsung-Ung W Woo
- Laboratory of Cellular Neuropathology, MRC303E, McLean Hospital, 115 Mill Street, Belmont, MA, 02478, USA,
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Critical role of nitric oxide in the modulation of prepulse inhibition in Swiss mice. Psychopharmacology (Berl) 2014; 231:663-72. [PMID: 24101156 DOI: 10.1007/s00213-013-3277-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 09/02/2013] [Indexed: 01/13/2023]
Abstract
RATIONALE Nitric oxide (NO) modulates the dopamine uptake and release processes and appears to be implicated in dopamine-related pathologies, such as schizophrenia. However, it is unclear whether there is excess or deficient NO synthesis in schizophrenia pathophysiology. Analyses of the intracellular pathways downstream of NO system activation have identified the cyclic nucleotide cyclic guanosine monophosphate (cGMP) as a possible target for drug development. Defects in the sensorimotor gating of the neural mechanism underlying the integration and processing of sensory information have been detected across species through prepulse inhibition (PPI). OBJECTIVES The aim of this study was to investigate the effects of NO/cGMP increase on sensorimotor gating modulation during dopamine hyperfunction. METHODS Mice were treated with NO donors and subjected to the PPI test. Treatment with the NO donor sodium nitroprusside was preceded by pretreatment with a soluble guanylate cyclase (sGC) inhibitor. Additionally, the mice were treated with NO donors and phosphodiesterases inhibitors prior to amphetamine treatment. RESULTS Pretreatment with the NO donors enhanced the PPI response and attenuated the amphetamine-disruptive effects on the PPI. The sGC inhibitor did not modify the sodium nitroprusside effects. Additionally, the cGMP increase induced by a specific phosphodiesterase inhibitor did not modify the amphetamine-disruptive effect. CONCLUSIONS This study provides the first demonstration that an increase in NO can improve the PPI response and block the amphetamine-disruptive effects on the PPI response. Our data are consistent with recent clinical results. However, these effects do not appear to be related to an increase in cGMP levels, and further investigation is thus required.
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Gourgiotis I, Kampouri NG, Koulouri V, Lempesis IG, Prasinou MD, Georgiadou G, Pitsikas N. Nitric oxide modulates apomorphine-induced recognition memory deficits in rats. Pharmacol Biochem Behav 2012; 102:507-14. [DOI: 10.1016/j.pbb.2012.06.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/14/2012] [Accepted: 06/18/2012] [Indexed: 02/04/2023]
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Brain nitric oxide: Regional characterisation of a real-time microelectrochemical sensor. J Neurosci Methods 2012; 209:13-21. [DOI: 10.1016/j.jneumeth.2012.05.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 05/17/2012] [Accepted: 05/21/2012] [Indexed: 11/21/2022]
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Roenker NL, Gudelsky GA, Ahlbrand R, Horn PS, Richtand NM. Evidence for involvement of nitric oxide and GABA(B) receptors in MK-801- stimulated release of glutamate in rat prefrontal cortex. Neuropharmacology 2012; 63:575-81. [PMID: 22579658 DOI: 10.1016/j.neuropharm.2012.04.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 03/23/2012] [Accepted: 04/30/2012] [Indexed: 01/18/2023]
Abstract
Systemic administration of NMDA receptor antagonists elevates extracellular glutamate within prefrontal cortex. The cognitive and behavioral effects of NMDA receptor blockade have direct relevance to symptoms of schizophrenia, and recent studies demonstrate an important role for nitric oxide and GABA(B) receptors in mediating the effects of NMDA receptor blockade on these behaviors. We sought to extend those observations by directly measuring the effects of nitric oxide and GABA(B) receptor mechanisms on MK-801-induced glutamate release in the prefrontal cortex. Systemic MK-801 injection (0.3 mg/kg) to male Sprague-Dawley rats significantly increased extracellular glutamate levels in prefrontal cortex, as determined by microdialysis. This effect was blocked by pre-treatment with the nitric oxide synthase inhibitor L-NAME (60 mg/kg). Reverse dialysis of the nitric oxide donor SNAP (0.5-5 mM) directly into prefrontal cortex mimicked the effect of systemic MK-801, dose-dependently elevating cortical extracellular glutamate. The effect of MK-801 was also blocked by systemic treatment with the GABA(B) receptor agonist baclofen (5 mg/kg). In combination, these data suggest increased nitric oxide formation is necessary for NMDA antagonist-induced elevations of extracellular glutamate in the prefrontal cortex. Additionally, the data suggest GABA(B) receptor activation can modulate the NMDA antagonist-induced increase in cortical glutamate release.
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Affiliation(s)
- Nicole L Roenker
- James Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH 45267, USA.
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Venkatasubramanian G. Nitric oxide synthase mediation of darbepoetin's cognitive benefits: a paradoxical effect? Neuropsychopharmacology 2012; 37:1074; author reply 1075. [PMID: 22327905 PMCID: PMC3280637 DOI: 10.1038/npp.2011.270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ganesan Venkatasubramanian
- The Metabolic Clinic in Psychiatry, Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore, India,The Metabolic Clinic in Psychiatry, Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore 560029, India, Tel: +00 91 80 26995256, Fax: +00 91 80 26564830, E-mail:
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Rose EJ, Greene C, Kelly S, Morris DW, Robertson IH, Fahey C, Jacobson S, O'Doherty J, Newell FN, McGrath J, Bokde A, Garavan H, Frodl T, Gill M, Corvin AP, Donohoe G. The NOS1 variant rs6490121 is associated with variation in prefrontal function and grey matter density in healthy individuals. Neuroimage 2011; 60:614-22. [PMID: 22227051 DOI: 10.1016/j.neuroimage.2011.12.054] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 12/16/2011] [Accepted: 12/19/2011] [Indexed: 12/12/2022] Open
Abstract
A common polymorphism within the nitric oxide sythanse-1 (NOS1) gene (rs6490121), initially identified as risk variant for schizophrenia, has been associated with variation in working memory and IQ. Here we investigated how this variation might be mediated at the level of brain structure and function. In healthy individuals (N=157), voxel based morphometry was used to compare grey matter (GM) volume between homozygous and heterozygous carriers of the 'G' allele (i.e. the allele associated with impaired cognition and schizophrenia risk) and homozygous carriers of the non-risk 'A' allele. Functional brain imaging data were also acquired from 48 participants during performance of a spatial working memory (SWM) task, and analysed to determine any effect of NOS1 risk status. An a priori region-of-interest analysis identified a significant reduction in ventromedial prefrontal GM volume in 'G' allele carriers. Risk carriers also exhibited altered patterns of activation in the prefrontal cortex, caudate, and superior parietal lobe, which were characteristic of abnormal increases in activation in frontoparietal working memory networks and a failure to disengage regions of the default mode network. These functional changes suggest a NOS1-mediated processing inefficiency, which may contribute to cognitive dysfunction in schizophrenia. While the mechanisms by which NOS1 may influence brain structure and/or function have not yet been well delineated, these data provide further evidence for a role of NOS1 in risk for schizophrenia via an impact upon cognitive function.
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Affiliation(s)
- Emma J Rose
- Neuropsychiatric Genetics Research Group & Institute of Molecular Medicine, Department of Psychiatry, Trinity College Dublin, Ireland.
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Salum C, Issy AC, Brandão ML, Guimarães FS, Bel EAD. Nitric oxide modulates dopaminergic regulation of prepulse inhibition in the basolateral amygdala. J Psychopharmacol 2011; 25:1639-48. [PMID: 20837567 DOI: 10.1177/0269881110379282] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Systemic injection of the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine (LNO) prevents the disruptive effect of amphetamine (Amph) on prepulse inhibition (PPI), a sensorimotor gating model in which the amplitude of the acoustic startle response (ASR) to a startling sound (pulse) is reduced when preceded immediately by a weaker stimulus (prepulse). Given that dopamine (DA) projections to the basolateral amygdala (BLA) are involved in the control of information processing, our aim was to investigate if intra-BLA administration of LNO would modify the disruption caused by the DA agonists, Amph, apomorphine (Apo) and quinpirole (QNP), on PPI. Male Wistar rats received bilateral intra-BLA microinjections (0.2 µL/min/side) of combined treatments (saline or LNO 11 µg followed by saline, QNP 3 µg, Apo 10 µg or Amph 30 µg). PPI was disrupted by intra-BLA Apo, QNP or Amph but not by LNO. Prior bilateral intra-BLA injection of LNO prevented the Apo- and QNP-induced disruption of PPI but did not affect that caused by Amph. APO- or QNP-induced increases in ASR to prepulse + pulse were also restored by LNO. Since local inhibition of NO formation affected the effects of direct, but not indirect, DA agonists, the results suggest that this modulation is not occurring at the level of DA release but may involve complex interactions with other neurotransmitter systems.
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Affiliation(s)
- C Salum
- Centro de Matemática, Computação e Cognição, Núcleo de Cognição e Sistemas Complexos, Universidade Federal do ABC, São Paulo, Brazil.
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O'Donoghue T, Morris DW, Fahey C, Da Costa A, Foxe JJ, Hoerold D, Tropea D, Gill M, Corvin A, Donohoe G. A NOS1 variant implicated in cognitive performance influences evoked neural responses during a high density EEG study of early visual perception. Hum Brain Mapp 2011; 33:1202-11. [PMID: 21520349 DOI: 10.1002/hbm.21281] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 01/06/2011] [Accepted: 01/13/2011] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND The nitric oxide synthasase-1 gene (NOS1) has been implicated in mental disorders including schizophrenia and variation in cognition. The NOS1 variant rs6490121 identified in a genome wide association study of schizophrenia has recently been associated with variation in general intelligence and working memory in both patients and healthy participants. Whether this variant is also associated with variation in early sensory processing remains unclear. METHODS We investigated differences in the P1 visual evoked potential in a high density EEG study of 54 healthy participants. Given both NOS1's association with cognition and recent evidence that cognitive performance and P1 response are correlated, we investigated whether NOS1's effect on P1 response was independent of its effects on cognition using CANTAB's spatial working memory (SWM) task. RESULTS We found that carriers of the previously identified risk "G" allele showed significantly lower P1 responses than non-carriers. We also found that while P1 response and SWM performance were correlated, NOS1 continued to explain a significant proportion of variation in P1 response even when its effects on cognition were accounted for. CONCLUSION The schizophrenia implicated NOS1 variants rs6490121 influences visual sensory processing as measured by the P1 response, either as part of the gene's pleiotropic effects on multiple aspects of brain function, or because of a primary influence on sensory processing that mediates the effects already seen in higher cognitive processes.
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Affiliation(s)
- Therese O'Donoghue
- Neuropsychiatric Genetics Group and Department of Psychiatry, Institute of Molecular Medicine, Trinity College Dublin, St. James Hospital, Dublin 8, Ireland
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Wass C, Klamer D, Katsarogiannis E, Pålsson E, Svensson L, Fejgin K, Bogren IB, Engel JA, Rembeck B. L-lysine as adjunctive treatment in patients with schizophrenia: a single-blinded, randomized, cross-over pilot study. BMC Med 2011; 9:40. [PMID: 21501494 PMCID: PMC3094237 DOI: 10.1186/1741-7015-9-40] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 04/18/2011] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Accumulating evidence suggests that the brain's nitric oxide (NO) signalling system may be involved in the pathophysiology of schizophrenia and could thus constitute a novel treatment target. The study was designed to investigate the benefit of L-lysine, an amino acid that interferes with NO production, as an add-on treatment for schizophrenia. METHODS L-lysine, 6 g/day, was administered to 10 patients with schizophrenia as an adjunctive to their conventional antipsychotic medication. The study was designed as a single-blinded, cross-over study where patients were randomly assigned to initial treatment with either L-lysine or placebo and screened at baseline, after four weeks when treatment was crossed over, and after eight weeks. RESULTS L-lysine treatment caused a significant increase in blood concentration of L-lysine and was well tolerated. A significant decrease in positive symptom severity, measured by the Positive And Negative Syndrome Scale (PANSS), was detected. A certain decrease in score was also observed during placebo treatment and the effects on PANSS could not unequivocally be assigned to the L-lysine treatment. Furthermore, performance on the Wisconsin Card Sorting Test was significantly improved compared to baseline, an effect probably biased by training. Subjective reports from three of the patients indicated decreased symptom severity and enhanced cognitive functioning. CONCLUSIONS Four-week L-lysine treatment of 6 g/day caused a significant increase in blood concentration of L-lysine that was well tolerated. Patients showed a significant decrease in positive symptoms as assessed by PANSS in addition to self-reported symptom improvement by three patients. The NO-signalling pathway is an interesting, potentially new treatment target for schizophrenia; however, the effects of L-lysine need further evaluation to decide the amino acid's potentially beneficial effects on symptom severity in schizophrenia.
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Affiliation(s)
- Caroline Wass
- Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Canada.
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Klamer D, Svensson L, Fejgin K, Pålsson E. Prefrontal NMDA receptor antagonism reduces impairments in pre-attentive information processing. Eur Neuropsychopharmacol 2011; 21:248-53. [PMID: 21111580 DOI: 10.1016/j.euroneuro.2010.10.010] [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: 08/30/2010] [Revised: 10/19/2010] [Accepted: 10/19/2010] [Indexed: 10/18/2022]
Abstract
A well established theory proposes that glutamate signalling via the NMDA receptor is compromised in patients with schizophrenia. Deficits related to NMDA receptor signalling can be observed in several brain regions including the prefrontal cortex (PFC), an area extensively linked to the cognitive dysfunction in this disease and notably affected by NMDA receptor antagonists such as phencyclidine (PCP). In addition, a number of studies suggest that normalizing of PFC function could constitute a treatment rationale for schizophrenia. To further study the role of PFC function we investigated the effect of local PFC NMDA receptor blockade on impaired prepulse inhibition (PPI) induced by systemic administration of PCP. Mice received prefrontal injections of PCP (0.01, 0.1 or 1mM) before PCP treatment (5mg/kg) and were thereafter tested for PPI. PCP induced deficits in PPI were ameliorated by prefrontal PCP (0.1mM) treatment whereas PPI was not affected by prefrontal cortex PCP administration per se at any of the doses tested. Taken together, inhibition of NMDA receptors in the PFC does not seem to be enough to impair PPI per se but NMDA receptor mediated signalling in the PFC may be a key factor for the PPI-disruptive effects of global NMDA receptor inhibition. This indicates that targeting PFC NMDA receptor signalling may have potential as a treatment target for schizophrenia although further studies are needed to understand pharmacology and pathophysiological role of PFC NMDA receptors.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg,Gothenburg, Sweden
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Information processing deficits and nitric oxide signalling in the phencyclidine model of schizophrenia. Psychopharmacology (Berl) 2010; 212:643-51. [PMID: 20802999 DOI: 10.1007/s00213-010-1992-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 08/04/2010] [Indexed: 12/22/2022]
Abstract
RATIONALE Schizophrenia-like cognitive deficits induced by phencyclidine (PCP), a drug commonly used to model schizophrenia in experimental animals, are attenuated by nitric oxide (NO) synthase inhibitors. Furthermore, PCP increases NO levels and sGC/cGMP signalling in the prefrontal cortex in rodents. Hence, a cortical NO/sGC/cGMP signalling pathway may constitute a target for novel pharmacological therapies in schizophrenia. OBJECTIVES The objective of this study was to further investigate the role of NO signalling for a PCP-induced deficit in pre-attentive information processing. MATERIALS AND METHODS Male Sprague-Dawley rats were surgically implanted with NO-selective amperometric microsensors aimed at the prefrontal cortex, ventral hippocampus or nucleus accumbens, and NO levels and prepulse inhibition (PPI) were simultaneously assessed. RESULTS PCP treatment increased NO levels in the prefrontal cortex and ventral hippocampus, but not in the nucleus accumbens. The increase in NO levels was not temporally correlated to the deficit in PPI induced by PCP. Furthermore, pretreatment with the neuronal NO synthase inhibitor N-propyl-L-arginine dose-dependently attenuated both the increase in prefrontal cortex NO levels and the deficit in PPI. CONCLUSIONS These findings support a demonstrated role of NO in the behavioural and neurochemical effects of PCP. Furthermore, this effect is brain region-specific and mainly involves the neuronal isoform of NOS. However, a temporal correlation between a PCP-induced disruption of PPI and an increase in prefrontal cortex NO levels was not demonstrated, suggesting that the interaction between PCP and the NO system is more complex than previously thought.
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Issy AC, Lazzarini M, Szawka RE, Carolino ROG, Anselmo-Franci JA, Del Bel EA. Nitric oxide synthase inhibitors improve prepulse inhibition responses of Wistar rats. Behav Brain Res 2010; 217:416-23. [PMID: 21074571 DOI: 10.1016/j.bbr.2010.11.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 10/20/2010] [Accepted: 11/05/2010] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Cognitive and attentional deficits in schizophrenia include impairment of the sensorimotor filter as measured by prepulse inhibition (PPI). In this way, the study of animals that naturally present low PPI responses could be a useful approach for screening new antipsychotic drugs. Several pieces of evidence suggest that dopamine and nitric oxide (NO) can modulate PPI but their role in those animals is unknown. OBJECTIVES The aim of this study was to investigate the role of dopamine and NO in Wistar rats with naturally low PPI response. METHODS Male Wistar rats with low PPI responses received an i.p. injection of the antipsychotics haloperidol (0.1, 0.3 or 1mg/kg) or clozapine (0.5, 1.5 or 5mg/kg), the anxiolytic diazepam (1 or 3mg/kg) or the NO synthase (NOS) inhibitors, N(G)- nitro-l-arginine (l-NOARG; 40mg/kg, acutely or sub-chronically) or 7-Nitroindazole (7-NI; 3, 10 or 30mg/kg). All animals were submitted to the PPI test 1h after injection. Striatal and cortical dopamine, DOPAC, and noradrenaline levels of rats with low PPI responses were compared to rats with normal PPI responses. RESULTS We found increased levels of catecholamines on the striatum and prefrontal cortex of Wistar rats with low PPI. In these animals, both antipsychotics, typical and atypical, and NOS inhibitors significantly increased PPI. CONCLUSION Taken together, our findings suggest that the low PPI phenotype may be driven by an overactive catecholamine system. Additionally, our results corroborate the hypothesis of dopamine and NO interaction on PPI modulation and suggest that Wistar rats with low PPI may represent an interesting non-pharmacological model to evaluate new potential antipsychotics.
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Affiliation(s)
- A C Issy
- Department of Pharmacology, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP, Brazil
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Boultadakis A, Pitsikas N. Effects of the nitric oxide synthase inhibitor L-NAME on recognition and spatial memory deficits produced by different NMDA receptor antagonists in the rat. Neuropsychopharmacology 2010; 35:2357-66. [PMID: 20664579 PMCID: PMC3055326 DOI: 10.1038/npp.2010.109] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is consistent experimental evidence that noncompetitive antagonists of the N-methyl-D-aspartate (NMDA) receptor, such as ketamine, MK-801, and phencyclidine (PCP), impair cognition and produce psychotomimetic effects in rodents. Nitric oxide (NO) is considered as an intracellular messenger in the brain. The implication of NO in learning and memory is well documented. This study was designed to investigate the ability of the NO synthase inhibitor L-NAME to antagonize recognition and spatial memory deficits produced by the NMDA receptor antagonists, MK-801 and ketamine, in the rat. L-NAME (1-3 mg/kg) counteracted MK-801- (0.1 mg/kg) and ketamine (3 mg/kg)-induced performance impairments in the novel object recognition task. L-NAME (10 mg/kg) attenuated ketamine (15 mg/kg)-induced spatial working memory and retention deficits in the radial water maze paradigm. L-NAME, applied at 3 mg/kg, however, disrupted rodents' performance in this spatial memory task. The present findings indicate (1) that L-NAME is sensitive to glutamate hypofunction produced by other than PCP NMDA antagonists such as MK-801 and ketamine and (2) that L-NAME alone differentially affects rodents' spatial memory.
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Affiliation(s)
- Antonios Boultadakis
- Department of Pharmacology, School of Medicine, University of Thessaly, Larissa, Greece
| | - Nikolaos Pitsikas
- Department of Pharmacology, School of Medicine, University of Thessaly, Larissa, Greece,Department of Pharmacology, School of Medicine, University of Thessaly, Biopolis, 411-10 Larissa, Greece. Tel: +30 2410 685535, Fax: +30 2410 685552; E-mail:
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Bitanihirwe BKY, Woo TUW. Oxidative stress in schizophrenia: an integrated approach. Neurosci Biobehav Rev 2010; 35:878-93. [PMID: 20974172 DOI: 10.1016/j.neubiorev.2010.10.008] [Citation(s) in RCA: 311] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 09/18/2010] [Accepted: 10/17/2010] [Indexed: 01/17/2023]
Abstract
Oxidative stress has been suggested to contribute to the pathophysiology of schizophrenia. In particular, oxidative damage to lipids, proteins, and DNA as observed in schizophrenia is known to impair cell viability and function, which may subsequently account for the deteriorating course of the illness. Currently available evidence points towards an alteration in the activities of enzymatic and nonenzymatic antioxidant systems in schizophrenia. In fact, experimental models have demonstrated that oxidative stress induces behavioral and molecular anomalies strikingly similar to those observed in schizophrenia. These findings suggest that oxidative stress is intimately linked to a variety of pathophysiological processes, such as inflammation, oligodendrocyte abnormalities, mitochondrial dysfunction, hypoactive N-methyl-d-aspartate receptors and the impairment of fast-spiking gamma-aminobutyric acid interneurons. Such self-sustaining mechanisms may progressively worsen producing the functional and structural consequences associated with schizophrenia. Recent clinical studies have shown antioxidant treatment to be effective in ameliorating schizophrenic symptoms. Hence, identifying viable therapeutic strategies to tackle oxidative stress and the resulting physiological disturbances provide an exciting opportunity for the treatment and ultimately prevention of schizophrenia.
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Affiliation(s)
- Byron K Y Bitanihirwe
- Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology, Zurich, Schorenstrasse 16, Schwerzenbach CH 8603, Switzerland.
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Uzbay T, Kayir H, Goktalay G, Yildirim M. Agmatine disrupts prepulse inhibition of acoustic startle reflex in rats. J Psychopharmacol 2010; 24:923-9. [PMID: 19282421 DOI: 10.1177/0269881109102533] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Agmatine is a guanidine-amine formed by the enzymatic decarboxylation of arginine. Agmatine has been proposed to be a neuromodulator and its downstream derivatives, the polyamines, have been suggested to be responsible for sensory gating deficits seen in schizophrenia. In this study, male Wistar rats underwent treatments with agmatine, vehicle or other agents known to alter sensory gating in an experimental paradigm of prepulse inhibition (PPI) of the acoustic startle response. Apomorphine (1 mg/kg s.c.), a nonselective dopamine agonist known to disrupt PPI responses, was injected as the positive reference. Neither apomorphine nor agmatine (40-160 mg/kg i.p.) induced effects on the intensity of startle reflex without a prepulse. However, apomorphine or agmatine (160 mg/kg i.p.) disrupted the PPI of acoustic startle reflex. Furthermore, when given 30 min prior, agmatine acted additively with apomorphine's effect on PPI. In an attempt to gain more insight, haloperidol (1 and 2 mg/kg i.p.), clozapine (2.5-7.5 mg/kg i.p.) or quetiapine (2.5 and 7.5 mg/kg i.p.) was also injected prior to agmatine (160 mg/kg i.p.). Haloperidol (1 mg/kg) and clozapine (2.5 and 5 mg/kg) were able to prevent the PPI-disrupting effects of apomorphine. However, none of these antipsychotics prevent the PPI-disrupting effects of agmatine. These results suggest that agmatine disrupts the PPI of acoustic startle reflex of rats in a fundamentally different manner than apomorphine does. It may also have a critical role in the pathogenesis of sensorimotor gating-related dysfunctions.
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Affiliation(s)
- T Uzbay
- Gulhane Military Medical Academy, Faculty of Medicine, Department of Medical Pharmacology, Psychopharmacology Research Unit, Ankara, Turkey.
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Pålsson E, Finnerty N, Fejgin K, Klamer D, Wass C, Svensson L, Lowry J. Increased cortical nitric oxide release after phencyclidine administration. Synapse 2009; 63:1083-8. [DOI: 10.1002/syn.20690] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Tanda K, Nishi A, Matsuo N, Nakanishi K, Yamasaki N, Sugimoto T, Toyama K, Takao K, Miyakawa T. Abnormal social behavior, hyperactivity, impaired remote spatial memory, and increased D1-mediated dopaminergic signaling in neuronal nitric oxide synthase knockout mice. Mol Brain 2009; 2:19. [PMID: 19538708 PMCID: PMC2711944 DOI: 10.1186/1756-6606-2-19] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Accepted: 06/18/2009] [Indexed: 12/26/2022] Open
Abstract
Background Neuronal nitric oxide synthase (nNOS) is involved in the regulation of a diverse population of intracellular messenger systems in the brain. In humans, abnormal NOS/nitric oxide metabolism is suggested to contribute to the pathogenesis and pathophysiology of some neuropsychiatric disorders, such as schizophrenia and bipolar disorder. Mice with targeted disruption of the nNOS gene exhibit abnormal behaviors. Here, we subjected nNOS knockout (KO) mice to a battery of behavioral tests to further investigate the role of nNOS in neuropsychiatric functions. We also examined the role of nNOS in dopamine/DARPP-32 signaling in striatal slices from nNOS KO mice and the effects of the administration of a dopamine D1 receptor agonist on behavior in nNOS KO mice. Results nNOS KO mice showed hyperlocomotor activity in a novel environment, increased social interaction in their home cage, decreased depression-related behavior, and impaired spatial memory retention. In striatal slices from nNOS KO mice, the effects of a dopamine D1 receptor agonist, SKF81297, on the phosphorylation of DARPP-32 and AMPA receptor subunit GluR1 at protein kinase A sites were enhanced. Consistent with the biochemical results, intraperitoneal injection of a low dose of SKF81297 significantly decreased prepulse inhibition in nNOS KO mice, but not in wild-type mice. Conclusion These findings indicate that nNOS KO upregulates dopamine D1 receptor signaling, and induces abnormal social behavior, hyperactivity and impaired remote spatial memory. nNOS KO mice may serve as a unique animal model of psychiatric disorders.
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Affiliation(s)
- Koichi Tanda
- Genetic Engineering and Functional Genomics Group, Horizontal Medical Research Organization, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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Prefrontal GABA(B) receptor activation attenuates phencyclidine-induced impairments of prepulse inhibition: involvement of nitric oxide. Neuropsychopharmacology 2009; 34:1673-84. [PMID: 19145229 DOI: 10.1038/npp.2008.225] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent theories propose that both GABA and glutamate signaling are compromised in patients with schizophrenia. These deficits can be observed in several brain regions including the prefrontal cortex (PFC), an area extensively linked to the cognitive dysfunction in this disease and notably affected by NMDA receptor antagonists such as phencyclidine (PCP). We have previously demonstrated that inhibition of the nitric oxide (NO) pathways in the brain, particularly in the PFC, prevents a wide range of PCP-induced behavioral deficits including disruption of prepulse inhibition (PPI). This study investigated the role of GABA(B) receptor signaling and NO in the effects of PCP on PPI. Mice received systemic or prefrontal injections of the GABA(B) receptor agonist baclofen (2.5-5 mg/kg and 1 mM) before PCP treatment (5 mg/kg) and were thereafter tested for PPI. GABA/NO interactions were studied by combining baclofen and the NO synthase inhibitor L-NAME (20 mg/kg) in subthreshold doses. The role of GABA(B) receptors for NO production in vivo was assessed using NO-sensors implanted into the rat PFC. PCP-induced PPI deficits were attenuated in an additive manner by systemic baclofen treatment, whereas prefrontal microinjections of baclofen completely blocked the effects of PCP, without affecting PPI per se. The combination of baclofen and L-NAME was more effective in preventing the effects of PCP than any compound by itself. Additionally, baclofen decreased NO release in the PFC in a dose-related manner. This study proposes a role for GABA(B) receptor signaling in the effects of PCP, with altered NO levels as a downstream consequence. Thus, prefrontal NO signaling mirrors an altered level of cortical inhibition that may be of importance for information processing deficits in schizophrenia.
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Agmatine attenuates the disruptive effects of phencyclidine on prepulse inhibition. Eur J Pharmacol 2008; 590:212-6. [DOI: 10.1016/j.ejphar.2008.06.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 05/26/2008] [Accepted: 06/05/2008] [Indexed: 12/18/2022]
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Fejgin K, Pålsson E, Wass C, Svensson L, Klamer D. Nitric oxide signaling in the medial prefrontal cortex is involved in the biochemical and behavioral effects of phencyclidine. Neuropsychopharmacology 2008; 33:1874-83. [PMID: 17895915 DOI: 10.1038/sj.npp.1301587] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The prefrontal cortex (PFC) is believed to play an important role in the cognitive impairments observed in schizophrenia and has also been shown to be involved in the modulation of prepulse inhibition (PPI), a measure of preattentive information processing that is impaired in schizophrenic individuals. Phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor, exerts psychotomimetic effects in humans, disrupts PPI, and causes hypofrontality in rodents and monkeys. We have previously demonstrated that interfering with the production of nitric oxide (NO) can prevent a wide range of PCP-induced behavioral deficits, including PPI disruption. In the present study, the role of NO signaling for the behavioral and biochemical effects of PCP was further investigated. Dialysate from the medial PFC of mice receiving systemic treatment with PCP and/or the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 40 mg/kg), was analyzed for cGMP content. Furthermore, a specific inhibitor of NO-sensitive soluble guanylyl cyclase (sGC), 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ, 0.01-1 mM), was administered into the medial PFC of mice in combination with systemic injections of PCP, followed by PPI and locomotor activity testing. PCP (5 mg/kg) caused an increase in prefrontal cGMP that could be attenuated by pretreatment with the NO synthase inhibitor, L-NAME. Moreover, bilateral microinjection of the sGC inhibitor, ODQ, into the medial PFC of mice attenuated the disruption of PPI, but not the hyperlocomotion, caused by PCP. The present study shows that NO/sGC/cGMP signaling pathway in the medial PFC is involved in specific behavioral effects of PCP that may have relevance for the disabling cognitive dysfunction found in patients with schizophrenia.
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Affiliation(s)
- Kim Fejgin
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
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Nitric oxide synthase inhibition attenuates phencyclidine-induced disruption of cognitive flexibility. Pharmacol Biochem Behav 2008; 89:352-9. [PMID: 18321564 DOI: 10.1016/j.pbb.2008.01.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 01/07/2008] [Accepted: 01/14/2008] [Indexed: 11/22/2022]
Abstract
Schizophrenia encompasses, amongst other symptoms, a heavy load of cognitive dysfunctionality. Using the psychotomimetic agent, phencyclidine (PCP), we have previously found that PCP-induced disruptions of cognitive function in translational rodent models of schizophrenia are dependent on nitric oxide (NO) production. In the present study, male Sprague-Dawley rats were subjected to a Morris water maze task designed to assess cognitive flexibility (i.e. the ability to cope with an increasingly demanding cognitive task) by means of a "constant reversal learning paradigm". Experiments were conducted to evaluate the effects of the NO synthase inhibitor, L-NAME (10 mg/kg), on PCP-induced (2 mg/kg) impairments. Control animals significantly improved their learning over the first 3 consecutive days, whereas PCP-treated animals failed to show any significant learning. Pretreatment with L-NAME normalized the PCP-induced disruption of learning to control levels. These findings suggest that PCP-induced disruptions of cognitive flexibility (i.e. ability to modify behaviour according to an increasingly demanding cognitive task) are dependent upon NO production. These observations, together with accumulated clinical findings, suggest that the NO system is a potential treatment target for cognitive dysfunctions in schizophrenia.
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Pålsson E, Fejgin K, Wass C, Engel JA, Svensson L, Klamer D. The amino acid L-lysine blocks the disruptive effect of phencyclidine on prepulse inhibition in mice. Psychopharmacology (Berl) 2007; 192:9-15. [PMID: 17235609 DOI: 10.1007/s00213-006-0683-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 12/15/2006] [Indexed: 11/24/2022]
Abstract
RATIONALE The cognitive and attentional deficits observed in schizophrenic patients are now considered central to the pathophysiology of the disorder. These deficits include an inability to filter sensory input as measured by, e.g., prepulse inhibition (PPI) reflex. Administration of phencyclidine (PCP), a drug that can induce a schizophrenia-like psychosis in humans, disrupts PPI in experimental animals. In rodents, this PCP-induced deficit can be blocked by pretreatment with nitric oxide (NO) synthase inhibitors. This suggests that some of the behavioral effects of PCP are mediated via NO. The substrate for in vivo NO production is L-arginine, and active transport of L-arginine via the cationic amino acid transporter may serve as a regulatory mechanism in NO production. OBJECTIVES The aim of the present study was to study the effects of L-arginine transport inhibition, using acute and repeated L-lysine treatment, on PCP-induced disruption of PPI in mice. RESULTS Subchronic, and to some extent acute, pretreatment with L-lysine blocked a PCP-induced deficit in PPI without affecting basal PPI. CONCLUSIONS L-lysine has been shown to block L-arginine transport in vitro, most likely via a competitive blockade and down regulation of cationic amino acid transporters. However, the importance of L-arginine transport as a regulatory mechanism in NO production in vivo is still not clear. The present results lend further support to the notion that some of the effects of PCP in the central nervous system are mediated via NO and that L-arginine transport may play a role in the regulation of NO production in the brain.
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Affiliation(s)
- Erik Pålsson
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Göteborg University, POB 431, 405 30, Göteborg, Sweden
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Fejgin K, Safonov S, Pålsson E, Wass C, Engel JA, Svensson L, Klamer D. The atypical antipsychotic, aripiprazole, blocks phencyclidine-induced disruption of prepulse inhibition in mice. Psychopharmacology (Berl) 2007; 191:377-85. [PMID: 17235612 DOI: 10.1007/s00213-006-0658-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Accepted: 11/24/2006] [Indexed: 12/23/2022]
Abstract
RATIONALE The psychotomimetic drug, phencyclidine, induces schizophrenia-like behavioural changes in both humans and animals. Phencyclidine-induced disruption of sensory motor gating mechanisms, as assessed by prepulse inhibition of the acoustic startle, is widely used in research animals as a screening model for antipsychotic properties in general and may predict effects on negative and cognitive deficits in particular. Dopamine (DA) stabilizers comprise a new generation of antipsychotics characterized by a partial DA receptor agonist or antagonist action and have been suggested to have a more favourable clinical profile. OBJECTIVE The aim of the present study was to investigate the ability of first, second and third generation antipsychotics to interfere with the disruptive effect of phencyclidine on prepulse inhibition in mice. RESULTS Aripiprazole blocked the phencyclidine-induced disruption of prepulse inhibition. The atypical antipsychotic clozapine was less effective, whereas olanzapine, and the typical antipsychotic haloperidol, failed to alter the effects of phencyclidine on prepulse inhibition. CONCLUSIONS The somewhat superior efficacy of clozapine compared to haloperidol may be explained by its lower affinity and faster dissociation rate for DA D2 receptors possibly combined with an interaction with other receptor systems. Aripiprazole was found to be more effective than clozapine or olanzapine, which may be explained by a partial agonist activity of aripiprazole at DA D2 receptors. In conclusion, the present findings suggest that partial DA agonism leading to DA stabilizing properties may have favourable effects on sensorimotor gating and thus tentatively on cognitive dysfunctions in schizophrenia.
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Affiliation(s)
- Kim Fejgin
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy, Göteborg University, P.O. Box 431, SE 405 30, Göteborg, Sweden
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Wass C, Archer T, Pålsson E, Fejgin K, Klamer D, Engel JA, Svensson L. Effects of phencyclidine on spatial learning and memory: Nitric oxide-dependent mechanisms. Behav Brain Res 2006; 171:147-53. [PMID: 16677724 DOI: 10.1016/j.bbr.2006.03.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 03/20/2006] [Accepted: 03/27/2006] [Indexed: 10/24/2022]
Abstract
Cognitive deficits of schizophrenia constitute a disabling part of the disease predicting treatment success as well as functional outcome. Phencyclidine (PCP), a non-competitive NMDA receptor antagonist was used to model schizophrenic cognitive dysfunctions of learning and memory using the Morris water maze paradigm for reference memory. In experiment 1 male Sprauge-Dawley rats were acutely administered PCP (0.5, 1.0 and 2.0 mg/kg s.c.) before the first swim session on each of the four acquisition days. Probe test for reference memory was performed 2 days after the last acquisition day; the first probe without drug treatment to assess reference memory and a second probe with prior drug treatment to control for state dependency effects of PCP. In experiment 2 the effects of pre-treatment (10 min before PCP) with the nitric oxide synthase inhibitor, L-NAME (10 mg/kg s.c.), on the PCP (2 mg/kg)-induced spatial memory deficit was evaluated in the Morris water maze paradigm for reference memory. The results showed that PCP in a dose of 2 mg/kg disrupts spatial learning as estimated by prolonged search time to find platform during acquisition as well as the reference memory test as measured by less time spent in target quadrant during probe trial. No state dependency effects of PCP were found. Pre-treatment with L-NAME completely reversed the PCP-induced disruption of acquisition learning. The reference memory disruption was, however, not completely restored as measured by probe trial.
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Affiliation(s)
- Caroline Wass
- Department of Pharmacology, The Sahlgrenska Academy at Göteborg University, Sweden
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Reif A, Herterich S, Strobel A, Ehlis AC, Saur D, Jacob CP, Wienker T, Töpner T, Fritzen S, Walter U, Schmitt A, Fallgatter AJ, Lesch KP. A neuronal nitric oxide synthase (NOS-I) haplotype associated with schizophrenia modifies prefrontal cortex function. Mol Psychiatry 2006; 11:286-300. [PMID: 16389274 DOI: 10.1038/sj.mp.4001779] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nitric oxide (NO) is a gaseous neurotransmitter thought to play important roles in several behavioral domains. On a neurobiological level, NO acts as the second messenger of the N-methyl-D-aspartate receptor and interacts with both the dopaminergic as well as the serotonergic system. Thus, NO is a promising candidate molecule in the pathogenesis of endogenous psychoses and a potential target in their treatment. Furthermore, the chromosomal locus of the gene for the NO-producing enzyme NOS-I, 12q24.2, represents a major linkage hot spot for schizophrenic and bipolar disorder. To investigate whether the gene encoding NOS-I (NOS1) conveys to the genetic risk for those diseases, five NOS1 polymorphisms as well as a NOS1 mini-haplotype, consisting of two functional polymorphisms located in the transcriptional control region of NOS1, were examined in 195 chronic schizophrenic, 72 bipolar-I patients and 286 controls. Single-marker association analysis showed that the exon 1c promoter polymorphism was linked to schizophrenia (SCZ), whereas synonymous coding region polymorphisms were not associated with disease. Long promoter alleles of the repeat polymorphism were associated with less severe psychopathology. Analysis of the mini-haplotype also revealed a significant association with SCZ. Mutational screening did not detect novel exonic polymorphisms in patients, suggesting that regulatory rather than coding variants convey the genetic risk on psychosis. Finally, promoter polymorphisms impacted on prefrontal functioning as assessed by neuropsychological testing and electrophysiological parameters elicited by a Go-Nogo paradigm in 48 patients (continuous performance test). Collectively these findings suggest that regulatory polymorphisms of NOS1 contribute to the genetic risk for SCZ, and modulate prefrontal brain functioning.
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Affiliation(s)
- A Reif
- Department of Psychiatry and Psychotherapy (Section for Clinical and Molecular Psychobiology and Laboratory for Psychophysiology and Functional Imaging), Julius-Maximilians-University Würzburg, Würzburg, Germany.
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Pitsikas N, Zisopoulou S, Sakellaridis N. Nitric oxide donor molsidomine attenuates psychotomimetic effects of the NMDA receptor antagonist MK-801. J Neurosci Res 2006; 84:299-305. [PMID: 16710846 DOI: 10.1002/jnr.20889] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
There is experimental evidence indicating that the non-competitive NMDA receptor antagonist MK-801 impairs cognition and produces a series of schizophrenia-like symptoms in rodents (hypermotility, stereotypies, and ataxia). The present study was designed to investigate the efficacy of the nitric oxide (NO) donor molsidomine in counteracting these MK-801-induced behavioral effects in the rat. In a first study, post-training administration of molsidomine (at 4 but not 2 mg/kg) successfully antagonized MK-801-induced performance deficits in a recognition memory test. In a subsequent study, molsidomine (2 and 4 mg/kg) was shown to be unable to reverse MK-801-induced hypermotility but attenuated stereotypies (continuous movement whole cage, body sway, and head weaving) produced by MK-801. Moreover, at 4 mg/kg this NO donor counteracted MK-801-induced ataxia. Our findings indicate that molsidomine attenuates behavioral effects related to the hypofunction of the NMDA receptor suggesting that NO might be involved in the psychotomimetic effects of non-competitive NMDA receptor antagonists.
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Affiliation(s)
- Nikolaos Pitsikas
- Department of Pharmacology, School of Medicine, University of Thessaly, Larissa, Greece.
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Klamer D, Engel JA, Svensson L. Effects of phencyclidine on acoustic startle and prepulse inhibition in neuronal nitric oxide synthase deficient mice. Eur Neuropsychopharmacol 2005; 15:587-90. [PMID: 16139176 DOI: 10.1016/j.euroneuro.2005.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2004] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Prepulse inhibition of acoustic startle is a behavioural response, which is used to estimate sensorimotor gating deficits in schizophrenia. Recent studies show that several behavioural effects of the psychotomimetic drug, phencyclidine (PCP), in rodents are blocked by nitric oxide synthase (NOS) inhibitors suggesting that NO plays an important role in the pharmacological effects of PCP. The present study was conducted to examine the effects of PCP on prepulse inhibition in neuronal NOS (nNOS) deficient mice. PCP treatment caused a significant and dose-related increase in prepulse inhibition in nNOS-/- mice whereas prepulse inhibition was not significantly affected in +/+ and +/- mice. Basal prepulse inhibition level did not differ significantly between the groups. Furthermore, PCP caused a dose-related decrease in startle response reactivity in +/+ mice but did not significantly affect this measure in +/- and -/- mice. Basal startle response level did not differ between +/+ and +/- but was significantly lower in -/- mice. It is concluded that nNOS plays a role in the NO-sensitive effects of PCP.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy at Göteborg University, POB 431, SE 405 30 Göteborg, Sweden
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Klamer D, Pålsson E, Wass C, Archer T, Engel JA, Svensson L. Antagonism of the nitric oxide synthase inhibitor, L-NAME, of the effects of phencyclidine on latent inhibition in taste aversion conditioning. Behav Brain Res 2005; 161:60-8. [PMID: 15904710 DOI: 10.1016/j.bbr.2005.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Accepted: 01/12/2005] [Indexed: 11/21/2022]
Abstract
Latent inhibition (LI) is a behavioural procedure used to evaluate the potential propsychotic and antipsychotic properties of psychoactive drugs. In the present study, a conditioned taste aversion (CTA) procedure was used to investigate the effects of the nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), and the psychotomimetic drugs, phencyclidine (PCP) and d-amphetamine (d-AMP) on LI. PCP (2 mg/kg) and d-AMP (0.5 mg/kg) were both found to enhance LI in this procedure. The effect of d-AMP on LI was less pronounced and this drug also caused a weak disruption of taste aversion conditioning. Pretreatment with L-NAME (10 mg/kg) blocked the LI enhancing effect of PCP on LI but not that of d-AMP. L-NAME by itself caused an attenuation of LI. L-NAME has been shown to block also other behavioural and biochemical effects of PCP in previous studies and these results and the present findings suggest that at least some of the effects PCP are dependent on NO and possibly also that some NOS inhibitors may exert antipsychotic properties.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy at Göteborg University, Göteborg University, P.O.B. 431, SE 405-30 Göteborg, Sweden
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Klamer D, Pålsson E, Fejgin K, Zhang J, Engel JA, Svensson L. Activation of a nitric-oxide-sensitive cAMP pathway with phencyclidine: elevated hippocampal cAMP levels are temporally associated with deficits in prepulse inhibition. Psychopharmacology (Berl) 2005; 179:479-88. [PMID: 15619121 DOI: 10.1007/s00213-004-2051-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Accepted: 09/24/2004] [Indexed: 12/22/2022]
Abstract
RATIONALE Schizophrenic patients show deficits in pre-attentive information processing as evidenced, for example, by disrupted prepulse inhibition, a measure of sensorimotor gating. A similar disruption can be observed in animals treated with the psychotomimetic agent, phencyclidine (PCP). However, the mechanism by which PCP alters brain function has not been fully elucidated. Recent studies have demonstrated that certain behavioural and neurochemical effects of PCP in rats and mice are blocked by nitric oxide (NO) synthase inhibition, suggesting an important role for NO in the effects of PCP. OBJECTIVE The aim of the present study was to investigate the effects of PCP on cAMP production in the ventral hippocampus and the role of NO in these effects using in vivo microdialysis in rats. Furthermore, the effects of PCP on acoustic startle reactivity and prepulse inhibition of acoustic startle were compared with changes in cAMP levels in the ventral hippocampus. RESULTS Significant increases in cAMP levels were observed in the ventral hippocampus following both local infusion (10(-4) mol/l and 10(-3) mol/l) and systemic administration (2 mg/kg) of PCP. The PCP-induced changes in prepulse inhibition and startle reactivity were associated in magnitude and duration with the increase in cAMP levels in the hippocampus. Furthermore, systemic administration of the NO synthase inhibitor, L: -NAME (10 mg/kg), blocked both the changes in cAMP levels and the behavioural responses induced by PCP. CONCLUSIONS These findings indicate that the effects of PCP on prepulse inhibition and startle reactivity are associated with an increase in cAMP levels in the ventral hippocampus, and that this change in cAMP response may be linked to the production of NO.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy, Göteborg University, POB 431, SE 405 30 Goteborg, Sweden
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Klamer D, Engel JA, Svensson L. The neuronal selective nitric oxide synthase inhibitor, Nomega-propyl-L-arginine, blocks the effects of phencyclidine on prepulse inhibition and locomotor activity in mice. Eur J Pharmacol 2005; 503:103-7. [PMID: 15496304 DOI: 10.1016/j.ejphar.2004.09.042] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2004] [Accepted: 09/10/2004] [Indexed: 11/28/2022]
Abstract
Phencyclidine has frequently been used to model schizophrenia in animals. In the present study, the ability of the neuronal selective nitric oxide synthase (NOS) inhibitor, Nomega-propyl-L-arginine, to block the behavioural effects of phencyclidine in mice was investigated. N(omega)-propyl-L-arginine (20 mg/kg) was found to block both phencyclidine (4 mg/kg)-induced disruption of prepulse inhibition and phencyclidine-induced stimulation of locomotor activity in the mice tested. It is concluded that the NOS-sensitive behavioural effects of phencyclidine in rodents is dependent on neuronal NOS and that NO may play a role in the psychotomimetic effects of phencyclidine.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy at Göteborg University, POB 431, SE 405 30 Göteborg, Sweden
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Klamer D, Zhang J, Engel JA, Svensson L. Selective interaction of nitric oxide synthase inhibition with phencyclidine: behavioural and NMDA receptor binding studies in the rat. Behav Brain Res 2005; 159:95-103. [PMID: 15795002 DOI: 10.1016/j.bbr.2004.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 10/11/2004] [Accepted: 10/13/2004] [Indexed: 12/26/2022]
Abstract
The psychotomimetic drugs, phencyclidine (PCP) and MK-801, are non-competitive antagonists of the N-methyl-d-aspartate (NMDA) receptor and used as pharmacological tools to mimic a possible NMDA receptor hypofunction in schizophrenia. These drugs were tested in two behavioural paradigms in the present study: prepulse inhibition (PPI) of acoustic startle and locomotor activity (LMA) in an open field. Recent studies show that several behavioural and biochemical effects of PCP are blocked by nitric oxide synthase (NOS) inhibition. Hence, it is likely that some effects of PCP are mediated via an increase in NO production, an assumption not in accordance with the NMDA receptor antagonistic effect of PCP. Experiments were conducted in rats to further elucidate the involvement of NO-dependent mechanisms in the effects of PCP and MK-801, and how these effects may involve the NMDA receptor. The NOS inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME) (10 mg/kg) normalised the disruptive effect of PCP (2 mg/kg) on PPI and the stimulatory effect of PCP (4 mg/kg) on LMA. In contrast to these observations, the deficit in PPI induced by MK-801 (0.1 mg/kg) was not affected by L-NAME (10, 20 or 40 mg/kg). MK-801 (0.15 mg/kg)-induced hyperlocomotion was not affected by L-NAME (10 mg/kg), but attenuated by L-NAME (40 mg/kg). Furthermore, receptor binding studies aimed at investigating the influence of L-NAME on the binding of PCP to the MK-801-sensitive NMDA receptor binding site failed to show such an influence. These results suggest that the NO-sensitive effects of PCP are not sufficiently explained by its antagonistic effect at the NMDA receptor channel complex.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy at Göteborg University, Göteborg University, P.O. Box 431, SE 40530 Göteborg, Sweden
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Klamer D, Pålsson E, Revesz A, Engel JA, Svensson L. Habituation of acoustic startle is disrupted by psychotomimetic drugs: differential dependence on dopaminergic and nitric oxide modulatory mechanisms. Psychopharmacology (Berl) 2004; 176:440-50. [PMID: 15173930 DOI: 10.1007/s00213-004-1901-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Accepted: 03/29/2004] [Indexed: 10/26/2022]
Abstract
RATIONALE A deficit in attention and information processing has been considered a central feature in schizophrenia, which might lead to stimulus overload and cognitive fragmentation. It has been shown that patients with schizophrenia display a relative inability to gate incoming stimuli. Thus, patients repeatedly subjected to acoustic startle-eliciting stimuli habituate less to these stimuli than controls. Furthermore, schizophrenia-like symptoms can be induced by pharmacological manipulations in humans by psychotomimetic drugs, e.g. phencyclidine (PCP) and D-amphetamine (D-AMP). Recent studies show that the behavioural and biochemical effects of PCP in rodents are blocked by nitric oxide synthase (NOS) inhibitors, suggesting that NO plays an important role in at least the pharmacological effects of PCP. OBJECTIVES The first aim of the present study was to investigate if PCP, MK-801 and D-AMP impair habituation of acoustic startle in mice. Secondly, we examine the effect of the NOS inhibitor, L-NAME, and the dopamine receptor antagonist, haloperidol, on drug-induced deficit in habituation. RESULTS PCP (4 mg/kg), MK-801 (0.4 mg/kg) and D-AMP (5.0 mg/kg), impaired habituation of the acoustic startle response in mice. This effect was reversed by the NOS inhibitor, L-NAME. The typical antipsychotic, haloperidol, reversed the effects of PCP and D-AMP, but not that of MK-801. CONCLUSIONS The finding that PCP, MK-801 and D-AMP impair habituation in mice is consistent with the idea that these treatments model certain filter deficits seen in schizophrenic patients. Furthermore, the present results suggest that NO is critically involved in these effects on habituation, whereas that of dopamine is less clear.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, The Sahlgrenska Academy, Göteborg University, PO Box 431, 405-30, Goteborg, Sweden
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Ukai M, Okuda A, Mamiya T. Effects of anticholinergic drugs selective for muscarinic receptor subtypes on prepulse inhibition in mice. Eur J Pharmacol 2004; 492:183-7. [PMID: 15178363 DOI: 10.1016/j.ejphar.2004.03.066] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Revised: 03/11/2004] [Accepted: 03/25/2004] [Indexed: 11/17/2022]
Abstract
The effects of anticholinergic drugs selective for muscarinic receptor subtypes on prepulse inhibition of acoustic startle response were determined in mice. The prepulse inhibition is associated with sensorimotor information processing in the brain. The anticholinergic agent scopolamine (0.3 mg/kg, s.c.) significantly attenuated prepulse inhibition, while the drug (1-10 mg/kg, s.c.) had no effects on startle amplitude as an indicator of startle response. The muscarinic M(1) receptor antagonist pirenzepine (0.1-10 microg/mouse, i.c.v.) and the muscarinic M(2) receptor antagonist AF-DX116 (11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one) (0.1-10 microg/mouse, i.c.v.) had no effects on prepulse inhibition or startle amplitude. The muscarinic M(3) receptor antagonist 4-DAMP (1,1-dimethyl-4-diphenylacetoxy-piperidinium iodide) (30 microg/mouse, i.c.v.) and the muscarinic M(4) receptor antagonist tropicamide (0.1 microg/mouse, i.c.v.) significantly attenuated prepulse inhibition, while tropicamide (0.01 microg/mouse, i.c.v.) but not 4-DAMP (10 and 30 microg/mouse, i.c.v.) produced a significant increase in startle amplitude. These results suggest that the blockade of muscarinic M(3) and M(4) receptors leads to the disruption of prepulse inhibition.
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MESH Headings
- Animals
- Cholinergic Antagonists/pharmacology
- Injections, Intraventricular
- Male
- Mice
- Muscarinic Antagonists/pharmacology
- Piperidines/pharmacology
- Pirenzepine/analogs & derivatives
- Pirenzepine/pharmacology
- Receptor, Muscarinic M1/antagonists & inhibitors
- Receptor, Muscarinic M1/physiology
- Receptor, Muscarinic M2/antagonists & inhibitors
- Receptor, Muscarinic M2/physiology
- Receptor, Muscarinic M3/antagonists & inhibitors
- Receptor, Muscarinic M3/physiology
- Receptor, Muscarinic M4/antagonists & inhibitors
- Receptor, Muscarinic M4/physiology
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/physiology
- Reflex, Startle/drug effects
- Reflex, Startle/physiology
- Scopolamine/pharmacology
- Tropicamide/pharmacology
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Affiliation(s)
- Makoto Ukai
- Department of Chemical Pharmacology, Faculty of Pharmacy, Meijo University, Nagoya 468-8503, Japan.
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Klamer D, Engel JA, Svensson L. Phencyclidine-induced behaviour in mice prevented by methylene blue. Basic Clin Pharmacol Toxicol 2004; 94:65-72. [PMID: 14748849 DOI: 10.1111/j.1742-7843.2004.pto940203.x] [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] [Indexed: 11/26/2022]
Abstract
Schizophrenia is a major public health problem that affects approximately 1% of the population worldwide. Schizophrenia-like symptoms can be induced in humans by phencyclidine (PCP), a drug with marked psychotomimetic properties. Phencyclidine disrupts prepulse inhibition of acoustic startle in rodents, a measure which has also been shown to be disrupted in schizophrenic patients. This effect is blocked by nitric oxide synthase (NOS) inhibitors, suggesting that nitric oxide plays an important role in this effect of phencyclidine. Methylene blue, a guanylate cyclase and nitric oxide syntase inhibitor, has shown therapeutic value as an adjuvant to conventional antipsychotics in the therapy of schizophrenia. The aim of the present study was to investigate if phencyclidine-(4 mg/kg)induced disruption of prepulse inhibition could be affected by methylene blue (50 or 100 mg/kg) in mice. Furthermore, the effect of methylene blue (50 mg/kg) on phencyclidine-(4 mg/kg)induced hyperlocomotion was investigated. The present study shows that phencyclidine readily disrupts prepulse inhibition in mice without affecting pulse-alone trials. It was also found that methylene blue prevents the decrease in prepulse inhibition caused by phencyclidine in a dose-related manner. Furthermore, the increase in locomotor activity caused by phencyclidine was reduced by pretreatment with methylene blue. The results from the present study further support the suggestion that the nitric oxide synthase/guanylate cyclase pathway is involved in pharmacological and behavioural effects of phencyclidine. Since phencyclidine as well exerts psychotomimetic characteristics, agents that interfere with the nitric oxide synthase/guanylate cyclase pathway may be of therapeutic value also in the treatment of schizophrenia.
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Affiliation(s)
- Daniel Klamer
- Department of Pharmacology, Göteborg University, Göteborg, Sweden
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Geyer MA, McIlwain KL, Paylor R. Mouse genetic models for prepulse inhibition: an early review. Mol Psychiatry 2003; 7:1039-53. [PMID: 12476318 DOI: 10.1038/sj.mp.4001159] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2002] [Revised: 03/08/2002] [Accepted: 03/15/2002] [Indexed: 11/10/2022]
Abstract
Prepulse inhibition (PPI) is the phenomenon in which a weak prepulse stimulus attenuates the response to a subsequent startling stimulus. Patients with schizophrenia and some other neuropsychiatric disorders have impaired PPI. Impaired PPI in these patient populations is thought to reflect dysfunctional sensorimotor gating mechanisms. Recently, various inbred mouse strains and genetically modified mouse lines have been examined to investigate the potential genetic basis of sensorimotor gating. This review provides a synopsis of the use of mouse models to explore genetic and neurochemical influences on PPI. Studies describing the PPI responses of various inbred strains of mice, mice with genetic mutations, and mice treated with various drugs prior to July 2001 are reviewed. The continuous nature of the distribution of PPI responses among inbred strains of mice indicates that PPI is a polygenic trait. Findings from spontaneous and gene-targeted mutants suggest that mutant mice are important tools for dissecting and studying the role of single genes and their products, and chromosomal regions in regulating PPI. Pharmacological studies of PPI have typically confirmed effects in mice that are similar to those reported previously in rats, with some important exceptions. The use of mice to study PPI is increasing at a dramatic rate and is helping to increase our understanding of the biological basis for sensorimotor gating.
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Affiliation(s)
- M A Geyer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, USA
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Suzuki E, Nakaki T, Shintani F, Kanba S, Miyaoka H. Antipsychotic, antidepressant, anxiolytic, and anticonvulsant drugs induce type II nitric oxide synthase mRNA in rat brain. Neurosci Lett 2002; 333:217-9. [PMID: 12429386 DOI: 10.1016/s0304-3940(02)01035-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Nitric oxide synthase inhibitors have been regarded as potentially beneficial for psychiatric disorders such as depression and schizophrenia, though little is known about how nitric oxide synthases are affected by psychotropic drugs in the brain. Using reverse transcription-polymerase chain reaction analysis, we investigated the effects of short- and long-term oral treatments with several psychotropics on type II nitric oxide synthase gene expression in the rat brain. With maprotiline and fluvoxamine, enzyme mRNA levels were higher after a 28 day treatment than after 1 and 4 day treatments. Zonisamide, carbamazepine and diazepam also increased mRNA, though differences in levels between 1, 4 and 28 day treatments were not significant. These results suggest that psychotropics modulate the gene expression of type-II nitric oxide synthase in the brain.
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Affiliation(s)
- Eiji Suzuki
- Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Sagamihara, Kanagawa 228-8520, Japan.
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