HCG

Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone naturally produced by placental trophoblast cells during pregnancy, serving as the basis for pregnancy testing. Structurally, it shares an alpha subunit with the pituitary glycoprotein hormones (LH, FSH, TSH), while its unique beta subunit confers HCG-specific biological activity.

HCG's primary mechanism involves activation of the LH receptor (LHCGR), producing LH-like effects with a significantly longer half-life (24-36 hours vs 20-60 minutes for LH). In males, this stimulates testicular Leydig cells to produce testosterone. In females, it supports corpus luteum function and progesterone production during early pregnancy.

Research applications include fertility treatment, where HCG triggers ovulation and supports luteal phase function, and male reproductive studies, where it stimulates endogenous testosterone production without suppressing the hypothalamic-pituitary axis as exogenous testosterone does.

The extended half-life and potent LH receptor activation make HCG valuable for research requiring sustained gonadotropin signaling. Recombinant HCG offers advantages of consistent glycosylation and absence of urinary contaminants, while urinary HCG remains widely used and more affordable for many research applications.