Meeting Abstract

87.6  Thursday, Jan. 7  Neuroendocrine Regulation of Decreased Food Intake During Acute Stress in the Tilapia, Oreochromis mossambicus UPTON, K. R.*; RILEY, L.G.; California State Univ., Fresno kelliupton@csufresno.edu

Food intake results from a set of complex neuroendocrine signals that integrate external stimuli with the internal milieu of the animal. Ghrelin – a novel gut hormone – is known to stimulate appetite whose actions are mediated by neuropeptide Y (NPY) in the hypothalamus. Further, the ghrelin receptor (growth hormone secretagogue receptor: GHS-R) has been shown to be located on NPY-containing neurons. In several teleosts species, a decrease in food intake following an acute stress has been observed. However, the neuroendocrine mechanism controlling the reduction in food intake during stress has yet to be determined. This study was designed to investigate the effect of an acute stress on food intake and brain expression of NPY, ghrelin and GHS-R in the tilapia (Oreochromis mossambicus). After a 30 min crowding and handling stress, fish were fed for 1 h after which time food intake was determined. An acute stress significantly reduced food intake when compared to control fish. In a second group of animals, tissue samples were collected immediately following the stressor. Hypothalamic mRNA levels of NPY and ghrelin were significantly reduced, while GHS-R mRNA levels were significantly elevated. Conversely, in the telencephalon-preoptic area NPY, ghrelin and GHS-R mRNA levels were significantly elevated. The results indicate that decreased food intake following an acute stress is mediated by suppressed mRNA levels of NPY and ghrelin in the hypothalamus. Further, our findings suggest that ghrelin and NPY are differentially regulated in different regions of the brain during stress suggesting that these hormones exhibit multiple regulatory functions related to overall metabolism. This work was supported by the National Science Foundation (IOS-0639771) awarded to LGR.