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Ross AJ, Sherriff A, Kidd J, Deas L, Eaves J, Blokland A, Wright B, King P, McMahon AD, Conway DI, Macpherson LMD. Evaluating childsmile, Scotland's National Oral Health Improvement Programme for children. Community Dent Oral Epidemiol 2023; 51:133-138. [PMID: 36753390 DOI: 10.1111/cdoe.12790] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 06/08/2022] [Accepted: 08/15/2022] [Indexed: 02/09/2023]
Abstract
In the early 2000s, a Scottish Government Oral Health Action Plan identified the need for a national programme to improve child oral health and reduce inequalities. 'Childsmile' aimed to improve child oral health in Scotland, reduce inequalities in outcomes and access to dental services, and to shift the balance of care from treatment to prevention through targeted and universal components in dental practice, community and educational settings. This paper describes how an embedded, theory-based research and evaluation arm with multi-disciplinary input helps determine priorities and provides important strategic direction. Programme theory is articulated in dedicated, dynamic logic models, and evaluation themes are as follows: population-level data linkage; trials and economic evaluations; investigations drawing from behavioural and implementation science; evidence reviews and updates; and applications of systems science. There is also a growing knowledge sharing network internationally. Collaborative working from all stakeholders is necessary to maintain gains and to address areas that may not be working as well, and never more so with the major disruptions to the programme from the COVID-19 pandemic and response. Conclusions are that evaluation and research are synergistic with a complex, dynamic programme like Childsmile. The evidence obtained allows for appraisal of the relative strengths of component interventions and the reach and impact of Childsmile to feed into national policy.
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Affiliation(s)
- Alastair J Ross
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrea Sherriff
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Jamie Kidd
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Leigh Deas
- Public Dental Service, NHS Lanarkshire, Glasgow, UK
| | - Jenny Eaves
- Public Dental Service, NHS Lanarkshire, Glasgow, UK
| | - Alex Blokland
- Department of Epidemiology and Public Health, University College London, London, UK
| | - Bill Wright
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Peter King
- Public Dental Service, NHS Lanarkshire, Glasgow, UK
| | - Alex D McMahon
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - David I Conway
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Lorna M D Macpherson
- Community Oral Health Group, University of Glasgow Dental School, School of Medicine, Dentistry & Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
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Abstract
BACKGROUND There are stark ethnic inequalities in the prevalence of UK childhood obesity. However, data on adolescent overweight in different ethnic groups are limited. This study assessed ethnic inequalities in overweight prevalence during mid-adolescence using body mass index (BMI) and explored the contribution of socioeconomic and behavioural factors. METHODS We analyzed data from 10 500 adolescents aged between 13 and 15 years who participated in sweep six of the Millennium Cohort Study. Ethnic inequalities in overweight and mean BMI were assessed using multiple regression models. Results were stratified by sex and adjusted for socioeconomic and behavioural factors. RESULTS Black Caribbean males had significantly higher BMI than White males after full adjustment [excess BMI 2.94, 95% confidence interval (CI) 0.70-5.19] and were over three times more likely to be overweight [odds ratio (OR): 3.32, 95% CI 1.95-5.66]. Black Africans females had significantly higher BMI compared with White females (excess BMI 1.86, 95% CI 0.89-2.83; OR for overweight 2.74, 95% CI 1.64-4.56), while Indian females had significantly lower BMI compared with White females (reduced BMI -0.73, 95% CI -1.37 to -0.09). Socioeconomic and behavioural factors often considered to be associated with overweight were more prevalent in some ethnic minority groups (lower socioeconomic position, lack of breakfast consumption, low fruit and vegetable intake, high sugar-sweetened beverage and fast-food consumption, and infrequent physical activity), but adjustment for these factors did not fully explain ethnic differences in overweight/BMI. CONCLUSION Ethnic inequalities in overweight prevalence are evident in mid-adolescence and vary according to sex. Differences in overweight/BMI between ethnic groups were not fully accounted for by socioeconomic or behavioural factors.
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Affiliation(s)
- Michelle Stennett
- Department of Epidemiology and Public Health,
University College London, London, UK
| | - Alex Blokland
- Department of Epidemiology and Public Health,
University College London, London, UK
| | - Richard G Watt
- Department of Epidemiology and Public Health,
University College London, London, UK
| | - Anja Heilmann
- Department of Epidemiology and Public Health,
University College London, London, UK
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Venturelli R, Blokland A, de Oliveira C, Machuca C, Watt RG. Oral health and depressive symptoms: findings from the English Longitudinal Study of Ageing. Br Dent J 2021:10.1038/s41415-021-2603-1. [PMID: 33574578 DOI: 10.1038/s41415-021-2603-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 06/23/2020] [Indexed: 11/09/2022]
Abstract
Aim We assessed the cross-sectional association between depressive symptoms and oral health using a nationally representative sample of older adults aged 50 years and older living in England.Methods Data came from wave 7 (2014-2015) of the English Longitudinal Study of Ageing. Multiple logistic regression analyses were conducted to assess the association between depressive symptoms, measured through the eight-item Centre for Epidemiologic Studies Depression Scale and three oral health outcomes, namely self-rated oral health, edentulousness and oral impacts.Results The analytical sample comprised 3,617 individuals. The proportion of participants that reported poor self-rated oral health, being edentate and having at least one oral health impact in the last six months was 19.8%, 7.7% and 8.9%, respectively. Around a tenth of the participants reported having depressive symptoms (10%). All unadjusted associations between depressive symptoms and the oral health measures were statistically significant. However, after accounting for potential confounders, only the relationship between depressive symptoms and self-rated oral health remained significant (OR = 1.38; 95% CI 1.01-1.89). Socioeconomic and general health-related variables appeared to influence the associations between depressive symptoms and oral health, particularly edentulousness and oral impacts.Conclusion Depressive symptoms were associated with poor self-rated oral health in older English adults.
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Affiliation(s)
- Renato Venturelli
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, WC1E 6BT, London, UK.
| | - Alex Blokland
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, WC1E 6BT, London, UK
| | - Cesar de Oliveira
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, WC1E 6BT, London, UK
| | - Carolina Machuca
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, WC1E 6BT, London, UK
| | - Richard G Watt
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, WC1E 6BT, London, UK
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Koh J, Lim W, Neoh J, Hescham S, Blokland A, Chan Y, Temel Y, Lim L, Wu E. Pacemaker in the aged brain: From molecular profiling to memory enhancement. Brain Stimul 2019. [DOI: 10.1016/j.brs.2018.12.412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Abstract
BACKGROUND Animal literature suggests an interaction between acetylcholine and serotonin on cognitive functions. AIMS The aim of the current study was to assess whether both neurotransmitters interact during memory and novelty processing in humans. METHODS We tested the interaction between acetylcholine and serotonin on cognitive functions in healthy volunteers by means of treatment with rivastigmine and citalopram, respectively. RESULTS The main result of the study showed that during the verbal learning task participants significantly recalled fewer words after citalopram treatment than after rivastigmine or placebo during both the immediate and delayed recall tasks. Rivastigmine was not able to reverse the impairing effect of citalopram. CONCLUSIONS This finding is in line with previous studies in which we manipulated acetylcholine and serotonin in different manners. Taken together, these studies in humans do not support the notion from animal studies that these two neurotransmitters interact on cognitive functions.
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Affiliation(s)
- Pra Heckman
- 1 Department of Neuropsychology and Psychopharmacology, Maastricht University, The Netherlands.,2 Department of Psychiatry and Neuropsychology, Maastricht University, The Netherlands
| | - A Blokland
- 1 Department of Neuropsychology and Psychopharmacology, Maastricht University, The Netherlands
| | - A Sambeth
- 1 Department of Neuropsychology and Psychopharmacology, Maastricht University, The Netherlands
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Caldenhove S, Sambeth A, Sharma S, Woo G, Blokland A. Correction to: A Combination of Nootropic Ingredients (CAF+) Is Not Better than Caffeine in Improving Cognitive Functions. J Cogn Enhanc 2018. [DOI: 10.1007/s41465-018-0071-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Heckman PRA, Blokland A, Van Goethem NP, Van Hagen BTJ, Prickaerts J. The mediating role of phosphodiesterase type 4 in the dopaminergic modulation of motor impulsivity. Behav Brain Res 2018; 350:16-22. [PMID: 29778625 DOI: 10.1016/j.bbr.2018.05.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/26/2018] [Accepted: 05/15/2018] [Indexed: 01/16/2023]
Abstract
The current study investigated the mediating role of phosphodiesterase type 4 (PDE4) regulated cAMP in the dopaminergic modulation of premature responding (action restraint) in rats. Response inhibition, which includes action restraint, finds its neurobiological origin in cortico-striatal-thalamic circuitry and can be modulated by dopamine. Intracellularly, the effect of dopamine is largely mediated through the cAMP/PKA signaling cascade. Areas in the prefrontal cortex are very sensitive to their neurochemical environment, including catecholamine levels. As a result, we investigated the effects of intracellular modulation of the dopamine cascade by means of PDE4 inhibition by roflumilast on premature responding in a hypo, normal and hyper dopaminergic state of the brain. As a hypo dopaminergic model we induced a 6-OHDA lesion in the (rat) prefrontal cortex, more specifically the infralimbic cortex. For the hyper dopaminergic state we also turned to a well-established model of impaired action restraint, namely the systemic administration of d-amphetamine. In line with the notion of a U-shaped relation between dopamine and impulsive responding, we found that both increasing and decreasing dopamine levels resulted in an increase in premature responding in the choice serial reaction time task (CSRTT). The PDE4 inhibitor roflumilast increased premature responses in combination with d-amphetamine, whereas a decrease in premature responding after roflumilast treatment was found in the 6-OHDA lesioned animals. As a result, it would be interesting to test the effects of PDE4 inhibition in disorders affected by disrupted impulse control related to cortico-striatal-thalamic hypodopaminergia including attention deficit hyperactivity disorder (ADHD).
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Affiliation(s)
- P R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands; Department of Neuropsychology and Psychopharmacology, Maastricht University, 6200 MD Maastricht, The Netherlands.
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - N P Van Goethem
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - B T J Van Hagen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands
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Blokland A. Meet Our Editorial Board Member. Curr Neuropharmacol 2018. [DOI: 10.2174/1570159x1604180501124304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- A. Blokland
- Maastricht University Maastricht, Netherlands
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9
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Heckman PRA, Blokland A, Bollen EPP, Prickaerts J. Phosphodiesterase inhibition and modulation of corticostriatal and hippocampal circuits: Clinical overview and translational considerations. Neurosci Biobehav Rev 2018; 87:233-254. [PMID: 29454746 DOI: 10.1016/j.neubiorev.2018.02.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 02/07/2018] [Accepted: 02/09/2018] [Indexed: 12/20/2022]
Abstract
The corticostriatal and hippocampal circuits contribute to the neurobiological underpinnings of several neuropsychiatric disorders, including Alzheimer's disease, Parkinson's disease and schizophrenia. Based on biological function, these circuits can be clustered into motor circuits, associative/cognitive circuits and limbic circuits. Together, dysfunctions in these circuits produce the wide range of symptoms observed in related neuropsychiatric disorders. Intracellular signaling in these circuits is largely mediated through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway with an additional role for the cyclic guanosine monophosphate (cGMP)/ protein kinase G (PKG) pathway, both of which can be regulated by phosphodiesterase inhibitors (PDE inhibitors). Through their effects on cAMP response element-binding protein (CREB) and Dopamine- and cAMP-Regulated PhosphoProtein MR 32 kDa (DARPP-32), cyclic nucleotide pathways are involved in synaptic transmission, neuron excitability, neuroplasticity and neuroprotection. In this clinical review, we provide an overview of the current clinical status, discuss the general mechanism of action of PDE inhibitors in relation to the corticostriatal and hippocampal circuits and consider several translational challenges.
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Affiliation(s)
- P R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands.
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - E P P Bollen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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Caldenhove S, Sambeth A, Sharma S, Woo G, Blokland A. A Combination of Nootropic Ingredients (CAF+) Is Not Better than Caffeine in Improving Cognitive Functions. J Cogn Enhanc 2017. [DOI: 10.1007/s41465-017-0061-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Caldenhove S, Borghans L, Blokland A, Sambeth A. Role of acetylcholine and serotonin in novelty processing using an oddball paradigm. Behav Brain Res 2017; 331:199-204. [DOI: 10.1016/j.bbr.2017.05.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 12/28/2022]
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Blokland A, Watt RG, Tsakos G, Heilmann A. Traumatic dental injuries and socioeconomic position - findings from the Children's Dental Health Survey 2013. Community Dent Oral Epidemiol 2016; 44:586-591. [DOI: 10.1111/cdoe.12252] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/19/2016] [Indexed: 11/25/2022]
Affiliation(s)
- Alex Blokland
- Department of Epidemiology and Public Health; University College London; London UK
| | - Richard G. Watt
- Department of Epidemiology and Public Health; University College London; London UK
| | - Georgios Tsakos
- Department of Epidemiology and Public Health; University College London; London UK
| | - Anja Heilmann
- Department of Epidemiology and Public Health; University College London; London UK
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Akkerman S, Blokland A, van Goethem NP, Cremers P, Shaffer CL, Osgood SM, Steinbusch HWM, Prickaerts J. PDE5 inhibition improves acquisition processes after learning via a central mechanism. Neuropharmacology 2015; 97:233-9. [PMID: 26027948 DOI: 10.1016/j.neuropharm.2015.04.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 04/11/2015] [Accepted: 04/18/2015] [Indexed: 10/23/2022]
Abstract
In previous studies, we have shown that phosphodiesterase type 5 inhibitors (PDE5-Is) can improve early consolidation of object memory. These conclusions were based on the timing of drug administration relative to the learning trial (i.e. before or after). However, there are very little pharmacological data available about the pharmacokinetic profile of orally administered PDE5-Is in the rat. Furthermore, there is still debate whether these effects are achieved via central or peripheral mechanisms and if acquisition processes are improved. In the current study, we tested the effects of the PDE5-I vardenafil in a cholinergic-deficit model and compared the effects after intracerebroventricular (ICV) versus oral (PO) administration. We found that PO vardenafil restored a scopolamine-induced memory impairment when dosed within 2 min after the learning trial while ICV vardenafil was able to restore memory when injected within 4 min after learning. Because the test trial was within 10 min after the learning trial, this suggests that these effects on object memory are related to acquisition processes that may still be ongoing in a time window after the learning trial. To further elucidate the extent of this acquisition window, we investigated the pharmacokinetic profile of vardenafil after PO administration where it was detected within 4 min post-dose. Taken together, our data suggest that PDE5 is involved in acquisition processes, which may linger for at least 4-6 min after learning. Further studies are needed to exclude that these effects could also be explained on basis of an effect on early consolidation processes. Additionally, the effectiveness of ICV-administered vardenafil provides further experimental evidence that PDE5-Is improve memory via a central mechanism.
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Affiliation(s)
- S Akkerman
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - N P van Goethem
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - P Cremers
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - C L Shaffer
- Department of Pharmacokinetics, Pharmacodynamics and Metabolism, Worldwide Research & Development, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - S M Osgood
- Department of Pharmacokinetics, Pharmacodynamics and Metabolism, Worldwide Research & Development, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA
| | - H W M Steinbusch
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands.
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Bollen E, Akkerman S, Puzzo D, Gulisano W, Palmeri A, D'Hooge R, Balschun D, Steinbusch HWM, Blokland A, Prickaerts J. Object memory enhancement by combining sub-efficacious doses of specific phosphodiesterase inhibitors. Neuropharmacology 2015; 95:361-6. [PMID: 25896769 DOI: 10.1016/j.neuropharm.2015.04.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 02/13/2015] [Accepted: 04/03/2015] [Indexed: 01/17/2023]
Abstract
The second messengers cGMP and cAMP have a vital role in synaptic plasticity and memory processes. As such, phosphodiesterases inhibitors (PDE-Is), which prevent the breakdown of these cyclic nucleotides, represent a potential treatment strategy in memory decline. Recently it has been demonstrated that cGMP and cAMP signaling act in sequence during memory consolidation, with early cGMP signaling requiring subsequent cAMP signaling. Here, we sought to confirm this relationship, and to evaluate its therapeutic implications. Combining sub-efficacious doses of the cGMP-specific PDE type 5 inhibitor vardenafil (0.1 mg/kg) and cAMP-specific PDE type 4 inhibitor rolipram (0.01 mg/kg) during the early and late memory consolidation phase, respectively, led to improved memory performance in a 24 h interval object recognition task. Similarly, such a sub-efficacious combination treatment enhanced the transition of early-phase long-term potentiation (LTP) to late-phase LTP in hippocampal slices. In addition, both object memory and LTP were improved after administration of two sub-efficacious doses of the dual substrate PDE type 2 inhibitor BAY60 7550 (0.3 mg/kg) at the early and late consolidation phase, respectively. Taken together, combinations of sub-efficacious doses of cAMP- and cGMP-specific PDE-Is have an additive effect on long-term synaptic plasticity and memory formation and might prove a superior alternative to single PDE-I treatment.
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Affiliation(s)
- E Bollen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - S Akkerman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - D Puzzo
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - W Gulisano
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - A Palmeri
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - R D'Hooge
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - D Balschun
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - H W M Steinbusch
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Heckman PRA, Blokland A, Ramaekers J, Prickaerts J. PDE and cognitive processing: beyond the memory domain. Neurobiol Learn Mem 2014; 119:108-22. [PMID: 25464010 DOI: 10.1016/j.nlm.2014.10.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/29/2014] [Accepted: 10/30/2014] [Indexed: 01/01/2023]
Abstract
Phosphodiesterase inhibitors (PDE-Is) enhance cAMP and/or cGMP signaling via reducing the degradation of these cyclic nucleotides. Both cAMP and cGMP signaling are essential for a variety of cellular functions and exert their effects both pre- and post-synaptically. Either of these second messengers relays and amplifies incoming signals at receptors on the cell surface making them important elements in signal transduction cascades and essential in cellular signaling in a variety of cell functions including neurotransmitter release and neuroprotection. Consequently, these processes can be influenced by PDE-Is as they increase cAMP and/or cGMP concentrations. PDE-Is have been considered as possible therapeutic agents to treat impaired memory function linked to several brain disorders, including depression, schizophrenia and Alzheimer's disease (AD). This review will, however, focus on the possible role of phosphodiesterases (PDEs) in cognitive decline beyond the memory domain. Here we will discuss the involvement of PDEs on three related domains: attention, information filtering (sensory- and sensorimotor gating) and response inhibition (drug-induced hyperlocomotion). Currently, these are emerging cognitive domains in the field of PDE research. Here we discuss experimental studies and the potential beneficial effects of PDE-I drugs on these cognitive domains, as effects of PDE-Is on these domains could potentially influence effects on memory performance. Overall, PDE4 seems to be the most promising target for all domains discussed in this review.
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Affiliation(s)
- P R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands; Department of Neuropsychology and Psychopharmacology, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - J Ramaekers
- Department of Neuropsychology and Psychopharmacology, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands.
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van Donkelaar EL, Prickaerts J, Akkerman S, Rutten K, Steinbusch HWM, Blokland A. No effect of acute tryptophan depletion on phosphodiesterase inhibition--related improvements of short-term object memory in male Wistar rats. Acta Psychiatr Scand 2013; 128:107-13. [PMID: 23772681 DOI: 10.1111/acps.12166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/16/2013] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To further explore the implication of the serotonin (5-HT) system in the improvement of rat short-term object recognition after administration of the type 2 phosphodiesterase inhibitor (PDE-I) BAY 60-7550 and the type 5 PDE-I vardenafil, the effect of PDE2 and PDE5 inhibition upon central amino acid levels, 5-HT, and related parameters were measured after applying acute tryptophan depletion (ATD). METHOD Wistar rats were orally administered saline or a protein-carbohydrate mixture with or without tryptophan (TRP). TRP-depleted animals additionally received an oral vehicle injection or the PDE inhibitors BAY 60-7550 or vardenafil at a dose known to improve object memory performance. RESULTS Although ATD significantly decreased TRP levels in the hippocampus 2 h after administration, 5-HT levels appeared only moderately affected, without any changes observed in the amount of 5-HIAA or 5-HT turnover rate. Moreover, no effects of PDE inhibition upon 5-HT or related parameters were observed. CONCLUSION Changes in 5-HT neurotransmitter activity might be excluded as a potential underlying mechanism of the previously reported ability of PDE inhibitors to improve short-term object memory in rats. It is suggested that a decrease in cerebral blood flow potentially underlies ATD-induced object memory deficits, most likely due to decrease in NO synthesis.
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Affiliation(s)
- E L van Donkelaar
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
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Reneerkens OAH, Sambeth A, Ramaekers JG, Steinbusch HWM, Blokland A, Prickaerts J. The effects of the phosphodiesterase type 5 inhibitor vardenafil on cognitive performance in healthy adults: a behavioral-electroencephalography study. J Psychopharmacol 2013; 27:600-8. [PMID: 23427190 DOI: 10.1177/0269881113477747] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Phosphodiesterase type 5 inhibitors (PDE5-Is) improve cognitive performance of rodents, but the few human studies investigating their effects did not systematically investigate cognitive effects and the results have been quite contradictory. Therefore, we examined whether the PDE5-I vardenafil improves memory and executive functioning and affect electroencephalography (EEG) in healthy young adults. Participants were selected out of a group of volunteers, based on their performance on a memory screening and they were orally treated with vardenafil (10-20 mg or placebo). Memory and executive functioning were tested while EEG activity was recorded. Additionally, a simple reaction time task and questionnaires addressing various complaints were presented. No prominent effects of vardenafil on cognition were found: participants only made more mistakes on a reaction time task after 20 mg vardenafil. During encoding of words, the P300 was generally smaller after vardenafil treatment. Furthermore, the N400 was larger after vardenafil 10 mg than placebo treatment in a spatial memory task at Fz. Finally, headache and feeling weak were reported more after vardenafil treatment. Vardenafil did not affect cognitive performance of healthy adults and showed only some incidental effects on ERPs. These findings in humans do not corroborate the cognition-enhancing effects of PDE5-Is in healthy animals.
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Affiliation(s)
- O A H Reneerkens
- Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, the Netherlands
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Reneerkens OAH, Sambeth A, Van Duinen MA, Blokland A, Steinbusch HWM, Prickaerts J. The PDE5 inhibitor vardenafil does not affect auditory sensory gating in rats and humans. Psychopharmacology (Berl) 2013; 225:303-12. [PMID: 22855271 DOI: 10.1007/s00213-012-2817-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 07/16/2012] [Indexed: 12/26/2022]
Abstract
RATIONALE Sensory gating is an adaptive mechanism of the brain to prevent overstimulation. Patients suffering from clinical disorders such as Alzheimer's disease or schizophrenia exhibit a deficit in gating, which indicates not only an impairment in basic information processing that might contribute to the cognitive problems seen in these patients. Phosphodiesterase type 5 inhibitors (PDE5-Is) have been shown to improve cognition in rodents in various behavioural tasks and might consequently be an interesting target for cognition enhancement. However, the effects of PDE5-Is on sensory gating are not known yet. OBJECTIVES This work aims to study the effects of PDE5 inhibition on auditory sensory gating in rats and humans. METHODS In the rat study, vehicle or 0.3-3 mg/kg of the PDE5-I vardenafil was given orally 30 min before testing and electrode locations were the vertex, hippocampus and the striatum. The human subjects received placebo, 10-20 mg vardenafil 85 min before testing and sensory gating was measured at the cortex (Fz, Fcz and Cz) electrodes. RESULTS Significant gating was only found for the N1 component in rats while all three peaks P1, N1 and P2 showed gating in humans, i.e. the response to the second sound click was decreased as compared with the first for these deflections. Administration of vardenafil did neither have an effect on sensory gating in rats nor in humans. CONCLUSIONS These findings imply that positive effects of PDE5 inhibition on cognition are not mediated by more early phases of information processing.
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Affiliation(s)
- O A H Reneerkens
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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van Donkelaar EL, Blokland A, Ferrington L, Kelly PAT, Steinbusch HWM, Prickaerts J. Mechanism of acute tryptophan depletion: is it only serotonin? Mol Psychiatry 2011; 16:695-713. [PMID: 21339754 DOI: 10.1038/mp.2011.9] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The method of acute tryptophan depletion (ATD), which reduces the availability of the essential amino acid tryptophan (TRP), the dietary serotonin (5-hydroxytryptamine (5-HT)) precursor, has been applied in many experimental studies. ATD application leads to decreased availability of TRP in the brain and its synthesis into 5-HT. It is therefore assumed that a decrease in 5-HT release and subsequent blunted neurotransmission is the underlying mechanism for the behavioural effects of ATD. However, direct evidence that ATD decreases extracellular 5-HT concentrations is lacking. Furthermore, several studies provide support for alternative underlying mechanisms of ATD. This may question the utility of the method as a selective serotonergic challenge tool. As ATD is extensively used for investigating the role of 5-HT in cognitive functions and psychiatric disorders, the potential of alternative mechanisms and possible confounding factors should be taken into account. It is suggested that caution is required when interpreting ATD effects in terms of a selective serotonergic effect.
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Affiliation(s)
- E L van Donkelaar
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
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Doherty-Sneddon G, McAuley S, Bruce V, Langton S, Blokland A, Anderson AH. Visual signals and children's communication: Negative effects on task outcome. British Journal of Developmental Psychology 2010. [DOI: 10.1348/026151000165878] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Jans LAW, Korte-Bouws GAH, Korte SM, Blokland A. The effects of acute tryptophan depletion on affective behaviour and cognition in Brown Norway and Sprague Dawley rats. J Psychopharmacol 2010; 24:605-14. [PMID: 19074537 DOI: 10.1177/0269881108099424] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Previous studies in rats and humans have shown that the essential amino acid tryptophan (TRP) is depleted after consumption of a gelatin-based protein-carbohydrate mixture, which is lacking L-tryptophan (TRP-). In rats, TRP depletion caused impaired object recognition but only had a modest effect on affective behaviour. Because these studies were preformed with Wistar rats, the aim of the present experiment was to evaluate strain differences in behavioural responses to acute TRP depletion between Brown Norway (BN) and Sprague Dawley (SD) rats. The rats were repeatedly treated with TRP- or a balanced control (TRP+) and were tested in tests of anxiety- and depression-related behaviour (open-field test, home cage emergence test, social interaction test, forced swim test) and memory. SD rats, but not BNs, showed more anxiety- and depression-related behaviour and impaired object recognition after TRP- treatment. There was a dissociation between plasma TRP levels, central 5-HT concentrations and 5-HIAA/5-HT turnover. Both strains showed about 60% decrease in plasma TRP/SigmaLNAA levels, whereas hippocampal 5-HT levels were lower after TRP- in BN but not SD rats. Conversely, 5-HIAA/5-HT turnover was lower after TRP- in SD but not BN rats, suggesting a dissociation between 5-HT storage and release in SDs. The present study suggests that acute tryptophan depletion effects are strain dependent on the behavioural and the neurochemical level.
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Affiliation(s)
- L A W Jans
- Department of Neuropsychology & Psychopharmacology, Faculty of Psychology, Maastricht University, Maastricht, The Netherlands
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Olivier JDA, Jans LAW, Blokland A, Broers NJ, Homberg JR, Ellenbroek BA, Cools AR. Serotonin transporter deficiency in rats contributes to impaired object memory. Genes, Brain and Behavior 2009; 8:829-34. [DOI: 10.1111/j.1601-183x.2009.00530.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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van Donkelaar E, Ferrington L, Blokland A, Steinbusch H, Prickaerts J, Kelly P. Acute tryptophan depletion in rats alters the relationship between cerebral blood flow and glucose metabolism independent of central serotonin. Neuroscience 2009; 163:683-94. [DOI: 10.1016/j.neuroscience.2009.06.063] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 06/26/2009] [Accepted: 06/29/2009] [Indexed: 10/20/2022]
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Sambeth A, Riedel WJ, Tillie DE, Blokland A, Postma A, Schmitt JAJ. Memory impairments in humans after acute tryptophan depletion using a novel gelatin-based protein drink. J Psychopharmacol 2009; 23:56-64. [PMID: 18515454 DOI: 10.1177/0269881108089577] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Acute tryptophan depletion (ATD) can be used to decrease serotonin levels in the brain. Traditionally, ATD has been established by administering amino acid (AA) mixtures and studies using this method showed that serotonin is involved in learning and memory processes. This study used a recently developed gelatin-based protein drink to examine whether it 1) is superior to the traditional AA method in controlling the tryptophan levels in the placebo condition, 2) impairs long-term memory and 3) differentially affects episodic and spatial memory. Sixteen healthy subjects participated in a double-blind, placebo-controlled study. Memory was assessed using a visual verbal learning test and an object relocation task (spatial memory). Tryptophan ratio significantly decreased after ATD and did not significantly increase in the placebo condition. Delayed recall in the verbal learning test and delayed relocation of objects to positions in the spatial task were impaired after ATD. Spatial short-term memory, however, improved. The current results indicate that the tryptophan levels were essentially neutral in the placebo condition compared with those in the traditional AA mixture. Our study provides further evidence that impairment in long-term episodic and elementary spatial memory after ATD is related to lowered tryptophan levels in plasma.
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Affiliation(s)
- A Sambeth
- Faculty of Psychology & Neuroscience, Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
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Olivier JDA, Jans LAW, Korte-Bouws GAH, Korte SM, Deen PMT, Cools AR, Ellenbroek BA, Blokland A. Acute tryptophan depletion dose dependently impairs object memory in serotonin transporter knockout rats. Psychopharmacology (Berl) 2008; 200:243-54. [PMID: 18542930 DOI: 10.1007/s00213-008-1201-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 05/06/2008] [Indexed: 11/29/2022]
Abstract
RATIONALE Acute tryptophan depletion (ATD) transiently lowers central serotonin levels and can induce depressive mood states and cognitive defects. Previous studies have shown that ATD impairs object recognition in rats. OBJECTIVES As individual differences exist in central serotonin neurotransmission, the impact of ATD may vary accordingly. In this experiment, we investigated the hypothesis that male serotonin transporter knockout (SERT(-/-)), rats marked by a lower SERT function, are more vulnerable to the effects of ATD in an object recognition task than male wildtype (SERT(+/+)) and heterozygous (SERT(+/-)) rats. MATERIALS AND METHODS Twelve male SERT(+/+), SERT(+/-), and SERT(-/-) rats were treated with standard dose and low-dose ATD using a gelatine-based protein-carbohydrate mixture lacking tryptophan. In the control treatment, L: -tryptophan was added to the mixture. Four hours after treatment, the rats were subjected to the object recognition task. In addition, the effects of ATD on plasma amino acid concentrations were measured, and concentrations of 5-HT and 5-HIAA were measured in the frontal cortex and hippocampus of these rats. RESULTS Plasma TRP levels and central 5-HT and 5-HIAA levels were decreased in all genotypes after ATD, but effects were stronger in SERT(-/-) rats. The standard dose of ATD impaired object recognition in all genotypes. SERT(-/-) and SERT(+/-) rats were more vulnerable to low dose of ATD in the object recognition task compared to SERT(+/+) rats. CONCLUSIONS These results indicate a greater sensitivity to ATD in SERT(-/-) and SERT(+/-) rats, which may be related to stronger central depletion effects in these rats.
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Affiliation(s)
- J D A Olivier
- Department of Cognitive Neuroscience: Psychoneuropharmacology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
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Rutten K, Prickaerts J, Schaenzle G, Rosenbrock H, Blokland A. Sub-chronic rolipram treatment leads to a persistent improvement in long-term object memory in rats. Neurobiol Learn Mem 2008; 90:569-75. [DOI: 10.1016/j.nlm.2008.04.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 04/25/2008] [Accepted: 04/28/2008] [Indexed: 10/21/2022]
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Jans LAW, Lieben CKJ, Smits LT, Blokland A. Pharmacokinetics of acute tryptophan depletion using a gelatin-based protein in male and female Wistar rats. Amino Acids 2008; 37:349-57. [PMID: 18683016 PMCID: PMC2705715 DOI: 10.1007/s00726-008-0160-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 07/18/2008] [Indexed: 11/13/2022]
Abstract
The essential amino acid tryptophan is the precursor of the neurotransmitter serotonin. By depleting the body of tryptophan, brain tryptophan and serotonin levels are temporarily reduced. In this paper, several experiments are described in which dose and treatment effects of acute tryptophan depletion (ATD) using a gelatin-based protein–carbohydrate mixture were studied in male and female Wistar rats. Two or three doses of tryptophan depleting mixture resulted in 65–70% depletion after 2–4 h in males. ATD effects were similar in females, although females may return to baseline levels faster. Treatment effects after four consecutive days of ATD were similar to the effects of 1 day of treatment. Object recognition memory was impaired 2, 4, and 6 h after the first of two doses of ATD, suggesting that the central effects occurred rapidly and continued at least 6 h, in spite of decreasing treatment effects on plasma tryptophan levels at that time point. The method of acute tryptophan depletion described here can be used to study the relationship between serotonin and behaviour in both male and female rats.
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Affiliation(s)
- L A W Jans
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
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Rutten K, Basile JL, Prickaerts J, Blokland A, Vivian JA. Selective PDE inhibitors rolipram and sildenafil improve object retrieval performance in adult cynomolgus macaques. Psychopharmacology (Berl) 2008; 196:643-8. [PMID: 18034336 PMCID: PMC2244695 DOI: 10.1007/s00213-007-0999-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 10/23/2007] [Indexed: 11/29/2022]
Abstract
RATIONALE Selective phosphodiesterase (PDE) inhibitors improve the formation of hippocampus-dependent memories in several rodent models of cognition. However, studies evaluating the effects of PDE inhibition on prefrontal cortex-dependent cognition and in monkeys are rare. OBJECTIVES The present study investigates the effect of the PDE4 inhibitor rolipram and the PDE5 inhibitor sildenafil on object retrieval performance. Object retrieval is a prefrontal cortical-mediated task, which is likely to capture attention and response inhibition. MATERIALS AND METHODS The ability to retrieve a food reward from a clear box with an open side positioned in various orientations was assessed in adult male cynomolgus monkeys (Macaca fascicularis). RESULTS Rolipram (0.003-0.03 mg/kg, intramuscular [i.m.]) and sildenafil (0.3-3 mg/kg, i.m.) dose-dependently increased correct first reaches during difficult trials, reaching significance at 0.01 and 1 mg/kg, respectively. For both drugs, correct reaches were increased approximately 20%; that is, performance was improved from approximately 50 to approximately 70% correct. CONCLUSIONS Both rolipram and sildenafil improved object retrieval performance, thus demonstrating the cognition-enhancing effects of PDE inhibition on a prefrontal task of executive function in monkeys.
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Affiliation(s)
- K. Rutten
- Department of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, P.O. Box 616, 6200 MD Maastricht, The Netherlands ,Department of Neuroscience, Roche Pharmaceuticals Palo Alto, Palo Alto, CA USA
| | - J. L. Basile
- Department of Neuroscience, Roche Pharmaceuticals Palo Alto, Palo Alto, CA USA
| | - J. Prickaerts
- Department of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, P.O. Box 616, 6200 MD Maastricht, The Netherlands ,Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - A. Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - J. A. Vivian
- Department of Neuroscience, Roche Pharmaceuticals Palo Alto, Palo Alto, CA USA
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Rutten K, Reneerkens OAH, Hamers H, Sik A, McGregor IS, Prickaerts J, Blokland A. Automated scoring of novel object recognition in rats. J Neurosci Methods 2008; 171:72-7. [PMID: 18372047 DOI: 10.1016/j.jneumeth.2008.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/12/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
The object recognition task (ORT) has become increasingly popular as a memory test in neuroscience research. Scoring of ORT performance is still mostly done by hand, which can be liable to subjective scoring. To our knowledge, no suited software is available yet since the direction of the nose of the animal cannot be tracked reliably. We have developed a software paradigm that reliably tracks the nose of the rats and have conducted a series of experiments to evaluate the reliability of this newly developed program. We used Wistar rats, which showed good object memory after 1h interval. Subsequently, we used scopolamine (SCOP) to impair the memory performance of the rats. The object exploration was scored by two observers and the automated system. Both observers and the automated system found an impairing drug effect of scopolamine on ORT performance. When using large objects the correlation between the discrimination index d2 of observers was: 0.60 (SCOP) and 0.79 (SAL). However, the correlation between observers and the automated system was quite low: 0.41 (SCOP) and 0.40 (SAL). Reducing the size of the objects increased the reliability between observers and the automated system substantially (0.82-0.87). We conclude that the use of small objects in combination with our program enables reliable automated scoring in the ORT, thus increasing the objectivity and validity of this task.
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Affiliation(s)
- K Rutten
- Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.
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Freude S, Ehlkes T, Kopp V, Leeser U, Krone W, Schröder H, Blokland A, Schubert M. Fettreiche Ernährung induziert dosisabhängig eine zerebrale Insulinresistenz und vermindert die kognitive Leistung in vivo. DIABETOL STOFFWECHS 2008. [DOI: 10.1055/s-2008-1076265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Jans LAW, Lieben CKJ, Blokland A. Influence of sex and estrous cycle on the effects of acute tryptophan depletion induced by a gelatin-based mixture in adult Wistar rats. Neuroscience 2007; 147:304-17. [PMID: 17531394 DOI: 10.1016/j.neuroscience.2007.04.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 03/26/2007] [Accepted: 04/12/2007] [Indexed: 10/23/2022]
Abstract
Women are more vulnerable to develop depression and anxiety disorders than men. This may be related to higher serotonergic vulnerability in women. Serotonergic vulnerability entails that differences between people in the regulation of serotonin (5-HT) determine the vulnerability of an individual to develop depression or other 5-HT-related disorders. The aim of the present experiment was to evaluate whether male and female Wistar rats differ in serotonergic vulnerability. Here, a stronger behavioral response to acute tryptophan (TRP) depletion was assumed to reflect serotonergic vulnerability. Twenty-four male and 48 female rats were repeatedly subjected to treatment with a gelatin-based protein-carbohydrate mixture, either with or without L-tryptophan. Female estrous cycle phase was determined by means of vaginal smears and the females were divided into two groups based on their estrous cycle phase: pro-estrus/estrus and met-estrus/di-estrus. Blood samples showed stronger TRP depletion in males than females. There was no effect of estrous cycle on plasma TRP concentrations. In contrast, treatment effects on some brain TRP concentrations were influenced by estrous cycle phase, females in pro-estrus/estrus showed the strongest response to TRP depletion. In the open field test and home cage emergence test, females in pro-estrus/estrus also showed the strongest behavioral response to acute TRP depletion. In general, females showed more activity than males in anxiety-related situations and this effect appeared to be enhanced by TRP depletion. In the social interaction test, passive body contact in males and females in pro-estrus/estrus was decreased after TRP depletion whereas it was increased in females in the met-estrus/di-estrus phase. Acute TRP depletion affected object recognition, but did not affect behavior in the forced swimming test and a reaction time task. It is concluded that sex and estrous cycle phase can influence the behavioral response to TRP depletion, and that females in pro-estrus/estrus show the strongest behavioral response to acute TRP depletion.
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Affiliation(s)
- L A W Jans
- Department of Neurocognition, Faculty of Psychology, Maastricht University, 6200 MD Maastricht, The Netherlands.
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Rutten K, Lieben C, Smits L, Blokland A. The PDE4 inhibitor rolipram reverses object memory impairment induced by acute tryptophan depletion in the rat. Psychopharmacology (Berl) 2007; 192:275-82. [PMID: 17265077 PMCID: PMC1915617 DOI: 10.1007/s00213-006-0697-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Accepted: 12/28/2006] [Indexed: 10/27/2022]
Abstract
RATIONALE The selective type IV phosphodiesterase inhibitor, rolipram, has been shown to improve long-term memory and can reverse the cholinergic deficit caused by scopolamine. However, the underlying mechanisms of action of rolipram remain obscure. OBJECTIVES The present study investigates the effect of rolipram in a serotonergic-deficit model of acute tryptophan depletion (ATD). In addition, the levels of plasma tryptophan (TRP) were compared to object recognition performance. MATERIALS AND METHODS The experiments were conducted using male Wistar rats. The time-dependent effect of ATD treatment (a gelatin-based protein mixture) on plasma TRP levels (0, 1, 3, and 6 h after injection) and object recognition task (ORT) performance (0.5, 1, 3, and 6 h after ATD treatment) was examined. The effect of rolipram (0, 0.01, 0.03, and 0.1 mg/kg, i.p.) was tested in the condition in which ATD induced a clear memory deficit. RESULTS ATD significantly lowered the plasma TRP ratio (TRP/Sigmalarge neutral amino acid) with a maximum of 48%, approximately 1 h after administration. Furthermore, ATD impairs ORT performance when administered 3 h before testing. Rolipram (0.1 mg/kg) reversed the memory deficit induced by ATD in a dose-dependent manner. CONCLUSIONS On the basis of previous studies and the ability to reverse a serotonergic deficit, we suggest that rolipram may act through elevation of cyclic adenosine monophosphate levels and subsequent increase in neurotransmitter release.
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Affiliation(s)
- K Rutten
- Department of Psychiatry and Neuropsychology, Brain and Behavior Institute, Maastricht University, Universiteitssingel 50, 6200 MD, Maastricht, The Netherlands.
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Abstract
In recent years, the term serotonergic vulnerability (SV) has been used in scientific literature, but so far it has not been explicitly defined. This review article attempts to elucidate the SV concept. SV can be defined as increased sensitivity to natural or experimental alterations of the serotonergic (5-HTergic) system. Several factors that may disrupt the 5-HTergic system and hence contribute to SV are discussed, including genetic factors, female gender, personality characteristics, several types of stress and drug use. It is explained that SV can be demonstrated by means of manipulations of the 5-HTergic system, such as 5-HT challenges or acute tryptophan depletion (ATD). Results of 5-HT challenge studies and ATD studies are discussed in terms of their implications for the concept of SV. A model is proposed in which a combination of various factors that may compromise 5-HT functioning in one person can result in depression or other 5-HT-related pathology. By manipulating 5-HT levels, in particular with ATD, vulnerable subjects may be identified before pathology initiates, providing the opportunity to take preventive action. Although it is not likely that this model applies to all cases of depression, or is able to identify all vulnerable subjects, the strength of the model is that it may enable identification of vulnerable subjects before the 5-HT related pathology occurs.
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Affiliation(s)
- L A W Jans
- Faculty of Psychology, Department of Neurocognition, Maastricht University, Maastricht, The Netherlands.
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Abstract
During the last decennia, our understanding of the neurobiological processes underlying learning and memory has continuously improved, leading to the identification of targets for the development of memory-enhancing drugs. Here we review a class of drugs which has more recently been identified: the phosphodiesterase (PDE) inhibitors. An overview is given of the different PDEs that are known and we focus on three PDEs which have been identified as possible relevant targets for memory improvement: PDE2, PDE4 and PDE5. PDEs differ in the substrate, i.e. cyclic adenosine monophosphate (cAMP) and/or cyclic guanosine monophosphate (cGMP), being hydrolyzed. Since these cyclic nucleotides have been suggested to play distinct roles in processes of memory, selective PDE inhibitors preventing the breakdown of cAMP and/or cGMP could improve memory. The present data suggest that PDE4 (cAMP) is involved in acquisition processes, although a possible role in late consolidation processes cannot be excluded. PDE5 (cGMP) is involved in early consolidation processes. Since PDE2 inhibition affects both cAMP and cGMP, PDE2 inhibitors may improve both memory processes. The field of PDEs is highly dynamic and new isoforms of PDEs are still being described. This may lead to the discovery and development of new memory enhancing drugs that selectively inhibit such isoforms. Such drugs may exert their effects only in specific brain areas and hence possess an improved side effect profile.
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Affiliation(s)
- A Blokland
- Department of Psychology, Brain & Behavior Institute, EURON, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Rutten K, Vente JD, Sik A, Ittersum MMV, Prickaerts J, Blokland A. The selective PDE5 inhibitor, sildenafil, improves object memory in Swiss mice and increases cGMP levels in hippocampal slices. Behav Brain Res 2006; 164:11-6. [PMID: 16076505 DOI: 10.1016/j.bbr.2005.04.021] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 04/27/2005] [Accepted: 04/29/2005] [Indexed: 11/20/2022]
Abstract
Previous studies have shown memory enhancing effects of phosphodiesterase type 5 (PDE5) inhibitors in rats. However, differences in nitric oxide (NO)-mediated cyclic GMP (cGMP) signaling in the hippocampus have been described between rats and mice. In the present study we investigated the memory enhancing effects of the PDE5 inhibitor, sildenafil on memory performance in Swiss mice using the object recognition task. Sildenafil (0.3, 1 and 3 mg/kg) was administered orally directly after the first trial. The memory for the objects was retested 24 h later when mice show no memory for the familiar object. Sildenafil improved the object discrimination performance of Swiss mice at a dose of 1 mg/kg. Hippocampal slices of Swiss mice incubated with sildenafil (10 microM) increased cGMP levels in varicosities in the CA3 region of the hippocampus and a number of short, thin fibers. Addition of DEA/NO, an NO donor (10 microM), in the presence of sildenafil (10 microM) strongly increased cGMP immunoreactivity of varicosities in the CA3 region. Double immunostaining of cGMP with the presynaptic marker synaptophysin did not reveal any co-localization of these markers under any circumstance. Taken together, inhibition of PDE5 improves object recognition memory in mice. Furthermore, a postsynaptic role of cGMP could be involved in this respect.
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Affiliation(s)
- K Rutten
- Department of Psychiatry and Neuropsychology, Brain and Behavior Institute, Maastricht University, The Netherlands.
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Rutten K, Prickaerts J, Blokland A. Rolipram reverses scopolamine-induced and time-dependent memory deficits in object recognition by different mechanisms of action. Neurobiol Learn Mem 2005; 85:132-8. [PMID: 16242977 DOI: 10.1016/j.nlm.2005.09.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 09/01/2005] [Accepted: 09/08/2005] [Indexed: 11/24/2022]
Abstract
In this study, the effect of the selective phosphodiesterase type 4 (PDE4) inhibitor rolipram on memory performance was investigated using the object recognition task. First, three doses of rolipram (0.01, 0.03 or 0.1 mg/kg) were tested with a 24h delay between the learning (T1) and the test (T2) trial. Doses of rolipram were injected at different time points (30 min before T1, immediately after T1 or 3 h after T1). In a second experiment, the effects of rolipram (0.03, 0.1 or 0.3 mg/kg) were tested in combination with scopolamine (0.1 mg/kg) applying a 1 h delay between trials. Both substances were administered 30 min before T1. Using a 24h interval, rolipram showed an improvement in long-term memory performance when injected 3 h after T1 at a dose of 0.03 mg/kg. Further, rolipram reversed the scopolamine-induced short-term memory deficit at a dose of 0.1 mg/kg. Although the improved memory performance in both conditions is likely to be explained by elevated cAMP levels, two separate working mechanisms might explain these effects.
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Affiliation(s)
- K Rutten
- Department of Psychiatry and Neuropsychology, Brain and Behaviour Institute, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Abstract
We examined the effects of DOI (2,5-dimethoxy-4-iodoamphetamine), 8-OH-DPAT (8-hydroxy-2-(N,N-dipropylamino)tetralin, eticlopride and amphetamine in a reaction time (RT) task. In this task a trial is initiated after a rat pushes a panel. Rats have to wait (0.5-1.5 s) until a tone is presented before making a response. The number of premature responses, releasing the panel before tone was switched on, was taken as a measure of motor impulsivity. A group of 10 Lewis rats was tested in the RT task after treatment with different doses of drugs which have been shown previously to affect impulsive responding: DOI (0.1, 0.2 mg/kg), 8-OH-DPAT (0.1, 0.3 mg/kg), eticlopride (0.01, 0.03 mg/kg) and D-amphetamine (0.3, 1 mg/kg). A progressive ratio test was used to control for drug effects on food motivation. DOI (0.1 mg/kg) and D-amphetamine (0.3 mg/kg) increased impulsive responding in the RT task. Conversely, 8-OH-DPAT decreased impulsive responding in the RT task. These effects of DOI, D-amphetamine and 8-OH-DPAT on impulsive responding were not associated with changes in food motivation, as assessed by performance in the progressive ratio task. Eticlopride did not affect impulsive responding. The present data suggest that 5-HT2A receptors and dopamine (but not D2 receptors) are associated with motor impulsivity.
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Affiliation(s)
- A Blokland
- Faculty of Psychology, Brain am Behaviour Institute and European Graduate School of Neurosciences, Maastricht University, The Netherlands.
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Lieben CKJ, Blokland A, Westerink B, Deutz NEP. Acute tryptophan and serotonin depletion using an optimized tryptophan-free protein-carbohydrate mixture in the adult rat. Neurochem Int 2004; 44:9-16. [PMID: 12963083 DOI: 10.1016/s0197-0186(03)00102-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In contrast to humans, a tryptophan (TRP)-free amino acid (AA) mixture only leads to moderate depletion in plasma TRP levels in adult rats. In this study we evaluated the effects of an acute administration of a TRP-free protein-carbohydrate nutritional mixture in adult male Wistar rats. Plasma amino acid levels were examined at 2 and 4h starting after the first administration. Furthermore, the concentrations of amino acid, serotonin (5-HT), dopamine (DA) and their metabolite (5-hydroxyindolacetic acid (5-HIAA) and 3,4-dihydroxyphenylacetic acid (DOPAC), respectively) were measured within the striatum, hippocampus and cortex. In the TRP depleted animals, the TRP/sigmaLNAA ratio (LNAA: large neutral amino acids) was substantial decreased at 2 and 4h after the first administration of the oral administration (by 71 and 78%, respectively). Four hours after treatment central TRP and 5-HT concentrations were decreased by 50%. Both peripheral and central TRP levels returned to basal values in the group treated with the nutritional mixture supplemented with TRP. Surprisingly, tyrosine levels were also reduced after oral administration of the protein-carbohydrate mixture without affecting central DA concentrations. In conclusion, the TRP-free protein-carbohydrate nutritional mixture appears to be an efficient tool to substantially reduce plasma and central TRP levels in adult rat.
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Affiliation(s)
- C K J Lieben
- Department of Neuropsychology and Psychiatry, Brain and Behavior Institute, University of Maastricht, P.O. Box 616, Maastricht MD 6200, The Netherlands.
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Blokland A, Broersen L, Uylings H, Jolles J. Intact spatial discrimination performance but impaired reaction time performance after frontal cortex lesions in the rat. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/nrc.10076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Van de Berg WDJ, Kwaijtaal M, de Louw AJA, Lissone NPA, Schmitz C, Faull RLM, Blokland A, Blanco CE, Steinbusch HWM. Impact of perinatal asphyxia on the GABAergic and locomotor system. Neuroscience 2003; 117:83-96. [PMID: 12605895 DOI: 10.1016/s0306-4522(02)00787-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Perinatal asphyxia can cause neuronal loss and depletion of neurotransmitters within the striatum. The striatum plays an important role in motor control, sensorimotor integration and learning. In the present study we investigated whether perinatal asphyxia leads to motor deficits related to striatal damage, and in particular to the loss of GABAergic neurons. Perinatal asphyxia was induced in time-pregnant Wistar rats on the day of delivery by placing the uterus horns, containing the pups, in a 37 degrees C water bath for 20 min. Three motor performance tasks (open field, grip test and walking pattern) were performed at 3 and 6 weeks of age. Antibodies against calbindin and parvalbumin were used to stain GABAergic striatal projection neurons and interneurons, respectively. The motor tests revealed subtle effects of perinatal asphyxia, i.e. small decrease in motor activity. Analysis of the walking pattern revealed an increase in stride width at 6 weeks of age after perinatal asphyxia. Furthermore, a substantial loss of calbindin-immunoreactive (-22%) and parvalbumin-immunoreactive (-43%) cells was found in the striatum following perinatal asphyxia at two months of age. GABA(A) receptor autoradiography revealed no changes in GABA binding activity within the striatum, globus pallidus or substantia nigra. We conclude that perinatal asphyxia resulted in a loss of GABAergic projection neurons and interneurons in the striatum without alteration of GABA(A) receptor affinity. Despite a considerable loss of striatal neurons, only minor deficits in motor performance were found after perinatal asphyxia.
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Affiliation(s)
- W D J Van de Berg
- Department of Pediatrics, Research Institute Growth and Development (GROW), University of Maastricht, The Netherlands.
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Abstract
BACKGROUND AND OBJECTIVE General anaesthesia may contribute to postoperative cognitive decline in the elderly. The aim was to determine the effects of repeated pentobarbital anaesthesia throughout life on central cholinergic function in the rat. METHODS Young Lewis rats were randomly allocated to two groups. The anaesthesia group (n = 15) was anaesthetized with pentobarbital 20 mg kg(-1) intraperitoneally at 6, 8.5, 11, 13.5, 16, 18.5, 21 and 23.5 months of age. The control group (n = 12) was treated identically, apart from the anaesthesia. At 26 months of age, the animals were killed and the brain dissected and stored for analysis. Central cholinergic function in the cortex and hippocampus was assessed by measuring [3H]-epibatidine and [125I]alpha-bungarotoxin binding to nicotinic receptors and choline acetyltransferase (ChAT) activity. RESULTS Tissue from nine rats in the anaesthesia group and eight in the control group was available for analysis. There was a significant reduction in alpha-bungarotoxin binding in the anaesthetized compared with the control group in the superior cortex (P < 0.0002) and molecular cortex (P < 0.04). There were no significant differences between the groups for epibatidine binding or ChAT. CONCLUSIONS Repeated anaesthesia in rat reduces central nicotinic cholinergic binding in the cortex. The findings may have implications for postoperative cognitive function studies.
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Affiliation(s)
- C D Hanning
- Leicester General Hospital, Department of Anaesthesia, Leicester, UK.
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Prickaerts J, van Staveren WCG, Sik A, Markerink-van Ittersum M, Niewöhner U, van der Staay FJ, Blokland A, de Vente J. Effects of two selective phosphodiesterase type 5 inhibitors, sildenafil and vardenafil, on object recognition memory and hippocampal cyclic GMP levels in the rat. Neuroscience 2002; 113:351-61. [PMID: 12127092 DOI: 10.1016/s0306-4522(02)00199-9] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study investigated the effects of two cyclic GMP-specific phosphodiesterase enzyme type 5 inhibitors, sildenafil and vardenafil, on the memory performance in the object recognition task. Both compounds were given per orally (1, 3 and 10 mg/kg sildenafil; 0.1, 0.3, 1 and 3 mg/kg vardenafil) immediately after the exposure to two identical objects. The memory for the objects was tested 24 h later. Vehicle-treated rats spent equal times exploring a new and the familiar object demonstrating that they did not remember the familiar one. However, sildenafil improved the object discrimination performance of the rats with a high discrimination performance at a dose of 3 mg/kg. Rats treated with vardenafil also showed an improved object discrimination performance. Compared with sildenafil, vardenafil appeared to be even more potent in this respect since it already produced a high discrimination performance at a dose of 0.3 mg/kg. The effects of both compounds on cyclic GMP and cyclic AMP accumulation were studied in rat hippocampal slices incubated in vitro. Cyclic GMP levels were increased after incubation with the highest concentration of 100 microM vardenafil (together with 0.1 mM sodium nitroprusside), although no changes in cyclic GMP levels were detected after incubation with different concentrations of sildenafil. Both compounds had no effect on cyclic AMP levels. Additional cyclic GMP immunocytochemistry showed that incubation with vardenafil (in the presence of sodium nitroprusside) resulted in a concentration-dependent staining of cyclic GMP. Staining was predominantly found in neuronal fibres in the hippocampal CA2/CA3 region. It was already detected at a concentration of 0.1 microM vardenafil. Also positive fibres were detected after incubation with sildenafil but at a higher concentration of 10 microM. Taken together, these results suggest that inhibition of phosphodiesterase enzyme type 5 improves object recognition memory. This effect might be explained by increased levels of central cyclic GMP.
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Affiliation(s)
- J Prickaerts
- Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience EURON, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
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Blokland A, Honig W, Jolles J. Long-term consequences of repeated pentobarbital anaesthesia on choice reaction time performance in ageing rats. Br J Anaesth 2001; 87:781-3. [PMID: 11878533 DOI: 10.1093/bja/87.5.781] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recent studies have suggested that anaesthesia may be a factor in cognitive decline with age. We examined the effect of repeated (eight times) anaesthesia with pentobarbital on reaction time performance in rats in a longitudinal study. Treated rats had faster response times and made more premature responses than the control rats when they were older than 21 months. The results suggest that repeated anaesthesia during the lifespan can lead to an increase in impulsivity, as assessed by a choice reaction time test, during the later stages of life in the rat. These findings support the theory that repeated anaesthesia is a biological factor that affects cognitive ageing.
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Affiliation(s)
- A Blokland
- Faculty of Psychology, Maastricht Brain & Behaviour Institute, Maastricht University, The Netherlands
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Abstract
The most pronounced side effect of antiallergic histaminergic drugs (H1 antagonists) is sedation. These effects have been linked with the effects of histaminergic drugs on central H1 receptors. In the present study, we investigated the dose-response relationship of different antihistamines on the performance in a reaction-time task that has been developed for rats. The dose-response relationship of diphenhydramine, cetirizine and terfenadine were examined for the various behavioural measures in this task (i.e., reaction time, motor time, premature responses and number of trials completed). In addition, the effects of scopolamine were assessed to evaluate the cholinergic profile in this task. Diphenhydramine did not reliably affect the reaction time, but increased the motor time and the proportion of premature responses, and decreased the number of trials completed in a session. A low dose of cetirizine decreased the reaction time, whereas an increase in reaction time was found for the high dose. The motor time was increased after both doses of cetirizine. Terfenadine did not affect the responding of rats in the reaction-time task at the doses tested. The effects of scopolamine were very similar to those of diphenhydramine. The reaction-time task used in this study was able to dissociate different types of antihistamines on aspects of psychomotor function, which were likely to be related to central muscarinic or H1 antagonism. These findings suggest that the reaction-time task may be a sensitive tool for assessing effects of drugs on psychomotor function.
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Affiliation(s)
- A Blokland
- Maastricht Brain and Behaviour Institute, Faculty of Psychology, Section Neurocognition, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Mulder M, Blokland A, van den Berg DJ, Schulten H, Bakker AH, Terwel D, Honig W, de Kloet ER, Havekes LM, Steinbusch HW, de Lange EC. Apolipoprotein E protects against neuropathology induced by a high-fat diet and maintains the integrity of the blood-brain barrier during aging. J Transl Med 2001; 81:953-60. [PMID: 11454984 DOI: 10.1038/labinvest.3780307] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
SUMMARY The present study provides evidence that chronic intake of a high-fat diet induces a dramatic extravasation of immunoglobulins, indicating alterations in blood-brain barrier (BBB) functioning, in the brains of apolipoprotein E (apoE)-knockout mice, but not of C57Bl/6 control mice. Using sodium fluorescein as a marker for the permeability of the BBB, we found additional support for age-related disturbances of BBB function in apoE-knockout mice. Behavioral analysis of apoE-knockout mice compared with C57Bl/6 mice indicated that they were also less efficient in acquiring the spatial Morris water maze task. Furthermore, apoE-knockout mice are known to develop severe atherosclerosis, which is exacerbated with a high-fat diet. We therefore compared the apoE-knockout mice with the apoE3-Leiden transgenic mice, which are known to develop atherosclerosis. However, apoE3-Leiden mice that were kept on a high-fat, high-cholesterol diet and that developed atherosclerosis to an extent similar to the apoE-knockout mice, showed no signs of BBB disturbances. These results indicate for the first time that apoE plays an essential role in the maintenance of the integrity of the BBB during aging and that it protects the brain from neuropathology induced by a high-fat diet. We therefore hypothesize that the role of apoE in the maintenance of the integrity of the BBB may be the mechanism by which apoE affects the progression of neurodegeneration, as seen in Alzheimer's disease.
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Affiliation(s)
- M Mulder
- Department of Psychiatry and Neuropsychology, Faculty of Medicine, Maastricht University, Maastricht, The Netherlands.
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Abstract
Neurodegenerative diseases, traumatic brain injury and stroke are likely to result in cognitive dysfunctioning. Animal models are needed in which these deficits and recovery of the affected functions can be investigated. In the present study, the entorhinal area was chosen as the target for lesioning and for assessing the lesion-induced deficits in the Morris water maze. The entorhinal cortex is regarded as an interface between the hippocampus and neocortex. Deafferentiating the hippocampus through entorhinal lesions impairs spatial learning. The effects of lesions, induced by either electrocoagulation (experiment 1) or ibotenate excitotoxicity (experiment 2), on spatial orientation behaviour were investigated. Water maze performance after unilateral or bilateral ibotenate injections into the entorhinal cortex was studied in the third experiment. In an additional study, the replicability of the spatial learning deficit after lesions induced by bilateral injections of ibotenic acid into the entorhinal cortex was assessed by comparing the results of nine experiments. We found that spatial learning was impaired after bilateral lesions aimed at the entorhinal cortex. The electrolytic lesion technique produced a relatively large sham effect, whereas the excitotoxic lesioning method did not. Unilateral injections of ibotenic acid into the entorhinal cortex did not affect spatial navigation. The ibotenate-induced lesions replicably produced deficits in the Morris tasks. The degree of the induced spatial learning impairments and the effects on the rate of acquisition during training, however, differed between experiments. This result suggests that the fundamental biological diversity between shipments of rats can account for variation in the effects of parahippocampal damage on spatial learning even in highly standardized experimental set-ups. Rats lesioned by bilateral injections of ibotenic acid into the entorhinal cortex provide an interesting and reliable model for investigating cognitive dysfunctions in neurodegenerative diseases, stroke or traumatic brain injury.
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Prickaerts J, De Vente J, Honig W, Steinbusch H, Blokland A, Steinbusch HW. Nitric oxide synthase does not mediate neurotoxicity after an i.c.v. injection of streptozotocin in the rat. J Neural Transm (Vienna) 2001; 107:745-66. [PMID: 11005541 DOI: 10.1007/s007020070056] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the present study we evaluated the possible role of nitric oxide (NO) in mediating neuronal damage in middle-aged rats after an i.c.v. injection of streptozotocin (STREP). An i.c.v. injection of STREP has been reported to decrease the central metabolism of glucose. This inhibition of the energy metabolism after STREP treatment might induce an excitotoxic mechanism, which may lead to the stimulation of NO synthase and, consequently to the synthesis of NO. On the other hand, STREP might induce oxidative stress directly by liberation of NO from its nitroso moiety. To investigate whether NO synthase is involved in a possible excitotoxic mechanism after STREP treatment, some of the rats treated with STREP (1.25 mg/ kg in 4 microl, bilaterally 2 microl/injection site) were also treated with the NO synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME, 20 mg/kg i.p. 10 min, 6, 24 and 96 h after STREP injection). To investigate whether NO liberated from STREP may be responsible for neurotoxic effects, one additional group of control rats received an i.c.v. injection of the NO donor sodium nitroprusside (SNP, 10 microg in 4 microl). We found that STREP affected the behavioral performances in the open field and two-way active avoidance task. In addition, immunostaining for glial fibrillary acidic protein, an indicator of reactive astroglial changes to neuronal damage, showed that this was mainly located in peri- and paraventricular regions of the third and lateral ventricles, like for instance in the septum, caudate putamen and hippocampus. L-NAME treatment had no protective effect on the behavioral impairments and neuronal damage of STREP-treated rats. This suggests that the neuronal damage of STREP may still be a result of the decrease in the central energy metabolism, but without the involvement of NO synthase. This was supported by measuring, using immunostaining, the NO-mediated cyclic GMP production by the enzyme soluble guanylyl cyclase in cortical slices, i.e. L-NAME did not prevent NO production after STREP administration in vitro. In addition, it was found that SNP liberated NO in vitro, whereas in vivo SNP administration did not lead to any behavioral and neuronal deficits at all. However, the present study cannot exclude the involvement of NO liberated from STREP in neuronal damage.
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Affiliation(s)
- J Prickaerts
- Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience, Maastricht University, The Netherlands.
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Van de Berg WD, Blokland A, Cuello AC, Schmitz C, Vreuls W, Steinbusch HW, Blanco CE. Perinatal asphyxia results in changes in presynaptic bouton number in striatum and cerebral cortex-a stereological and behavioral analysis. J Chem Neuroanat 2000; 20:71-82. [PMID: 11074345 DOI: 10.1016/s0891-0618(00)00078-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Deficits in cognitive function have been related to quantitative changes in synaptic population, particularly in the cerebral cortex. Here, we used an established model of perinatal asphyxia that induces morphological changes, i.e. neuron loss in the cerebral cortex and striatum, as well as behavioural deficits. We hypothesized that perinatal asphyxia may lead to a neurodegenerative process resulting in cognitive impairment and altered presynaptic bouton numbers in adult rats. We studied cognitive performance at 18 months and presynaptic bouton numbers at 22 months following perinatal asphyxia. Data of the spatial Morris water escape task did not reveal clear memory or learning deficits in aged asphyctic rats compared to aged control rats. However, a memory impairment in aged rats versus young rats was observed, which was more pronounced in asphyctic rats. We found an increase in presynaptic bouton density in the parietal cortex, whereas no changes were found in striatum and frontal cortex in asphyctic rats. An increase of striatal volume was observed in asphyctic rats, leading to an increase in presynaptic bouton numbers in this area. These findings stress the issue that volume measurements have to be taken into account when determining presynaptic bouton density. Furthermore, perinatal asphyxia led to region-specific changes in presynaptic bouton numbers and it worsened the age-related cognitive impairment. These results suggest that perinatal asphyxia induced neuronal loss, which is compensated for by an increase in presynaptic bouton numbers.
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Affiliation(s)
- W D Van de Berg
- Department of Pediatrics, Maastricht University, P. Debyelaan 25, PO Box 5800, 6212 AZ, Maastricht, The Netherlands.
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Loidl CF, Gavilanes AW, Van Dijk EH, Vreuls W, Blokland A, Vles JS, Steinbusch HW, Blanco CE. Effects of hypothermia and gender on survival and behavior after perinatal asphyxia in rats. Physiol Behav 2000; 68:263-9. [PMID: 10716534 DOI: 10.1016/s0031-9384(99)00125-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Previous studies in rats have demonstrated that perinatal asphyxia (PA) produces long-term morphological alterations, particularly affecting hippocampus. neostriatum, and cerebral cortex. These changes were prevented by applying hypothermia during the asphyctic insult. Because these cerebral areas are involved in cognitive and motor functions, the aim of the present study was to determine whether periods of PA during normothermia or hypothermia produces long-term behavioral impairments in rats of both sexes. The cognitive and motor functions were studied using the spatial Morris water maze (MWM) task at 1.5 months, and the open field at 5 months, respectively. The present study revealed that female rats had a higher survival rate than males after PA in normothermic conditions (p < 0.014). and that hypothermia drastically prolonged the time of survival in both sexes (p < 0.001). There were no differences in learning and memory functions between groups or male and female rats when tested with MWM. Rats subjected to hypothermia treatment did not show differences in the MWM compared to controls. A lower locomotor activity in the open field test was only observed in male rats that suffered 15 and 20 min of PA in normothermia (p < 0.05). Hypothermia treatment prevented this hypoactivity. PA in females, even if severe, did not affect the motor activity. The data of both behavioral tests showed differences between sexes, i.e., the female rats learned the MWM task slower, and were more active in the open field. This work lends further support for the hypothesis that hypothermia can prevent mortality as well as long-term sequelae induced by PA.
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Affiliation(s)
- C F Loidl
- Department Of Pediatrics, Maastricht University And Academic Hospital Of Maastricht, The Netherlands
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van der Staay FJ, Fanelli RJ, Blokland A, Schmidt BH. Behavioral effects of apamin, a selective inhibitor of the SK(Ca)-channel, in mice and rats. Neurosci Biobehav Rev 1999; 23:1087-110. [PMID: 10643819 DOI: 10.1016/s0149-7634(99)00043-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Apamin, a highly selective and potent peptide that blocks the SK(Ca)-channels has been suggested to be a cognition enhancer. We tested apamin in the Morris water escape task, in shock motivated avoidance tasks, and in operant tasks in the Skinnerbox. We also used non-cognitive tests, such as the rat forced swimming test and cocaine-induced locomotor activity in the open field, and a test to assess the side effect profile. Mice and rats from different strains, and rats of different ages were used. The rat studies provided only weak support for the notion that apamin acts as a cognition enhancer. More convincing evidence was obtained from the mouse studies. Overt side effects of apamin were found at the dose of 0.3 mg kg(-1). This dose was close to, or even overlapped, the doses which improved cognition in mice. We conclude that apamin is a poor tool to assess the role of SK(Ca)-channels in learning and memory processes.
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