Role of neuropeptide Y and galanin in high altitude induced anorexia in rats.

Anorexia causing weight loss at high altitude (HA) is a major problem. Neuropeptide Y (NPY) and galanin are considered to have appetite regulatory function. The present study was therefore undertaken to investigate the changes in these two peptides at simulated HA and its possible role in anorexia. Male Sprague-Dawley rats (n = 8 in each group) were exposed to simulated HA (7620 m) for 1, 7, 14 and 21 days for 6 h a day and to an altitude of 6,096 m for 72 h to study the effect of intermittent and continuous exposure, respectively. NPY and galanin levels were estimated in different brain parts and plasma of exposed and unexposed control animals. Significant reduction in food intake was observed in rats during both intermittent as well as continuous exposure. In case of 72 h continuous exposure severe reduction in food intake was observed (73.2%) with reduction in body mass (approximately 29.7g/rat in 48h). Hypothalamic NPY levels were decreased by 54.7, 35.0 and 15.4% in 1, 7, and 14 days, respectively, in case of intermittent exposure to HA. However in case of 72 h HA exposure no significant change in hypothalamic and circulating NPY levels were observed. Plasma galanin levels were decreased in both intermittent and 72 h continuous HA exposed rats. Hypothalamic galanin levels were also decreased in 72h exposed rats. The changes in levels of these peptides may be responsible for anorexia at HA.