Food availability as a cue for seasonal reproduction Effect of juvenile food restriction on adult seasonality in Siberian hamsters

Meeting Abstract

P1-115  Sunday, Jan. 4 15:30  Food availability as a cue for seasonal reproduction: Effect of juvenile food restriction on adult seasonality in Siberian hamsters BAILEY, A.M.*; HALL, C.A.; DEMAS, G.E.; Indiana University; Univ. of North Carolina, Pembroke; Indiana University

Seasonally breeding animals respond to multiple environmental cues to determine optimal conditions for reproduction. Siberian hamsters (Phodopus sungorus) primarily rely on photoperiod as a predictive cue of future energy availability; when raised in long-day (LD) photoperiods, supplemental cues such as food availability do not trigger seasonal reproductive responses. Two RFamide neuropeptides, kisspeptin and RFamide-related peptide (RFRP) are hypothesized to function as integrators of environmental signals to coordinate seasonal reproduction. This study investigates whether a nutritional challenge during development subsequently results in altered adult seasonal responses, specifically whether LD adults recognize food availability as a relevant signal after this challenge, and whether this is caused by differential development and activation of kisspeptin and RFRP. Male and female hamsters were given either ad libitum food or 70% of ad lib. intake from weaning until 60 days of age. For five weeks after day 60, all hamsters received ad lib. food to provide a signal of abundant energy reserves. Then, hamsters were again assigned either ad lib. food or a mild food restriction of 80% of baseline intake for six weeks. Body mass and reproductive measurements (estrous cycling in females, estimated testis volume in males) were assessed regularly and will be presented. After six weeks, hypothalamic, gonadal, and adipose tissues were collected for analysis of gene expression of RFamide peptides and their receptors using quantitative PCR. Collectively, the results of this study will increase our understanding of the neuroendocrinology of seasonal reproduction in a relevant environmental context.

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