title: Insulin-like factor 3: a novel circulating hormone of testicular origin in humans.
abstract: Insulin-like factor 3 (INSL3) affects testicular descent. Mutations in the INSL3 gene or its receptor, LGR8/GREAT, can cause cryptorchidism. Expression of LGR8/GREAT in different tissues and production of INSL3 by adult-type Leydig cells suggest additional roles for this hormonal system in adults. We used a novel radioimmunoassay kit to measure INSL3 concentrations in the serum of normal men and those with different testicular pathologies. We demonstrate that INSL3 circulates in adult men and is almost exclusively of testicular origin. Subjects with severe testicular damage (infertility) produce small amounts of INSL3, and concentrations of this hormone seem to reflect the functional status of the Leydig cells. Analysis of men treated with different combinations of hormones of the hypothalamus-pituitary-testis axis suggests that the production of INSL3 is related to the luteinizing hormone.
authors.affiliation: Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, Centre for Male Gamete Cryopreservation, Via Gabelli 63, 35127 Padua, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ferlin
authors.forename: Carlo
authors.initials: C
authors.lastname: Foresta
mesh_terms: D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D008297:Male; D011506:Proteins / Q000378:metabolism; D011863:Radioimmunoassay; D013737:Testis / Q000378:metabolism*
chemical_list: D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins