HCG

HCG Overview

Human Chorionic Gonadotropin (HCG) is a specialized glycoprotein hormone categorized as a gonadotropin. It consists of two distinct protein subunits: the alpha subunit, which is common to other hormones like luteinizing hormone (LH) and thyroid-stimulating hormone (TSH), and the beta subunit, which provides HCG with its specific biological characteristics. In research settings, HCG is primarily recognized for its ability to mimic LH by binding to the LH/chorionic gonadotropin receptor (LHCGR). This binding triggers essential intracellular signaling pathways, specifically the cAMP-dependent pathway, which regulates the production of steroid hormones in the gonads.

Historically and scientifically, HCG is notable for its extended biological half-life, which is significantly longer than that of endogenous LH. This property allows for a more sustained hormonal effect in laboratory models. While its primary natural role is supporting the corpus luteum and progesterone synthesis during early pregnancy, researchers utilize HCG to study various endocrine responses, including follicular maturation in female models and the stimulation of testosterone in Leydig cells within male models.

HCG Structure

The molecular architecture of HCG is defined by its complex heterodimeric protein chains and its heavy glycosylation, which protects the molecule from rapid degradation.

Specification Parameter

Technical Detail

Full Identification

Human Chorionic Gonadotropin (HCG)

Molecular Composition

Heterodimeric Glycoprotein

Approximate Mass

36,700 Daltons

Alpha Chain Mass

10,205 Daltons

Beta Chain Mass

15,547 Daltons

Chemical Abstract Number

9002-61-3

Protein Sequence

237 Total Amino Acid Residues

Structure Solution Formula:

The empirical molecular formula for the HCG protein backbone is C1105H1770N318O336S26. This plain-text formula represents the carbon, hydrogen, nitrogen, oxygen, and sulfur atoms that form the primary amino acid sequence of the alpha and beta subunits combined.

HCG Research

HCG and Reproductive Regulation

HCG is a critical tool in the study of female reproductive cycles. By acting as an LH analog, it is used to induce the final maturation of the ovarian follicle and trigger oocyte release. Research demonstrates that HCG supports the development and maintenance of the corpus luteum, which is essential for the secretion of progesterone. These mechanisms are frequently explored in studies focusing on assisted reproductive technologies and the optimization of luteal-phase support.

HCG and Androgen Modulation

In male endocrinology, HCG research focuses on its direct action on the testes. By interacting with the LHCGR on Leydig cells, HCG facilitates the synthesis of testosterone. This is particularly relevant in research models where natural gonadotropin production is inhibited. Studies have shown that HCG can preserve intratesticular testosterone and support the process of spermatogenesis, making it a key subject in the investigation of male fertility and hormone replacement therapies.

HCG and Metabolic Observations

The relationship between HCG and weight management has been the subject of intensive scientific scrutiny. Despite various dietary protocols involving HCG, controlled clinical trials have concluded that the hormone itself does not possess weight-reducing or fat-burning properties. Most researchers agree that weight loss observed in these scenarios is the result of severe caloric restriction, and HCG does not appear to influence fat distribution or metabolic rate in a significant manner.

HCG and Endocrine Markers

HCG is also investigated for its cross-reactivity with thyroid receptors due to its similarity to TSH. High levels of the hormone can lead to mild thyroid stimulation, a phenomenon studied in both pregnancy and certain pathological conditions. Furthermore, HCG serves as a reliable biomarker in oncology research, as elevated levels can indicate the presence of specific trophoblastic or germ cell tumors, aiding in the study of diagnostic monitoring and tumor progression.

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 renowned 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, contributing to the refinement of controlled ovarian stimulation protocols. Alongside collaborators such as B. Alsbjerg, A.D. Coviello, W.J. Bremner, B.J. Schoenfeld, and R. Ramasamy, his work has advanced understanding of gonadotropin regulation, testosterone synthesis, and endocrine modulation in both male and female models. Dr. Humaidan’s contributions continue to inform research in reproductive endocrinology, hormone regulation, and clinical infertility management.

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.

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.

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.

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.

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.

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.

ClinicalTrials.gov. Efficacy and Safety of Long Term Use of hCG or hCG Plus hMG in Males With Isolated Hypogonadotropic Hypogonadism (IHH). (Tongji Hospital study NCT03687606).

STORAGE

Storage Instructions

Our HCG products are manufactured using a high-purity lyophilization process. This freeze-drying method removes moisture and stabilizes the peptide, allowing it to remain viable during shipping for 3 to 4 months at ambient temperatures. After the product is reconstituted with a liquid medium like bacteriostatic water, it becomes much more sensitive. It must be stored in a refrigerator (2 to 8 degrees Celsius) and should be used within 30 days to ensure maximum experimental accuracy.

Best Practices For Storing Peptides

Maintaining the stability of your peptides requires strict adherence to storage protocols:

• Initial Receipt: Upon delivery, immediately store the lyophilized powder in a cool, dark place. For short-term needs, a standard refrigerator is sufficient.
• Long-Term Protection: For storage lasting several months or years, use a freezer set to -80 degrees Celsius. This deep-freeze environment prevents the slow degradation of the protein subunits.
• Handling Temperature Changes: Avoid "frost-free" freezers, as their temperature cycles can damage the peptide's integrity. When removing a vial from cold storage, let it sit at room temperature before opening to prevent moisture condensation.
• Aliquot Strategy: To protect your stock, divide the total peptide volume into several smaller vials (aliquots). This ensures that only the material needed for a single session is exposed to light and air.

Storing Peptides In Solution

Peptide solutions are highly susceptible to degradation and bacterial contamination. If you must store HCG in liquid form, use a sterile buffer with a pH of 5.0 to 6.0. These solutions should never be stored at room temperature for more than a few hours. Keep them refrigerated and use them promptly. If a solution must be frozen, avoid multiple freeze-thaw cycles, as this can break the non-covalent bonds between the alpha and beta subunits.

Peptide Storage Containers

Use only high-quality glass or chemically resistant plastic vials (polypropylene). Glass is generally preferred for its inert properties. Ensure the vials are tightly sealed to minimize the amount of oxygen that can interact with the peptide, as oxidation can alter the function of specific amino acids like cysteine or methionine.

Peptide Storage Guidelines: General Tips

• Keep the peptide in a cold, dry, and dark environment at all times.
• Do not subject the product to repeated freeze-thaw cycles.
• Minimize the amount of air inside the storage vial to prevent oxidation.
• Protect the product from any direct exposure to light.
• Always prioritize storage in the dry, lyophilized state.