Authors : Jun-Ichi Shiraishi, Kouchi Yanagita, Hiromi Terao, Maki Matsuura and Takashi Bungo
Abstract: Recent research has revealed the anorexigenic effects of insulin in the central nervous system associated with changes in the expression of hypothalamic neuropeptides such as neuropeptide Y or α-melanocyte stimulating hormone. However, it is possible that monoaminergic system also participates in insulin-induced anorexia in chicks as suggested in early studies which show that changes in monoamine content play important roles in anorexia in mammals. To clarify the role of monoaminergic systems in the anorexic effect of central insulin in neonatal chicks, the levels of brain monoamines after intracerebroventricular injection of insulin were investigated. Although, there were no differences in the levels of adrenalin, 4-hydroxy-3-methoxyphenylacetic acid, serotonin and 5-dihydroxyindole-3-acetic acid at each time point (p>0.1) and the level of noradorenaline in chicks treated with insulin were significantly lower than that with saline at 30 min post-injection (p<0.05). Conversely, dopamine and its metabolite, DOPAC were significantly increased in chicks treated with insulin when compared with the saline control (p<0.01). However, co-injection of dopamine receptor antagonist prolonged insulin-induced anorexia at 60 and 120 min post injection (p<0.05). These results indicate that the central noradrenalinergic but not dopaminergic and serotonergic systems may partly be involved in insulin-induced anorexia in neonatal chicks.
Jun-Ichi Shiraishi, Kouchi Yanagita, Hiromi Terao, Maki Matsuura and Takashi Bungo, 2010. Involvement of the Central Monoaminergic System in Insulin-Induced Anorexia in Chicks. Journal of Animal and Veterinary Advances, 9: 2109-2112.