Meeting Abstract

132.2  Monday, Jan. 7  The Effects of Chronic Cortisol on Appetite in Tilapia Oreochromis mossambicus BRASCHAYKO, E.B.*; RILEY, L.G.; Fresno State Univ.; Fresno State Univ. ebrasch45@mail.fresnostate.edu

Stress in fish has been shown to impair growth, reproduction, immune function and overall health. Stress is managed along the hypothalamic-pituitary-interrenal axis resulting in the release of cortisol. In the brain, appetite regulating hormones include ghrelin, neuropeptide Y (NPY) which both stimulate appetite and corticotropin releasing hormone (CRH) which acts to decrease appetite. Cortisol has been shown to decrease food intake and growth in several species of fish. Whether cortisol is altering the neuroendocrine regulators of food intake is poorly understood in fish. The current study was designed to investigate the effect of chronic cortisol treatment on food intake and the endocrine regulators of appetite in tilapia. Tilapia were fed one of the following treatments: 0 mg/kg (control), 50 mg/kg, and 500 mg/kg cortisol-laden feed. For 32 days fish were fed a known amount of excess feed twice a day, at 0900 and 1600h, and allowed to feed for 1h at which point remaining food was collected to determine food consumption. At 32 days fish were sacrificed and brain and stomach were collected. The high cortisol dose significantly reduced food intake and growth compared to controls. In both the telencephalon and hypothalamus regions of the brain, there was a significant decrease in NPY expression in both the low and high cortisol dose treated fish compared to controls. Interestingly, there was no change in ghrelin expression in the hypothalamus and stomach but ghrelin expression in the telencephalon was significantly decreased in the low cortisol dose. There was no change in CRH levels across treatments in the telencephalon or hypothalamus regions. These data suggest that chronic exposure to cortisol may decrease appetite by decreasing expression of appetite stimulating hormones in the brain.