Exercise-induced hyperphagia in the hamster is associated with elevated plasma somatostatin-like immunoreactivity

Syrian golden hamsters when allowed free access to food and an exercise wheel will run long distances and develop hyperphagia and accelerated linear body growth with high circulating levels of growth hormone and insulin. Somatostatin, a widely distributed brain-gut neurohormonal peptide, modulates nutrient absorption and may regulate food intake. To examine the role of circulating plasma somatostatin-like immunoreactivity (SRIF-LI; pg/ml) in exercise induced hyperphagia 4 groups of animals were studied; an unrestricted exercise group (279.0 +/- 107.7, n = 10); a sedentary group (121.1 +/- 40.8, n = 8); a restricted exercise group (107.7 +/- 12.4, n = 6); and a restricted no exercise group (115.5 +/- 45.9, n = 9). Thus, the unrestricted exercise group has a significantly elevated SRIF-LI concentration (P less than 0.01) while there was no difference between the other 3 groups. The elevation of plasma SRIF-LI in the unrestricted exercise group may represent a response to modulate increased nutrient entry in this group or may represent an incompletely effective satiety signal.