AgRP1 modulates breeding season-dependent feeding behavior in female medaka

Feeding and reproduction are known to be closely correlated with each other, and the seasonal breeders show breeding season-dependent feeding behavior. However, most model animals do not have definite breeding seasonality, and the mechanisms for such feeding behavior remain unclear. Here, we focused on female medaka (<i>Oryzias latipes</i>); they show breeding season-dependent feeding behavior, and their condition of breeding season can be experimentally controlled by day-length. We first demonstrated that, among previously reported feeding-related peptides (neuropeptides involved in feeding), agouti-related peptide 1 (<i>agrp1</i>) and neuropeptide y b (<i>npyb</i>) show higher brain expression under the breeding condition than under the non-breeding one. Combined with analysis of <i>agrp1</i> knockout medaka, we obtained results to suggest that long day-induced sexually mature condition, especially ovarian estrogenic signals, increase the expressions of <i>agrp1</i> in the brain, which results in increased food intake to promote reproduction. Our findings advance the understanding of neural mechanisms of feeding behavior for reproductive success.