Acute exogenous TSH administration stimulates leptin secretion in vivo

Abstract

TSH-receptor (TSHR) has been found in a variety of cell types, including preadipocytes and adipocytes.In vitro, TSH-mediated preadipocyte and adipocyte responses include proliferation, differentiation, survival, and lipolysis.ObjectiveTo measure the response of serum leptin to exogenous administration of recombinant human TSH (rhTSH)in vivo.PatientsOne hundred patients with differentiated thyroid cancer already treated by total thyroidectomy and131I remnant ablation were enrolled. Mean (±s.e.m.) body mass index (BMI) was 26.9±0.6 kg/m2.MethodsPatients received a standard dose of rhTSH for measurement of thyroglobulin in the follow-up of their disease. Blood samples were taken for the assay of TSH and leptin before the first administration of rhTSH (time 0), and 24 h (time 1), 48 h (time 2), 72 h (time 3), and 96 h (time 4) after the first administration of rhTSH.ResultsSignificant mean serum leptin increments, with respect to basal value, were 16, 13, 18, and 11% at times 1, 2, 3, and 4 respectively. Significant positive correlations of leptin–area under the curve with respect to basal leptin levels (r=0.43;P<0.0001) and BMI (r=0.32;P<0.005) were observed.ConclusionsAcute rhTSH administration in hypothyroid subjects underl-thyroxine therapy produces a rise in serum leptin. This increase is proportional to the adipose mass suggesting that a functioning TSHR is expressed on the surface of adipocytes. The role that TSHR activation in adipocytes might play in physiological and pathological conditions remains a matter of investigation.