HCG

Why Researchers Study HCG

Human chorionic gonadotropin (HCG) is a glycoprotein gonadotropin that acts as a long-acting analogue of luteinising hormone. Its beta subunit is close enough to LH’s to bind the same receptor, but its carbohydrate structure makes it clear far more slowly, so it produces prolonged LH-like receptor signalling where endogenous LH delivers short pulses. That property makes HCG a reference probe for the gonadal end of the hypothalamic-pituitary-gonadal (HPG) axis.

Where kisspeptin acts at the very top of the axis (hypothalamic GnRH neurons), HCG bypasses the hypothalamus and pituitary entirely and acts directly at the LH/CG receptor on Leydig cells.

Mechanism of Action

HCG binds the LH/CG receptor (LHCGR) on Leydig cells. Receptor activation couples through Gs to adenylyl cyclase, raising cAMP and activating protein kinase A. PKA drives StAR-mediated transport of cholesterol into the mitochondrion, the rate-limiting step of steroidogenesis, followed by enzymatic conversion through pregnenolone toward testosterone.

Research Context

Investigational literature uses HCG as a reference LHCGR agonist in Leydig-cell steroidogenesis and HPG-axis signalling studies. Its long receptor occupancy distinguishes it from LH itself, whose plasma half-life is far shorter.

Storage

Supplied as a lyophilised powder in a 5000 IU vial. Store lyophilised vials refrigerated.

For research purposes only. Not for human consumption.