HCG

Human Chorionic Gonadotropin (HCG) is a heterodimeric glycoprotein hormone composed of a 92-amino acid alpha subunit (shared with LH, FSH, and TSH) and a unique 145-amino acid beta subunit that confers its biological specificity. HCG mimics luteinizing hormone (LH) by binding to the LH/CG receptor (LHCGR), a G-protein coupled receptor expressed on Leydig cells, granulosa cells, and other tissues. In research applications, HCG is used to study gonadal steroidogenesis (testosterone production via the StAR protein and cholesterol side-chain cleavage enzyme cascade), Leydig cell biology and intratesticular testosterone maintenance, ovulation induction and corpus luteum support models, endocrine axis regulation including HPG axis feedback mechanisms, pregnancy physiology and trophoblast biology, and the role of HCG in immune tolerance during pregnancy. The 5000 IU format is standard for research protocols studying dose-dependent steroidogenic responses and sustained gonadal stimulation.