HCG

Human chorionic gonadotropin (hCG) is a glycoprotein hormone consisting of alpha and beta subunits. The alpha subunit is shared with LH, FSH, and TSH; the beta subunit is unique to hCG and confers receptor specificity. hCG binds the LH/hCG receptor (LHCGR) with higher affinity and a much longer half-life than LH itself, making it the pharmacological equivalent of LH in research contexts where sustained receptor stimulation is needed.

In reproductive biology, hCG's endogenous role is pregnancy maintenance -- it is produced by trophoblast cells after implantation and signals to the corpus luteum to maintain progesterone production during early pregnancy. Its presence in urine forms the basis of pregnancy tests. In research and clinical endocrinology, hCG is used to trigger ovulation (mimicking the LH surge), stimulate testosterone production in men with secondary hypogonadism, assess Leydig cell function, and induce testicular descent in cryptorchidism.

For research involving the male HPG axis, hCG provides an LH agonist effect: it directly stimulates Leydig cells to produce testosterone without requiring pituitary LH secretion. This makes it useful for studying testosterone production independently of pituitary-hypothalamic function, and for maintaining testicular function during research protocols that suppress LH (such as GnRH agonist or antagonist studies).

Specifications

Storage

Store at 2-8°C (refrigerator). As a glycoprotein, hCG should not be frozen repeatedly -- store lyophilized form refrigerated, not frozen. After reconstitution, use within 28 days at 2-8°C. Do not shake; gently swirl to dissolve.

HCG is supplied for laboratory research use only. Not approved for unsanctioned human use. Handle in compliance with institutional biosafety guidelines.