HCG

Overview

Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone composed of two non-covalently associated subunits: an alpha subunit (92 amino acids) shared with LH, FSH, and TSH, and a unique beta subunit (145 amino acids) that confers biological specificity. Naturally produced by trophoblast cells during pregnancy, HCG has been a cornerstone of reproductive biology research for decades.

HCG's structural and functional similarity to luteinizing hormone (LH) — sharing the same alpha subunit and binding to the same receptor — makes it an invaluable research tool for studying gonadal function, steroidogenesis, and the hypothalamic-pituitary-gonadal (HPG) axis.

Chemical Profile

Mechanism of Action

HCG mimics the action of luteinizing hormone by binding to the LH/CG receptor (LHCGR), a G protein-coupled receptor expressed on Leydig cells in the testes and theca/granulosa cells in the ovaries. Receptor activation triggers the Gs/adenylyl cyclase/cAMP/PKA signaling cascade.

In Leydig cells, this pathway activates steroidogenic acute regulatory protein (StAR), which facilitates cholesterol transport into mitochondria — the rate-limiting step in steroid hormone synthesis. Subsequent enzymatic conversion produces testosterone and other androgens.

In ovarian cells, HCG/LH receptor activation triggers the final maturation of ovarian follicles and the luteinization process that converts follicular cells into the corpus luteum, which produces progesterone essential for pregnancy maintenance.

Research Applications

• LH receptor agonism and signaling
• Gonadal function and steroidogenesis
• Leydig cell stimulation and testosterone production
• Ovulation research and follicular development
• Pregnancy-related hormone studies
• HPG axis modulation
• Reproductive endocrinology models

Handling & Reconstitution

1. 1Allow the vial and sterile water to reach room temperature (15–25°C).
2. 2Using a sterile syringe, withdraw the appropriate volume of sterile water.
3. 3Inject the water slowly along the inside wall of the vial — do not spray directly onto the powder.
4. 4Gently swirl the vial until the powder is fully dissolved. Do not shake vigorously.
5. 5Once reconstituted, store at 2°C – 8°C. Protect from light.
6. 6Use within 28 days after reconstitution.
7. 7Do not freeze reconstituted solution.