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Rasmussen EB, Newland MC, Hemmelman E. The Relevance of Operant Behavior in Conceptualizing the Psychological Well-Being of Captive Animals. Perspect Behav Sci 2020; 43:617-654. [PMID: 33029580 PMCID: PMC7490306 DOI: 10.1007/s40614-020-00259-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The term "psychological well-being" is used in reference to husbandry with animals in human care settings such as research, agriculture, and zoos. This article seeks to clarify and conceptualize the term based upon two approaches that draw from several bodies of literature: the experimental analysis of behavior, experimental psychology, animal welfare and husbandry, farm animal behavior, zoo husbandry, and ethology. One approach focuses on the presence of problem behavior such as stereotypies, depressive-like behavior, and aggression, and emphasizes the conditions under which aberrant behavior in animals under human care occurs. The second approach examines what might be considered wellness by emphasizing opportunities to engage with its environment, or the absence of such opportunities, even if problematic behavior is not exhibited. Here, access to an interactive environment is relatively limited so opportunities for operant (voluntary) behavior could be considered. Designing for operant behavior provides opportunities for variability in both behavior and outcomes. Operant behavior also provides control over the environment, a characteristic that has been a core assumption of well-being. The importance of interactions with one's environment is especially evident in observations that animals prefer opportunities to work for items necessary for sustenance, such as food, over having them delivered freely. These considerations raise the importance of operant behavior to psychological well-being, especially as benefits to animals under human care.
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Affiliation(s)
- Erin B. Rasmussen
- Department of Psychology, Idaho State University, Pocatello, ID 83209-8112 USA
| | | | - Ethan Hemmelman
- Department of Psychology, Idaho State University, Pocatello, ID 83209-8112 USA
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Frederick MJ, Cocuzzo SE. Contrafreeloading in Rats Is Adaptive and Flexible: Support for an Animal Model of Compulsive Checking. EVOLUTIONARY PSYCHOLOGY 2017; 15:1474704917735937. [PMID: 29073770 PMCID: PMC10481083 DOI: 10.1177/1474704917735937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/14/2017] [Indexed: 01/01/2023] Open
Abstract
Contrafreeloading involves working unnecessarily to obtain a reward that is otherwise freely available. It has been observed in numerous species and can be adaptive when it provides an organism with updated information about available resources. Humans frequently update their knowledge of the environment through checking behaviors. Compulsive checking occurs when such actions are performed with excessive frequency. In a putative animal model of compulsive checking, rats treated chronically with the dopamine agonist quinpirole display exaggerated contrafreeloading for water. Although this effect has been attributed to behavioral rigidity, some evidence suggests the behavior remains somewhat flexible and may be adaptive under certain conditions. We assessed the ability of quinpirole-treated rats with contrafreeloading experience to adapt to changing contingencies by requiring them to alternate between response levers. Rats treated with quinpirole or saline were first trained to obtain water by pressing either of two levers. Next, free water was made available for 8 days, and contrafreeloading was measured. Rates of contrafreeloading were significantly higher in the drug-treated rats than in controls. On the following 5 days, each reward caused the associated lever to become inactive until a reward was earned from the alternate lever. Quinpirole-treated rats learned this new response requirement more quickly than controls. Thus, exaggerated checking behavior induced by chronic quinpirole treatment can be advantageous when environmental contingencies change. These results provide support for this animal model of compulsive checking and hint at the presence of a specialized neural checking module involving the dopamine system.
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Affiliation(s)
- Michael J. Frederick
- Division of Applied Behavioral Sciences, University of Baltimore, Baltimore, MD, USA
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Szechtman H, Ahmari SE, Beninger RJ, Eilam D, Harvey BH, Edemann-Callesen H, Winter C. Obsessive-compulsive disorder: Insights from animal models. Neurosci Biobehav Rev 2017; 76:254-279. [PMID: 27168347 PMCID: PMC5833926 DOI: 10.1016/j.neubiorev.2016.04.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/22/2016] [Accepted: 04/26/2016] [Indexed: 01/15/2023]
Abstract
Research with animal models of obsessive-compulsive disorder (OCD) shows the following: (1) Optogenetic studies in mice provide evidence for a plausible cause-effect relation between increased activity in cortico-basal ganglia-thalamo-cortical (CBGTC) circuits and OCD by demonstrating the induction of compulsive behavior with the experimental manipulation of the CBGTC circuit. (2) Parallel use of several animal models is a fruitful paradigm to examine the mechanisms of treatment effects of deep brain stimulation in distinct OCD endophenotypes. (3) Features of spontaneous behavior in deer mice constitute a rich platform to investigate the neurobiology of OCD, social ramifications of a compulsive phenotype, and test novel drugs. (4) Studies in animal models for psychiatric disorders comorbid with OCD suggest comorbidity may involve shared neural circuits controlling expression of compulsive behavior. (5) Analysis of compulsive behavior into its constitutive components provides evidence from an animal model for a motivational perspective on OCD. (6) Methods of behavioral analysis in an animal model translate to dissection of compulsive rituals in OCD patients, leading to diagnostic tests.
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Affiliation(s)
- Henry Szechtman
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada.
| | - Susanne E Ahmari
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Richard J Beninger
- Departments of Psychology and Psychiatry, Queen's University, Kingston, ON, Canada.
| | - David Eilam
- Department of Zoology, Tel-Aviv University, Ramat-Aviv 69978, Israel.
| | - Brian H Harvey
- MRC Unit on Anxiety and Stress Disorders, Center of Excellence for Pharmaceutical Sciences, School of Pharmacy, North-West University, Potchefstroom, South Africa.
| | - Henriette Edemann-Callesen
- Bereich Experimentelle Psychiatrie, Klinik und Poliklinik für Psychiatrie und Psychotherapie, Universitätsklinikum Carl Gustav Carus an der Technischen Universität Dresden, Dresden, Germany.
| | - Christine Winter
- Bereich Experimentelle Psychiatrie, Klinik und Poliklinik für Psychiatrie und Psychotherapie, Universitätsklinikum Carl Gustav Carus an der Technischen Universität Dresden, Dresden, Germany.
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Podlesnik CA, Jimenez-Gomez C. Contrafreeloading, reinforcement rate, and behavioral momentum. Behav Processes 2016; 128:24-8. [DOI: 10.1016/j.beproc.2016.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 11/28/2022]
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Schepisi C, Pignataro A, Doronzio SS, Piccinin S, Ferraina C, Di Prisco S, Feligioni M, Pittaluga A, Mercuri NB, Ammassari-Teule M, Nisticò R, Nencini P. Inhibition of hippocampal plasticity in rats performing contrafreeloading for water under repeated administrations of pramipexole. Psychopharmacology (Berl) 2016; 233:727-37. [PMID: 26572895 DOI: 10.1007/s00213-015-4150-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/06/2015] [Indexed: 12/23/2022]
Abstract
RATIONALE Compulsive symptoms develop in patients exposed to pramipexole (PPX), a dopaminergic agonist with high selectivity for the D3 receptor. Consistently, we demonstrated that PPX produces an exaggerated increase in contrafreeloading (CFL) for water, a repetitive and highly inflexible behavior that models core aspects of compulsive disorders. OBJECTIVES Given the role of the hippocampus in behavioral flexibility, motivational control, and visuospatial working memory, we investigated the role of hippocampus in the expression of PPX-induced CFL. To this aim, rats were subjected to CFL under chronic PPX, and then examined for the electrophysiological, structural, and molecular properties of their hippocampus. METHODS We measured long-term potentiation (LTP) at CA1 Schaffer collaterals, dendritic spine density in CA1 pyramidal neurons, and then glutamate release and expression of pre and postsynaptic proteins in hippocampal synaptosomes. The effects of PPX on hippocampal-dependent working memory were assessed through the novel object recognition (NOR) test. RESULTS We found that PPX-treated rats showing CFL exhibited a significant decrease in hippocampal LTP and failed to exhibit the expected increase in hippocampal spine density. Glutamate release and PSD-95 expression were decreased, while pSYN expression was increased in hippocampal synaptosomes of PPX-treated rats showing CFL. Despite a general impairment of hippocampal synaptic function, working memory was unaffected by PPX treatment. CONCLUSIONS Our findings demonstrate that chronic PPX affects synaptic function in the hippocampus, an area that is critically involved in the expression of flexible, goal-centered behaviors. We suggest that the hippocampus is a promising target in the pharmacotherapy of compulsive disorders.
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Affiliation(s)
- Chiara Schepisi
- Department of Physiology and Pharmacology, Sapienza University, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | | | - Salvatore Simone Doronzio
- Department of Physiology and Pharmacology, Sapienza University, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | | | | | - Silvia Di Prisco
- Department of Pharmacy, Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
| | | | - Anna Pittaluga
- Department of Pharmacy, Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
| | | | - Martine Ammassari-Teule
- IRCCS Santa Lucia, Rome, Italy
- Institute of Cell Biology and Neurobiology, National Research Council, Rome, Italy
| | - Robert Nisticò
- Department of Physiology and Pharmacology, Sapienza University, Piazzale Aldo Moro 5, 00185, Rome, Italy
- European Brain Research Institute, Rome, Italy
| | - Paolo Nencini
- Department of Physiology and Pharmacology, Sapienza University, Piazzale Aldo Moro 5, 00185, Rome, Italy
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Differences in the structure of drinking, cart expression and dopamine turnover between polydipsic and non polydipsic rats in the quinpirole model of psychotic polydipsia. Psychopharmacology (Berl) 2014; 231:3889-97. [PMID: 24647922 DOI: 10.1007/s00213-014-3527-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 02/26/2014] [Indexed: 12/19/2022]
Abstract
RATIONALE Dopaminergic D2/D3 agonist quinpirole (QNP) elicits nonregulatory drinking in rats, a model of psychotic polydipsia. Why only a fraction of QNP-treated rats responds to the treatment becoming polydipsic is still unclear. OBJECTIVES To unveil possible factors contributing to such variability, we analyzed drinking microstructure in saline and QNP-treated rats, the hypothalamic expression of the cocaine and amphetamine regulated transcript (CART), and the monoaminergic turnover in selected brain areas. METHODS Rats were daily treated with saline or QNP 0.5 mg/kg, and their 5-h water intake was measured for five consecutive days. The number of bouts and episodes of licking, and their duration, were also measured. Brain CART expression was measured by in situ hybridization and monoamines turnover by HPLC analysis of tissue extracts. Based on the amount of water ingested during the 5-h session, QNP-treated rats were post hoc grouped in polydipsic (PD) and in nonpolydipsic (NPD) rats, and the results compared accordingly. RESULTS The number of drinking bouts and episodes increased in PD rats, while NPD rats behaved as the controls. CART expression decreased in the arcuate nucleus of the hypothalamus of the PD rats. In contrast, both PD and NPD rats showed a reduction of DA turnover in both ventral tegmental area (VTA) and nucleus accumbens (NAcc). No difference was detected in the turnover of 5HT and NA. CONCLUSIONS Microstructure analysis confirms that QNP acts on the appetitive component of drinking behavior, making it compulsive. CART expression reduction in response to dopaminergic hyperstimulation might sustain excessive drinking in PD rats.
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Abstract
Obsessive-compulsive disorder (OCD) and related conditions (trichotillomania, pathological skin-picking, pathological nail-biting) are common and disabling. Current treatment approaches fail to help a significant proportion of patients. Multiple tiers of evidence link these conditions with underlying dysregulation of particular cortico-subcortical circuitry and monoamine systems, which represent targets for treatment. Animal models designed to capture aspects of these conditions are critical for several reasons. First, they help in furthering our understanding of neuroanatomical and neurochemical underpinnings of the obsessive-compulsive (OC) spectrum. Second, they help to account for the brain mechanisms by which existing treatments (pharmacotherapy, psychotherapy, deep brain stimulation) exert their beneficial effects on patients. Third, they inform the search for novel treatments. This article provides a critique of key animal models for selected OC spectrum disorders, beginning with initial work relating to anxiety, but moving on to recent developments in domains of genetic, pharmacological, cognitive, and ethological models. We find that there is a burgeoning literature in these areas with important ramifications, which are considered, along with salient future lines of research.
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Effects of the 5HT2C antagonist SB242084 on the pramipexole-induced potentiation of water contrafreeloading, a putative animal model of compulsive behavior. Psychopharmacology (Berl) 2013; 227:55-66. [PMID: 23241649 DOI: 10.1007/s00213-012-2938-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 11/26/2012] [Indexed: 01/07/2023]
Abstract
RATIONALE In rats, quinpirole, a dopaminergic D2/D3 receptor agonist, elicits both hyperdipsia and water "contrafreeloading" (CFL), a putative model of compulsivity. The role of D3 receptors in this effect remains unclear. Clomipramine (CIM) was found to contrast both hyperdipsia and CFL, but the role of serotonin in this effect requires further investigation. OBJECTIVES We studied the effects of the preferential D3 agonist pramipexole (PPX) in both models. Furthermore, we tested the sensitivity of PPX-induced CFL to CIM and to the 5HT2c antagonist SB242084. METHODS In experiment 1, drinking was measured at 2 and 5 h after eight daily injections of PPX (0 to 1.0 mg/kg intraperitoneally). In the CFL study, every other third lever press, the rat was reinforced by the delivery of water. On days 1-6, water was only available upon lever pressing. On days 7-15, choice between response-contingent and free access was provided. PPX doses as in the experiment 1 were given. In two further experiments, PPX (0.5 mg/kg) was administered alone or in combination with CIM (5 or 10 mg/kg) or SB242084 (0.3 or 1.0 mg/kg). RESULTS PPX did not produce hyperdipsia but enhanced spontaneous CFL. SB242084 attenuated PPX-induced CFL more effectively than CIM, restoring the preference for free access to water. CONCLUSIONS CFL, but not polydipsia, was induced by preferential D3 activation, an effect prevented by 5HT2c receptor blockade. Since PPX interferes with decision making and 5HT2c receptor supersensitivity is involved in the expression of compulsive behaviors, this study supports the compulsive nature of dopaminergic-induced CFL.
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Amato D, Müller CP, Badiani A. Increased drinking after intra-striatal injection of the dopamine D2/D3 receptor agonist quinpirole in the rat. Psychopharmacology (Berl) 2012; 223:457-63. [PMID: 22581392 DOI: 10.1007/s00213-012-2735-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 04/24/2012] [Indexed: 11/29/2022]
Abstract
RATIONALE Dopamine D2 receptor hyperactivity has been implicated in the development of psychogenic polydipsia in schizophrenic patients. Repeated treatment with dopamine agonists, including the D2/D3 agonist quinpirole, has been shown to induce hyperdipsia in a number of animal models. Despite these observations, obtained with systemic administrations, little attempt has been made to investigate where in the brain dopamine agonists act to induce hyperdipsia. OBJECTIVE The present study investigates the effects of repeated intra-caudate infusions of quinpirole on the intake of water by rats tested under free-drinking conditions. MATERIALS AND METHODS Rats with bilateral cannulae placed into the anterior, central or posterior caudate received quinpirole microinfusions (1 μg/side) for five consecutive days in their home cage. Water intake was measured 15 and 60 min after the treatment. RESULTS When injected in the central caudate, quinpirole increased water intake, and this effect progressively increased over sessions, indicating the development of sensitization. When injected in the posterior caudate, the dipsogenic effect of quinpirole was less intense and did not undergo sensitization. The infusion of quinpirole in the anterior caudate did not affect drinking. CONCLUSION The present study shows that caudate D2/3 receptors play an important role in the development of quinpirole-induced hyperdipsia, an animal model of psychotic polydipsia.
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Affiliation(s)
- Davide Amato
- Section of Addiction Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University Erlangen-Nuremberg, 91054 Erlangen, Germany.
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Clomipramine, but not haloperidol or aripiprazole, inhibits quinpirole-induced water contrafreeloading, a putative animal model of compulsive behavior. Psychopharmacology (Berl) 2011; 218:749-59. [PMID: 21660444 DOI: 10.1007/s00213-011-2372-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/24/2011] [Indexed: 10/18/2022]
Abstract
RATIONALE Repeated administrations of the D2/D3 agonist quinpirole (QNP) to rats elicit an antieconomical pattern of drinking called "contrafreeloading" (CFL), a putative model of compulsive-like behavior. OBJECTIVES We tested the sensitivity of QNP-induced CFL to haloperidol (HAL), aripiprazole (ARI), and clomipramine (CIM), the latter proven effective in the treatment of obsessive-compulsive disorder (OCD). METHODS Rats were trained under a schedule of reinforcement (FR3) for water. On days 1-6, water was only available through lever pressing. On days 7-15, a choice between operant and free access was provided. QNP 0.5 mg/kg was administered alone or in combination with HAL (0.1 or 0.2 mg/kg), ARI (0.3 or 1 mg/kg), or CIM (5 or 10 mg/kg). RESULTS Acutely QNP suppressed operant behavior and, therefore, water intake; upon repeated administrations, tolerance developed to this suppressant effect on responding but only to a lesser extent to the antidipsic effect. In choice conditions, QNP induced a progressive preference for the operant access (CFL). HAL per se, but not CIM and ARI, significantly reduced both responding and drinking (operant phase). In the choice phase, HAL and CIM inhibited CFL, but only the latter reinstated total water intake. ARI, in combination with QNP, increased responding. CONCLUSIONS CIM reinstates control patterns of drinking, while HAL and ARI where partially or not effective at all, respectively. As far as CIM is considered a first line treatment in OCD, these results further strengthen the notion that QNP-induced CFL belongs to the realm of dopaminergic drug-induced compulsive behaviors.
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Milella MS, Passarelli F, De Carolis L, Schepisi C, Nativio P, Scaccianoce S, Nencini P. Opposite roles of dopamine and orexin in quinpirole-induced excessive drinking: a rat model of psychotic polydipsia. Psychopharmacology (Berl) 2010; 211:355-66. [PMID: 20552172 DOI: 10.1007/s00213-010-1909-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Accepted: 06/03/2010] [Indexed: 02/05/2023]
Abstract
RATIONALE Repeated administration of the dopamine D2/D3 agonist quinpirole (QNP) progressively increases non-regulatory water intake. This effect may model psychotic polydipsia, a potentially fatal but poorly understood condition. OBJECTIVES The growing evidence for a role of orexin in mediating arousal and cognition has linked this peptide to schizophrenia, hence we examined whether manipulations of dopaminergic and orexinergic systems, as well as of setting, would further characterize the model. METHODS Water intake was measured in rats sequentially tested in home and then operant conditioning setting, with chronic administration of D2 antagonist haloperidol (Hal) prior to QNP treatment. A group of rats similarly treated was also assessed for orexin A (OxA) expression in the cortex. Finally, the effect of the orexin-1 receptor antagonist SB-334867 on QNP-induced polydipsia was evaluated. RESULTS In rats made polydipsic by QNP the amount of water drank during the first 4 h was strongly correlated with the degree of dissociation between appetitive and consummatory components of drinking behavior in the following hour of operant access to water. Hal 0.2 mg/kg prevented both polydipsia and the dissociation, while 0.1 mg/kg only blocked the dissociation. Chronic QNP treatment increased, in a Hal-reversible way, OxA expression in the somatosensory cortex (SI). Moreover, pretreatment with SB-334867 sped up and potentiated QNP-induced polydipsia. CONCLUSIONS Results disclose compulsive components in QNP-induced polydipsia that are mediated by dopamine D2 receptors. QNP also regulates OxA expression in the SI, while the block of orexin-1 receptors enhances QNP-induced polydipsia. We suggest that dopamine and OxA play opposite roles in QNP-induced polydipsia.
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Affiliation(s)
- Michele S Milella
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, 5 Piazzale Aldo Moro, 00185 Rome, Italy
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Amato D, Stasi MA, Borsini F, Nencini P. Haloperidol both prevents and reverses quinpirole-induced nonregulatory water intake, a putative animal model of psychogenic polydipsia. Psychopharmacology (Berl) 2008; 200:157-65. [PMID: 18597076 DOI: 10.1007/s00213-008-1229-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 06/03/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE Polydipsia is a severe complication of long-term schizophrenia and, despite its unknown pathogenesis, is empirically treated with typical or atypical antipsychotics. In the rat, nonregulatory water intake is induced by repeated administration of amphetamine-like compounds or by the D2/3 agonist, quinpirole. OBJECTIVE This study is aimed at determining the potential activity of antipsychotic compounds with different affinities for D2 receptors in preventing and/or reversing quinpirole-induced polydipsia. MATERIALS AND METHODS Male Sprague-Dawley rats were treated with five injections of quinpirole (0.5 mg/kg i.p.) to induce polydipsia. The oral effects of haloperidol, olanzapine, clozapine, and ST2472 on QNP-induced polydipsia were analyzed in the following two schedules. In the preventive schedule, haloperidol (0.2, 0.4, and 0.8 mg/kg), olanzapine (1.5, 3, and 6 mg/kg), ST2472 (1 and 2 mg/kg), and clomipramine (5, 10, and 20 mg/kg) were given in combination with quinpirole from day 1 to day 5. In the reversal schedule, rats showing quinpirole-induced polydipsia on the third day received haloperidol (0.4 mg/kg), olanzapine (1.5 and 3 mg/kg), clozapine (10, 20, and 40 mg/kg), ST2472 (1, 2, 5, and 10 mg/kg), and clomipramine (5, 10, and 20 mg/kg) before quinpirole on days 4 and 5. RESULTS Haloperidol both prevented and reversed quinpirole-induced polydipsia, whereas olanzapine and ST2472 only reversed it. Clomipramine prevented but did not reverse quinpirole-induced polydipsia, and clozapine did not reverse it either. CONCLUSIONS We suggest that, once developed, polydipsia is governed by dopaminergic D2 mechanisms. In contrast, either an increase in the serotoninergic tone or an inhibition of D2 receptors can modulate the development of quinpirole-induced excessive drinking.
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Affiliation(s)
- Davide Amato
- Department of Human Physiology and Pharmacology "Vittorio Erspamer", University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185, Rome, Italy
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