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STEPHEN J. WINTERS, PHILIP TROEN, α-Subunit Secretion in Men With Idiopathic Hypogonadotropic Hypogonadism, The Journal of Clinical Endocrinology & Metabolism, Volume 66, Issue 2, 1 February 1988, Pages 338–342, https://doi.org/10.1210/jcem-66-2-338
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Abstract
We studied the regulation of glycoprotein hormone α-subunit secretion in four men with idiopathic hypogonadotropic hypogonadism due to presumed GnRH deficiency. Immunoreactive α-subunit was present at low but usually detectable levels in blood samples drawn at 10- to 20-min intervals for 12–24 h; however, no characteristic pattern of pulsatile asubunit secretion was found. Serum from each man was examined by gel filtration chromatography. Each sample tested contained an immunoreactive α-subunit peak with a slightly lower elution volume than [125I]hCGα, as we had previously found in serum from normal men. To determine if this peak represented TSHα, two men were treated with 0.3 mg l-T4 daily for 7-14 days. Serum TSH levels decreased to less than 1.5 mU/L, and neither TSH nor α-subunit levels increased after the iv administration of 500 μg TRH. An α-subunit peak that eluted before [125I]hCGα was again found in the serum of T4-treated men. We conclude that glycoprotein hormone α-subunit is present in the serum of men with idiopathic hypogonadotropic hypogonadism in whom TSH secretion is completely suppressed by l-T4. The gonadotrophs represent the most likely source of this α-subunit. The finding of more normal α-subunit than LH secretion in these men indicates that the production of the gonadotropin subunits is differentially regulated in man and supports the hypothesis that factors in addition to GnRH regulate α-subunit gene expression.
