Participação da leptina na modulação de eventos aversivos

• Ano de defesa: 2014
• Autor(a) principal: Carla Junia Santos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Óxido nítrico; Ansiedade; Leptina; Teste de lamber punido de Vogel; Labirinto em cruz elevado; Oxído nítrico; Fisiologia
• Link de acesso: http://hdl.handle.net/1843/BUOS-9MAHNF

Leptin is an adypokine secreted mainly by adypocites and plays a pivotal role in metabolism homeostasis and body weight. It reaches the central nervous system via a saturable transport system through the blood-brain barrier. The leptin receptors are expressed mainly in hypothalamus, however they are also present in brain regions related to anxiety and depression related behaviors, such as, prefrontal cortex, amygdala and hippocampus suggesting that leptin could also be involved in stress related responses. Several neurotransmitters may be involved in the control of mood disorders, including nitric oxide (NO). Moreover, leptin may be related with NO production. However, the role of this peptide on behavioral consequences related to stressful events is poorly understood. Thus, the aim of this study was verify the role of leptin in two animal models of anxiety, the elevated plus maze and Vogel Conflict test. We also verified if the leptin effect on anxiety-response were due NO inhibition. Our results showed that the injection of 10 g/1L significantly increased the percentage of entries in the open arms as compared to vehicle group, suggesting an anxiolytic-like effect. No effects were observed in the number of entries into the enclosed arms, suggesting that its effects were not related to impairment in locomotion. Moreover, leptin also induced anxiolytic-like effects in the VCT, observed by a significantly increase in the number of punished licks. These effects were not related with water consumption or nociceptive threshold, discarding potential confounding factors for the Vogel conflict test. The leptin effects in the EPM test were prevented by L-arginine, suggesting that its effects were related to NO inhibition. In conclusion, our results showed that i.c.v. injections of leptin induced anxiolytic-like effects in two different animal models of anxiety, suggesting that this peptide could also modulate anxiety-related responses, possibly trough inhibiton of NO synthesis.