Dieting and weight loss in volunteers increases the number of alpha 2-adrenoceptors and 5-HT receptors on blood platelets without effect on [3H]imipramine binding.

Platelet monoamine receptor binding was determined in normal male and female subjects before and at the end of a 2- to 3-week weight reducing diet (1200 kcal daily). Dieting was associated with an increase in platelet binding sites for both [3H]yohimbine and [125I]iodolysergic acid diethylamide (iodoLSD). The affinity at the platelet [125I]iodoLSD binding site was reduced. In contrast, [3H]imipramine binding was unchanged. These results have important implications for studies that employ platelet binding as a peripheral marker of neurotransmitter function in psychiatric illness.