Sustained effects of repeated restraint stress on muscle and adipocyte metabolism in high-fat-fed rats

Repeated restraint stress 3 h/day for 3 days in rats causes a temporary hyp ophagia but a sustained weight loss. We investigated whether poststress cha nges in peripheral tissue metabolism contributed to these responses. One da y after the last restraint, insulin sensitivity, measured by oral glucose t olerance test, was improved in restrained rats. Restraint and pair-fed rats weighed less than controls, but body fat content was the same in all group s. Muscle glucose uptake, measured in vitro, was not changed by treatment, whereas in vitro adipocyte glucose uptake was substantially inhibited only in restrained rats. Adipocytes from restrained rats had elevated rates of f atty acid oxidation but not fatty acid esterification, indicating a shift i n energy supply from glucose to fatty acids. Five days after the last restr aint, the reduced weight of restrained and pair-fed rats resulted from loss of both lean and fat tissue. These results demonstrate that restraint caus ed sustained, tissue-specific changes in metabolism that may contribute to changes in body composition and body weight of the rats.