Accumulation of cyclic AMP in hypothyroidism. Decreased sensitivity to norepinephrine in rat adipocytes

The effect of hypothyroidism on the noradrenaline-induced accumulation of 3H-cyclic-AMP was measured in rat epididymal adipose tissue. Adipocytes from hypothyroid animals showed a decreased response to noradrenaline 0.02-0.2 times 10-5 m, while higher concentrations of the catecholamine seemed to elicit the same response in cells obtained from euthyroid or hypothyroid animals. The diminished sensitivity to noradrenaline was unaltered after the addition of phentolamine. It is suggested that thyroid hormones modulate the catecholamine-induced lipolytic response at least partly through the adenyl cyclase cyclic-AMP system.