Effects of apomorphine on rat behavior in the elevated plus-maze. 2005

Andrea Milena Becerra Garcia, and Raquel Martinez, and Marcus Lira Brandão, and Silvio Morato
Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto-USP, Av Bandeirantes 3900, 14049-901 Ribeirão Preto-SP, Brasil.

It has been reported that novelty may evoke both an exploratory and a fear drive, thus generating behavior responding to an approach/avoidance conflict. However, not much is known about the approach component. Whereas there exists abundant evidence referring to the avoidance component as the main target for the anxiolytic action of benzodiazepines, the involvement of dopaminergic mechanisms in fear and anxiety is controversial. The present study examined the effects of the dopaminergic agonist apomorphine, the D(2) dopaminergic antagonist sulpiride and the combined treatment sulpiride plus apomorphine on conventional and non-conventional measures of the behavior of rats exposed to an elevated plus-maze. Systemic injection of apomorphine (0.25, 0.5 and 1.0 mg/kg) caused a selective increase in the time spent in the open arms and in the open arm extremities. Pre-treatment with sulpiride blocked these effects while this dopaminergic antagonist had no effect by its own. Apomorphine produced no significant effects on stretching, flat-back-approach or scanning. Therefore, apomorphine increased the behavioral response linked to the approach component of the conflict without affecting risk assessment behaviors. These findings suggest that dopaminergic mechanisms, probably through D(2) receptors, may also be involved in the mediation of the conflict derived from the need of gathering information for confirming, identifying and localizing danger and take the appropriate action for avoiding the threatening stimuli of the elevated plus-maze. A role for dopaminergic mechanisms in the setting up of adaptive responses in a fear-inducing environment is discussed.

UI MeSH Term Description Entries
D008297 Male Males
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D000704 Analysis of Variance A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable. ANOVA,Analysis, Variance,Variance Analysis,Analyses, Variance,Variance Analyses
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001058 Apomorphine A derivative of morphine that is a dopamine D2 agonist. It is a powerful emetic and has been used for that effect in acute poisoning. It has also been used in the diagnosis and treatment of parkinsonism, but its adverse effects limit its use. Apokinon,Apomorphin-Teclapharm,Apomorphine Chloride,Apomorphine Hydrochloride,Apomorphine Hydrochloride Anhydrous,Apomorphine Hydrochloride, Anhydrous,Apomorphine Hydrochloride, Hemihydrate,Britaject,Apomorphin Teclapharm
D001522 Behavior, Animal The observable response an animal makes to any situation. Autotomy Animal,Animal Behavior,Animal Behaviors
D013469 Sulpiride A dopamine D2-receptor antagonist. It has been used therapeutically as an antidepressant, antipsychotic, and as a digestive aid. (From Merck Index, 11th ed) Aiglonyl,Arminol,Deponerton,Desisulpid,Digton,Dogmatil,Dolmatil,Eglonyl,Ekilid,Guastil,Lebopride,Meresa,Pontiride,Psicocen,Sulp,Sulperide,Sulpitil,Sulpivert,Sulpor,Synédil,Tepavil,Vertigo-Meresa,neogama,vertigo-neogama,Vertigo Meresa,vertigo neogama
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor
D017208 Rats, Wistar A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain. Wistar Rat,Rat, Wistar,Wistar Rats
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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