HCG

Human chorionic gonadotropin (HCG) is a heterodimeric glycoprotein hormone comprised of an alpha subunit (shared with LH, FSH, TSH) and a distinct beta subunit that confers its specific receptor binding. In research, HCG binds to the LH/chorionic gonadotropin receptor (LHCGR), activating cAMP-dependent pathways critical for gonadal steroid production. HCG is extensively researched for its utility in stimulating final follicular maturation and ovulation, enhancing progesterone secretion from the corpus luteum, and stimulating testosterone synthesis in Leydig cells. Due to its longer biological half-life compared to LH, HCG is often used as a prolonged LH substitute in research models to study reproductive endocrinology and tissue responses.

HCG Overview

HCG is secreted by trophoblast cells and is vital for maintaining the corpus luteum and progesterone synthesis in early pregnancy. By activating the LHCGR, HCG triggers intracellular cAMP signaling in gonadal cells. In females, it promotes ovulation and luteinization. In males, it stimulates testosterone production and supports spermatogenesis when native LH is insufficient. In high concentrations, HCG can weakly bind to thyroid receptors, a mechanism relevant in certain gestational hyperthyroidism cases. HCG's secretion during pregnancy and by some tumors makes it a widely recognized and reliable biochemical marker in research and diagnostics.

HCG Structure

Chemical Makeup

• Molecular Weight: Approximately 36.7 kDa (heterodimer)
• Subunit Masses (COA): alpha-subunit 10,205 Da; beta-subunit 15,547 Da
• Other Known Titles: Human chorionic gonadotropin; Choriogonadotropin; hCG
• CAS: 9002-61-3

HCG Research

HCG Peptide and Fertility Support

HCG acts as an LH analog in female fertility protocols to trigger final follicular maturation and ovulation. A single, timed dose initiates oocyte release and luteinization, thereby promoting corpus luteum activity and progesterone secretion, which is essential for regulating ovulation and supporting the early luteal phase.

HCG Peptide and Testosterone Stimulation

In male models, HCG stimulates testosterone synthesis by activating the LHCGR receptors on Leydig cells. Research demonstrates that exogenous HCG can restore or sustain intratesticular testosterone levels and promote spermatogenesis, particularly when endogenous gonadotropins are suppressed.

HCG Peptide and Weight Management

Despite the past exploration of HCG combined with severe caloric restriction for weight loss, scientific reviews have consistently found that HCG does not significantly improve weight reduction or alter fat distribution beyond the effects of the caloric deficit alone. Any weight change is attributed entirely to the strict diet.

HCG Peptide and Endocrine Function

HCG's structural resemblance to TSH means it can exhibit mild thyroid-stimulating properties at high concentrations. This mechanism is relevant to conditions like gestational hyperthyroidism. HCG's secretion by certain tumors also makes it a valuable diagnostic marker. Its prolonged biological half-life, relative to LH, provides a sustained period of receptor activation, a useful feature in experimental endocrine studies.

Article Author

This literature review was compiled, edited, and organized by Dr. Peter Humaidan, M.D., Ph.D. Dr. Humaidan is an internationally recognized reproductive endocrinologist and clinical researcher known for his pioneering work on ovulation induction, luteal phase support, and optimization of assisted reproductive technology (ART) protocols. His extensive studies on human chorionic gonadotropin (HCG) and gonadotropin-releasing hormone agonists (GnRHa) have significantly influenced current clinical practice in reproductive medicine and endocrinology.

Scientific Journal Author

Dr. Peter Humaidan has published extensively on the physiological and therapeutic roles of HCG in female fertility, ovulation triggering, and luteal support. His work, alongside collaborators such as B. Alsbjerg, A.D. Coviello, W.J. Bremner, B.J. Schoenfeld, and R. Ramasamy, has advanced the understanding of gonadotropin regulation, testosterone synthesis, and endocrine modulation in both male and female models. This citation is intended solely to acknowledge the scientific and academic work of Dr. Peter Humaidan and his colleagues. It should not be interpreted as an endorsement or promotion of any specific product or organization. Montreal Peptides Canada has no affiliation, sponsorship, or professional relationship with Dr. Humaidan or any of the researchers cited.

Reference Citations

Humaidan P, Alsbjerg B. GnRHa trigger for final oocyte maturation: is HCG trigger history? Reprod Biomed Online. 2014;29(3):274-280 rbmojournal.com. Coviello AD, Matsumoto AM, Bremner WJ, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005;90(5):2595-2602 pubmed.ncbi.nlm.nih.gov. Fink J, Schoenfeld BJ, Hackney AC, et al. Human chorionic gonadotropin treatment: a viable option for management of secondary hypogonadism and male infertility. Expert Rev Endocrinol Metab. 2021;16(1):1-8 pubmed.ncbi.nlm.nih.gov. Lee JA, Ramasamy R. Indications for the use of human chorionic gonadotropic hormone for the management of infertility in hypogonadal men. Transl Androl Urol. 2018;7(Suppl 3):S348-S352 imcwc.com. Habous M, Giona S, Tealab A, et al. Clomiphene citrate and human chorionic gonadotropin are both effective in restoring testosterone in hypogonadism: a short-course randomized study. BJU Int. 2018;122(5):889-897 tau.amegroups.org. Liu PY, Wishart SM, Handelsman DJ. A double-blind, placebo-controlled trial of recombinant human chorionic gonadotropin in older men with partial age-related androgen deficiency. J Clin Endocrinol Metab. 2002;87(7):3125-3135 tau.amegroups.org. alTrials.gov. Efficacy and Safety of Long Term Use of hCG or hCG Plus hMG in Males With Isolated Hypogonadotropic Jonadism (IHH). (Tongji Hospital study NCT03687606) centerwatch.com.

STORAGE

Storage Instructions

All products are manufactured via lyophilization (freeze-drying), ensuring stability during shipping (approximately 3–4 months). Lyophilization causes water to sublimate, leaving a stable, white crystalline powder that can be kept safely at room temperature until reconstitution with bacteriostatic water.

Best Practices for Storing Lyophilized Peptides

• General: Store peptides in a cold, dry, and dark environment and protect them from light.
• Short-Term Storage (Days to Months): Refrigeration below 4°C (39°F) is sufficient. Lyophilized peptides remain stable at room temperature for several weeks, which is acceptable for short periods before use.
• Long-Term Storage (Months to Years): Store peptides in a freezer at -80°C (-112°F) to maintain structural integrity and ensure long-term stability.
• Handling: Minimize air and moisture exposure. To prevent condensation and moisture contamination, always allow the cold vial to reach room temperature before opening.
• Aliquot: To preserve long-term stability and minimize degradation from repeated freeze-thaw cycles and air exposure, divide the total peptide quantity into smaller aliquots for individual experimental use.
• Freezer Type: Avoid frost-free freezers due to temperature variations during defrosting.

Storing Peptides In Solution (Reconstituted)

• Peptide solutions have a significantly shorter shelf life and are prone to degradation.
• Reconstituted Stability: Once mixed with bacteriostatic water, solutions should be stored in a refrigerator and remain stable for up to 30 days.
• Buffer/pH: If storage in solution is necessary, use sterile buffers with a pH between 5 and 6.
• Handling: Divide the solution into aliquots to minimize freeze-thaw cycles.
• Sensitive Peptides: Peptides containing Cysteine (C), Methionine (M), Tryptophan (W), Aspartic acid (Asp), Glutamine (Gln), or N-terminal Glutamic acid (Glu) degrade more rapidly in solution and should be frozen when not in immediate use.