Stress-induced inhibition of triglyceride secretion in vivo in sand rats (Psammomys obesus)

The effects of acute stress upon circulating triglyceride, glucose, insulin, free fatty acids, and glycerol were investigated in obese desert sand rats. Three groups of animals, designated "nonstress," "nonexertional stress," and "exertional stress," were studied. Acute stress, with or without accompanying exercise, was associated with significant decreases in circulating triglyceride; significant increases in circulating glucose, free fatty acids, and glycerol; and variable changes in circulating insulin. Since these data indicated that substrate availability and hepatic insulization were adequate and therefore could not explain the observed fall in circulating triglyceride, endogenous triglyceride secretion rates were examined by the Triton method. Compared to predicted rates based upon earlier studies, both nonexertional and exertional stress were associated with significantly decreased endogenous triglyceride secretion. Thus, acute stress in the sand rat, with or without accompanying exercise, appears to induce an immediate decrease in endogenous triglyceride secretion and circulating triglyceride.