HMG

What it is: Human Menopausal Gonadotropin (HMG / Menotropins) is a purified biological glycoprotein preparation standardized to contain equal biological activity of Follicle-Stimulating Hormone (FSH, 75 IU) and Luteinizing Hormone (LH, 75 IU). Both hormones are non-covalently linked heterodimers composed of a common 92-amino-acid alpha subunit non-covalently joined to hormone-specific beta subunits that confer specific receptor selectivity.

How it works: Operates through dual, complementary endocrine mechanisms: The FSH fraction binds transmembrane FSH Receptors (FSHR) exclusively expressed on Sertoli cells, elevating intracellular cAMP to drive Androgen-Binding Protein (ABP) secretion, tight-junction maintenance, and the mitotic proliferation of spermatogonia. Concurrently, the LH fraction engages LH/Choriogonadotropin Receptors (LHCGR) on Leydig cells, activating the steroidogenic acute regulatory (StAR) pathway to sustain essential intratesticular testosterone (ITT) microenvironments. In contrast to hCG monotherapy (which activates only LH receptors), HMG provides necessary Sertoli cell stimulation to maintain complete germ cell maturation.

Why researchers study it: Researched extensively in laboratory models of severe hypogonadotropic hypogonadism, reversal of suppressed spermatogenesis following exogenous androgenic saturation, preservation of Sertoli cell cytoarchitecture, and endocrine axis restoration.