The effects of fasting and re-feeding on growth and glucose metabolism and the neuroendocrine control of appetite in the tilapia, oreochromis mossambicus _x000D_/by Rosemary Raso Luzania.

Food deprivation is a common occurrence in the wild and organisms must be able to maintain energy homeostasis during this period. Energy stores, as well as food intake signaling become disrupted during prolonged fasting. Plasma IGF-1 decreased but no changes were observed in liver or muscle IGF-1 mRNA levels. Liver and muscle GHR2 mRNA levels represented a similar trend found in other fish species and may be an indicator that GH resistance is occurring. HSI and liver glycogen levels were reduced, whereas plasma glucose remained unchanged and may suggest an increased lipolysis. Fasting had a greater effect in the telencephalon than in the diencephalon, with increases in GHSR-LR and NPY mRNA levels. Plasma ghrelin was unaffected by fasting, but stomach ghrelin mRNA was reduced and may be due to a slower plasma ghrelin clearance rate in tilapia. Two weeks of re-feeding reversed fasting s effects on growth and glucose metabolism, except for liver glycogen where it appears glycogen stores increased but not enough to match control values. Re-feeding posed similar results for appetite regulating factors. The only change occurring in the diencephalon resulted from re-feeding. hn-GHS-R-LR mRNA levels were decreased during re-feeding and may be due to hn-GHS-R-LR shorter turnover rate than receptor subtypes 1a and 1b. These data provide a further understanding of the mechanisms regulating growth, glucose metabolism, and appetite regulating hormones in tilapia