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Key-pecking and treadle-pressing behavior were maintained in five pigeons by a mult. FI5 key FI5 treadle schedule of food presentation. Dose-effect curves for apomorphine and amphetamine on overall rates of responding in both F1 componenets of the multiple schedule were determined. Effective doses of apomorphine caused dose-dependent decreases on treadle-pressing rates in all animals. Similarly, key pecking rates were decreased by increasing doses of apomorphine in two of the five pigeons. However, dose-dependent increases in key-pecking rates were caused by apomorphine in the other three birds. In this group of pigeons, the mean key-pecking rate was increased to over 500% of the control rate by the dose of 1 mg/kg of apomorphine. Observation of the animals under the effect of apomorphine showed continuous pecking at the operative key in these three animals while the other two pecked at different places of the floor and walls of the experimental chamber. Appropriate doses of amphetamine caused rate-increasing effects on key-pecking as well as treadle-pressing rates of all pigeons. These results suggest that the increases in key-pecking rate caused by apomorphine in some pigeons in a conventional operant situation due to the orientation of the drug-induced stereotyped pecking toward the response keypecking, as a consequence of the topographic compatibility between this behavioral effect of apomorphine and the operant selected for study.

original RESUMO Introdução.A obesidade pode ser considerada um dos principais problemas de saúde pública mundial, com números alarmantes ao redor do mundo e correlação com diversas doenças de curso fatal. Fatores ambientais e vários sistemas fisiológicos estão implicados na causa da doença. Um destes sistemas, o de recompensa alimentar que envolve o neurotransmissor dopamina, é amplamente conhecido na literatura como responsável pela motivação à busca de recompensas naturais (alimentos) e artificiais (drogas). Objetivo. Levantar dados na literatura que comprovem o envolvimento da dopamina com a hiperfagia e obesidade. Método. Foi realizada pesquisa em três bases de dados (MedLine, Lilacs e SciELO) com descritores e termos livres relacionados ao assunto, no período de maio/2013 a março/2014. Resultado. Foram encontrados 391 artigos. Após seleção criteriosa, com base nos critérios de exclusão definidos para este trabalho, apenas 17 artigos foram selecionados para discussão, os quais foram unânimes em apontar mudanças no sistema dopaminérgico em participantes obesos, como alterações na liberação de dopamina e na expressão de seus receptores. Conclusão. Futuros estudos precisam explorar mais esta condição através de desenhos experimentais adequados, seguindo o CONSORT, com grupos-controle e resultados validados internacionalmente, na expectativa de controlar os índices de morbi-mortalidade decorrentes deste transtorno alimentar. Unitermos. Obesidade, Dopamina, Receptores DopaminérgicosCitação. Santos AFS, Souza CSV, Oliveira LS, Freitas MFL. Influência da dopamina e seus receptores na gênese da obesidade: revisão sistemática. ABSTRACTIntroduction. Obesity can be considered as a major global public health problem, with alarming numbers worldwide and correlation with several fatal diseases. Environmental factors, as well as various physiological systems are implicated in the cause of the disease. One of these systems, the one of the food reward involving the neurotransmitter dopamine is widely known in the literature as being responsible for motivating the search for natural rewards (food) and artificial rewards (drugs). Objective. To collect data in the literature showing the involvement of dopamine with hyperphagia and obesity. Method. A survey was conducted in three databases (MedLine, Lilacs and Sci-ELO) with descriptors and free terms related to the subject, from May 2013 to March 2014. Results. 391 articles were found. After careful selection, based on exclusion criteria defined for this study, only 17 articles were selected for discussion. In all selected articles, changes in the dopaminergic system in obese participants were observed, including changes in dopamine release and expression of its receptors. Conclusion. Future studies need to further explore this condition through appropriate experimental designs with control groups, following the CONSORT and results validated internationally, to control the morbidity and mortality indices associated to this nutritional disorder.