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.