Norepinephrine does not alter NPY and POMC mRNA expression in neonatal chicks

Abstract

Norepinephrine (NE), synthesized in both the central and peripheral nervous system, is involved in food intake regulation of both mammals and chickens. Neuropeptide Y (NPY), a potent orexigenic peptide, is colocalized with NE neurons in the central and peripheral nervous system, suggesting an interaction. Proopiomelanocortin (POMC) is the precursor of α-melanocyte stimulating hormone, a potent anorexigenic peptide synthesized in the hypothalamus. In this study, two experiments were conducted to examine the effect of intracerebroventricular (ICV) injection of NE on appetite mediators in neonatal chicks ( Gallus gallus). Experiment 1 was done to confirm the effect of centrally administered NE (0, 25, 50, and 100 μg) on food intake following a 3 h fast, and to determine the change in NPY mRNA expression in the central nervous system (CNS). In Experiment 2, chicks fed ad libitum were treated ICV with NE (50 μg) to determine if changes occurred in brain NPY and POMC mRNA levels. In Experiment 1, the ICV injection of NE dose-dependently reduced food intake, but there was no change in NPY mRNA expression in the CNS. In Experiment 2, there was no significant change in NPY and POMC mRNA expression between the control and NE-treated group, indicating that ICV injection of NE may not be associated with changes in NPY or POMC gene expression.