Expression profile of hypothalamic neuropeptides in chicken lines selected for high or low residual feed intake

The R+ and R− chicken lines have been divergently selected for high (R+) or low (R−) residual feed intake. For the same body weight and egg production, the R+ chickens consume 40% more food than their counterparts R− lines. In the present study we sought to determine the hypothalamic expression profile of feeding-related neuropeptides in these lines maintained under fed or food-deprived conditions.In the fed condition, the suppressor of cytokine signaling 3 (SOCS3) was 17-fold lower (P < 0.05) and the ghrelin receptor was 7-fold higher (P < 0.05) in R+ compared to R− chicken lines. The hypothalamic expression of the other studied genes remained unchanged between the two lines. In the fasted state, orexigenic neuropeptide Y and agouti-related peptide were more responsive, with higher significant levels in the R+ compared to R− chickens, while no significant differences were seen for the anorexigenic neuropeptides pro-opiomelanocortin and corticotropin releasing hormone. Interestingly, C-reactive protein, adiponectin receptor 1 and ghrelin receptor gene expression were significantly higher (12-, 2- and 3-folds, respectively), however ghrelin and melanocortin 5 receptor mRNA levels were lower (4- and 2-folds, P = 0.05 and P = 0.03, respectively) in R+ compared to R− animals.We identified several key feeding-related genes that are differently expressed in the hypothalamus of R+ and R− chickens and that might explain the difference in feed intake observed between the two lines.