P.7.b.003 Autoantibodies directed against melanocortin peptides are associated with feeding and anxiety in rats

Abstract

Alpha-melanocyte stimulating hormone (α-MSH) reduces food intake in birds and mammals. The objective of this experiment was to determine effects of α-MSH on food and water intake, and hypothalamic c-Fos immunoreactivity and appetite-associated factor mRNA in Japanese quail (Coturnix japonica), a species that has not undergone the same artificial selection for growth-related traits as the chicken. At 7 days post-hatch, 3-h-fasted quail were intracerebroventricularly (ICV) injected into the lateral ventricle with 0 (vehicle), 0.5, 5, or 50 pmol of α-MSH and food and water intake were recorded at 30 min intervals for 180 min. In the second and third experiment, quail were injected with 50 pmol α-MSH and hypothalami were collected at 1 h to determine c-Fos immunoreactivity and mRNA abundance, respectively. At 30 min, quail injected with 5 or 50 pmol of α-MSH ate and drank less than vehicle-injected quail. Quail injected with 50 pmol ate less for the entire duration of the experiment and drank less than vehicle-injected quail for 120 min post-injection. Hypothalamic expression of agouti-related peptide and DOPA decarboxylase were greater in vehicle- than α-MSH-injected quail, whereas melanocortin receptor 4 (MC4R) mRNA was greater in α-MSH- than vehicle-injected birds. Alpha-MSH injection was associated with more c-Fos immunoreactive cells in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN) of the hypothalamus. Results suggest that the anorexigenic effect of α-MSH is conserved among avians and that effects in quail are associated with the VMH and PVN and involve MC4R.