Acute exogenous TSH administration stimulates leptin secretion in vivo.
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. Objective To measure the response of serum leptin to exogenous administration of recombinant human TSH (rhTSH) in vivo. Patients One hundred patients with differentiated thyroid cancer already treated by total thyroidectomy and (131)I remnant ablation were enrolled. Mean (+/-s.e.m.) body mass index (BMI) was 26.9+/-0.6 kg/m(2). Methods Patients 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. Results Significant 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. Conclusions Acute rhTSH administration in hypothyroid subjects under l-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.
Santini
Ferruccio
F
Department of Endocrinology and Kidney Dulbecco Telethon Institute at Department of Endocrinology and Kidney University Hospital of Pisa, Via Paradisa, 2, 56124 Pisa, Italy. fsantini@endoc.med.unipi.it
Galli
Giulia
G
Maffei
Margherita
M
Fierabracci
Paola
P
Pelosini
Caterina
C
Marsili
Alessandro
A
Giannetti
Monica
M
Castagna
Maria Grazia
MG
Checchi
Serenella
S
Molinaro
Eleonora
E
Piaggi
Paolo
P
Pacini
Furio
F
Elisei
Rossella
R
Vitti
Paolo
P
Pinchera
Aldo
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011989:Receptors, Thyrotropin / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000097:blood* / Q000188:drug therapy* / Q000601:surgery; D013972:Thyrotropin / Q000627:therapeutic use*; D055815:Young Adult
D020738:Leptin; D011989:Receptors, Thyrotropin; D013972:Thyrotropin