Meeting Abstract

87.11  Thursday, Jan. 7  The effects of fasting and re-feeding on the neuroendocrine control of appetite in tilapia, Oreochromis mossambicus LUZANIA, R.R.*; UPTON, K.R.; EARLEY, R.L.; RILEY, L.G.; California State University, Fresno; California State University, Fresno; University of Alabama; California State University, Fresno rluz123@csufresno.edu

Appetite is coordinated primarily in the hypothalamus which integrates orexigenic and anorexigenic signals from the brain and peripheral signals (i.e. metabolic and hormonal). Ghrelin – a novel gut peptide – stimulates appetite in both mammals and fish: its orexigenic actions are mediated by stimulating neuropeptide Y (NPY)-containing neurons in the hypothalamus. Lack of adequate food resources is a constant environmental challenge faced by fish. In spite of this knowledge, our understanding of the hormonal control of appetite during fasting and re-feeding in fish is limited. The current study investigated the effect of fasting and re-feeding on the neuroendocrine control of appetite in the tilapia (Oreochromis mossambicus). Tilapia were subjected to three treatments: fasting for 30 days; fasting for 21 days and re-fed for 9 days; and fed for 30 days (control). Fasting resulted in a significant reduction in growth. Re-feeding reversed the negative effects of fasting on growth. Brain ghrelin mRNA levels were significantly reduced by fasting. Re-feeding for 9 days elevated brain ghrelin mRNA levels, but these levels were not significantly different from either control or fasted fish. Fasting for 30 days did not alter brain mRNA levels of NPY or the ghrelin receptor (GHS-R1a). These data suggest that tilapia are well adapted to a 30 day fast, since NPY mRNA levels (possibly NPY activity) were unaltered by a 30 day fast. Further, our data suggest that brain derived ghrelin may be functioning as a metabolic signal and not as an orexigen. This work was supported by the NSF (IOS-0639771) awarded to LGR.