What Is HCG? Human Chorionic Gonadotropin Explained

HCG (human chorionic gonadotropin) is a glycoprotein hormone composed of an α subunit and a β subunit. It is produced by placental trophoblast cells during pregnancy and is widely studied in reproductive endocrinology research, where it acts on the luteinizing hormone/chorionic gonadotropin receptor (LHCGR). This article is strictly educational and describes physiology and laboratory research only. Bolt Peptide does not sell HCG; nothing here is intended for human use, and any research material would be for research use only (RUO).

Quick facts

• Class: glycoprotein hormone (gonadotropin family)
• Subunits: an α subunit (shared with LH, FSH, and TSH) and a hormone-specific β subunit
• Receptor: luteinizing hormone/chorionic gonadotropin receptor (LHCGR)
• Research focus: reproductive endocrinology and gonadal steroidogenesis

What is HCG?

Human chorionic gonadotropin is a heterodimeric glycoprotein hormone. Like the other gonadotropins, it pairs a common α subunit with a distinct β subunit; the β subunit and its glycosylation give HCG its specificity. In normal human physiology, HCG is secreted by trophoblast cells of the early embryo and placenta, where it helps sustain the corpus luteum’s progesterone output during early pregnancy. Because it shares a receptor with luteinizing hormone (LH) but has a much longer circulating half-life, HCG is sometimes described in the literature as a long-acting LH-like signal. This page discusses that biology purely as a topic of scientific study.

What does the research show?

In reproductive-endocrinology research, HCG and LH bind the same receptor yet are not functionally identical. A comprehensive review in Endocrine Reviews describes how the two hormones display “biased agonism” at the LHCGR: HCG signaling is characterized by a strong cAMP/protein kinase A (PKA) steroidogenic profile, while LH leans more toward kinase pathways associated with cell proliferation [1]. Foundational physiology summaries note that HCG’s long half-life (on the order of ~37 hours, versus minutes for LH) allows sustained receptor stimulation in the relevant tissues [2]. These observations are reported strictly as descriptions of measured physiology and laboratory findings, not as outcomes for any individual.

Mechanisms studied in the lab

• LH/CG receptor signaling: HCG binds the extracellular domain of the LHCGR, a G-protein-coupled receptor that couples primarily to Gαs to activate adenylyl cyclase, cAMP, and PKA, with additional pathway engagement reported at higher hormone/receptor levels [1].
• Gonadal steroidogenesis: in experimental models, LHCGR activation by HCG is associated with downstream steroid-hormone synthesis, including progesterone production in corpus luteal cells [2].

Research status

As a factual matter, HCG is an approved medicine used by clinicians in regulated fertility and endocrine settings. That clinical status is noted here only for context. It does not change the framing of this article: any HCG-related material handled in a laboratory setting would be for research use only (RUO), is not a drug or supplement, and is not intended for human or veterinary use, diagnosis, or treatment. Bolt Peptide does not currently offer HCG.

Related research peptides

If you are exploring hormone-axis and growth-hormone-secretagogue compounds for research, browse the full research peptide catalog. You may also find this educational article useful: What is Sermorelin? covers a growth-hormone-releasing hormone analog studied on the somatotropic axis, providing helpful background for understanding endocrine-signaling research more broadly.

FAQ

Is HCG a peptide or a hormone? HCG is a glycoprotein hormone built from two peptide subunits (α and β) plus attached carbohydrate chains. It is larger and more complex than the short synthetic peptides commonly discussed in research catalogs.

What receptor does HCG act on? It acts on the luteinizing hormone/chorionic gonadotropin receptor (LHCGR), the same receptor that responds to LH.

Does Bolt Peptide sell HCG? No. This article is educational only. We do not currently carry HCG, and nothing here is intended for human use.

References

1. Casarini L, et al. Two Hormones for One Receptor: Evolution, Biochemistry, Actions, and Pathophysiology of LH and hCG. Endocr Rev. 2018.
2. Ogino MH, Tadi P. Physiology, Chorionic Gonadotropin. StatPearls.

For research use only. Not a drug, food, cosmetic, or supplement; not for human or veterinary use. Statements have not been evaluated by the FDA.