Cs. Mantzoros et al., SHORT-TERM HYPERTHYROIDISM HAS NO EFFECT ON LEPTIN LEVELS IN MAN, The Journal of clinical endocrinology and metabolism, 82(2), 1997, pp. 497-499
Leptin, a 16-kDa adipocyte-derived protein whose circulating levels re
flect energy stores, increases the resting metabolic rate and thermoge
nesis in rodents. Thyroid hormones also increase the basal metabolic r
ate, but nothing is known about possible interactions between leptin a
nd thyroid hormone. Activation of beta-adrenergic receptors decreases
leptin levels in rodents. To test the hypothesis that thyroid hormones
, by causing a ''functional hyperadrenergic'' state, result in decreas
ed leptin concentrations in humans, we studied 22 normal healthy men b
efore and after the administration of T-3 for 1 week to induce moderat
e hyperthyroidism. Short term thyroid hormone excess does not alter ci
rculating leptin concentrations despite a demonstrated effect on heart
rate, systolic blood pressure, cholesterol levels, and metabolic inde
xes of bone turnover. Elucidation of the apparently separate pathways
by which thyroid hormones, beta-agonists, and leptin regulate energy e
xpenditure and food intake may have important implications for our und
erstanding of the mechanisms for regulating energy homeostasis in heal
th and disease.