Defective trophic response of brown adipose tissue of myopathic hamsters

Hamsters with muscular dystrophy (BIO 14.6) have a smaller than normal amount of brown adipose tissue. Two stimuli that promote growth of brown adipose tissue in normal hamsters, short photoperiod and eating a high-fat diet, are here shown to be without effect on brown adipose tissue of myopathic hamsters. Cold-induced growth of brown adipose tissue occurs normally [Am. J. Physiol. 239 (Cell Physiol. 8): C18-C22, 1980]. There is a normal rate of turnover of norepinephrine in brown adipose tissue of the myopathic hamster but a failure of the tissue to hypertrophy in response to norepinephrine is unlikely since norepinephrine does not appear to mediate the trophic response [Am. J. Physiol. 247 (Endocrinol. Metab. 10): E793-E799, 1984]. Denervation results in a marked reduction in size (protein content) of brown adipose tissue of normal hamsters but has very little effect on the size of brown adipose tissue of myopathic hamsters. A central, possibly hypothalamic, defect in the myopathic hamster is postulated to underlie its abnormal control of brown adipose tissue hypertrophy.