Meeting Abstract

S10.6  Tuesday, Jan. 6  The Circadian Control of Neuroendocrine and Ovulatory Function: Lessons From the Young and Old KRIEGSFELD, L.J.*; GIBSON, E.M.; WILLIAMS, W.P.; BENTLEY, G.E.; TSUTSUI, K.; University of California, Berkeley; University of California, Berkeley; University of California, Berkeley; University of California, Berkeley; Waseda University kriegsfeld@berkeley.edu

To allow organisms to anticipate daily environmental change and synchronize their activities accordingly, individuals have evolved an endogenous timekeeping mechanism called the circadian clock. The brain clock resides in the suprachiasmatic nucleus (SCN) in the anterior hypothalamus. The requirement for precision in the temporal coordination of behavioral, neural and hormonal events is readily apparent for female reproduction. In hamsters (Mesocricetus auratus), for example, the preovulatory luteinizing hormone (LH) surge required for ovulation occurs at a specific time of day and is stimulated by the timed activation of the reproductive axis by the circadian system. Additionally, the hormonal events associated with ovulation coordinate sexual motivation and receptivity with the time of maximal fertility. The research to be presented uses the rodent ovulatory cycle as a model system for exploring the neural circuits and neurochemical mediators contributing to hormonal timing. In our research, two key neuropeptides in the RFamide family, RFamide-related peptide (RFRP) and kisspeptin, have emerged as key mediators in the circadian control of the ovulatory cycle. Additionally, because reproductive senescence associated with advanced age results, in part, from deficits in clock function, we have begun to use the aging female to further explore the role of the circadian system in reproductive control. Results will be discussed in the context of the importance of hormonal timing for the maintenance of normal health and reproductive functioning.