Meeting Abstract

87.9  Thursday, Jan. 7  NPY and GnRH Systems Respond to Food Deprivation in a Mouthbrooding Cichlid GRONE, B.P.*; LEE, M.; FERNALD, R.D.; Stanford University bgrone@stanford.edu

Astatotilapia burtoni, a mouthbrooding cichlid native to Lake Tanganyika, is a model organism used for studying reproductive physiology and behavior. After females become gravid and spawn, they carry their developing fry in their mouths for two weeks before releasing them. During these two weeks, females do not feed and they experience significant metabolic changes. Females also experience metabolic changes as they recover from mouthbrooding and become gravid again. In order to understand how the brain responds to the food-deprivation experience during mouthbrooding, we have compared the effects of mouthbrooding- and non-mouthbrooding-related food deprivation on neuropeptide systems involved in feeding and reproduction. We used quantitative RT-PCR to measure levels of Neuropeptide Y (NPY) Receptors and Gonadotropin-Releasing Hormone (GnRH) mRNA in the A. burtoni brain. A. burtoni express three GnRHs: GnRH1, GnRH2, and GnRH3. Only GnRH1 was regulated by mouthbrooding: mouthbrooding females’ brains had significantly lower GnRH1 than gravid females’. By contrast, food deprivation significantly decreased GnRH1, GnRH2, and GnRH3 mRNA levels in the brain. NPY is the most potent orexigenic neuropeptide in teleosts. Teleosts have two closely related NPY Receptor Y8 (NPYR Y8) forms: Y8a and Y8b. We found that food-deprived A. burtoni have significantly more NPYR Y8b mRNA in their brains than fed animals do. Levels of NPYR Y8c were not different between fed and food-deprived groups. Our findings suggest involvement of Y8b but not Y8c in response to food deprivation. Overall, we describe reproductive and orexigenic neuroendocrine profiles that distinguish simple food deprivation from the food-deprived reproductive state of mouthbrooding.