IMMOBILIZATION-INDUCED STRESS DECREASES LIPOGENESIS IN SEBACEOUS GLANDS AS WELL AS PLASMA TESTOSTERONE LEVELS IN MALE SYRIAN-HAMSTERS

The effects of immobilization-induced stress on plasma testosterone levels and lipogenesis in the sebaceous gland were examined in male Syrian hamsters. To induce immobilization stress, the animals were placed in the prone position and wrapped with flexible steel wire gauze at room temperature. Plasma testosterone levels were determined by radioimmunoassay (RIA) of blood samples and sebaceous lipogenesis was determined by measurement of the incorporation of a lipid precursor, C-14-acetate, in ear skin biopsy samples. Both specimens were obtained immediately after the hamsters were decapitated. Immobilization stress for 4 consecutive days produced a marked fall in plasma testosterone levels and sebaceous lipogenesis. These reductions were reversible, the decreased plasma testosterone levels and decreased sebaceous lipogenesis recovering to the nonstressed or prestimulus levels after approximately 1 week. In 4-day stressed animals in occurrence with a decrease in plasma testosterone, sebaceous lipogenesis in ear with topical application of a small dose of testosterone, which have no effect on plasma testosterone level, was equivalent to that in nonstressed animals. These findings indicated that immobilization-induced stress lowered testosterone secretion, and consequently the testosterone levels in the skin, resulting in decreased lipogenesis in the skin. These results thus suggest that psychological or physiological stress can influence cutaneous function by inducing changes in the neuroendocrine system.