Fed and fasted chicks from lines divergently selected for low or high body weight have differential hypothalamic appetite-associated factor mRNA expression profiles

Abstract

We have demonstrated that chicken lines which have undergone intense divergent selection for either low (LWS) or high (HWS) body weight (anorexic and obese containing, respectively) have differential food intake threshold responses to a range of intracerebroventricular injected neurotransmitters. The study reported herein was designed to measure endogenous appetite-associated factor mRNA profiles between these lines in an effort to further understand the molecular mechanisms involved in their differential eating patterns. Whole hypothalamus was collected from 5 day-old chicks that had been fasted for 180min or had free access to food. Total RNA was isolated, reverse transcribed, and real-time PCR performed. Although mRNAs encoding orexigenic neuropeptides including agouti-related peptide, neuropeptide Y (NPY), prolactin-releasing peptide, and visfatin did not differ in expression between the lines, NPY receptor 5 mRNA was greater in fed LWS than HWS chicks, but fasting decreased the magnitude of difference. Anorexigenic factors including amylin, corticotropin releasing factor (CRF) and ghrelin were not differentially expressed between lines, while mRNA abundance of calcitonin, CRF receptor 1, leptin receptor, neuropeptide S, melanocortin receptor 3, and oxytocin were greater in LWS than HWS chicks. Pro-opiomelanocortin mRNA was lower in LWS than HWS chicks, while fasting decreased its expression in both lines. These results suggest that there are differences in gene expression of appetite-associated factors between LWS and HWS lines that might be associated with their differential food intake and thus contribute to differences in severity of anorexia, body weight, adiposity, and development of obesity.