HCG (Human Chorionic Gonadotropin) Research Guide — LHCGR Mechanism, Leydig Cell Steroidogenesis & HPG Axis Biology (2026)
- HCG (human chorionic gonadotropin; hCG) is a glycoprotein hormone consisting of two non-covalently associated subunits: a shared α-subunit (identical to LH, FSH, and TSH α-subunits) and a hormone-specific β-subunit that confers LHCGR binding specificity. Naturally produced by placental syncytiotrophoblasts during pregnancy; compound forms are derived from pregnant women’s urine (urinary hCG) or produced by recombinant DNA technology. YPB offers research-grade HCG as YPB.256 in 5,000 IU configuration (Research Use Only).
- Mechanism: HCG binds the LH/CG receptor (LHCGR — the same Gs-coupled GPCR that binds LH) on Leydig cells in the testis and on granulosa/luteal cells in the ovary. LHCGR activation → Gs → adenylyl cyclase → cAMP ↑ → PKA → StAR (steroidogenic acute regulatory protein) phosphorylation → cholesterol transport into mitochondria → CYP11A1-mediated cleavage to pregnenolone → testosterone synthesis cascade. HCG is approximately 10-fold more potent than LH in cAMP recruitment due to additional sialic acid residues on its β-subunit that extend half-life and increase LHCGR occupancy; however, downstream testosterone output per unit receptor activation is equivalent between LH and HCG.
- Research applications: HPG axis biology (Leydig cell steroidogenesis, LH receptor pharmacology); male fertility research (spermatogenesis support, intratesticular testosterone); female fertility research (ovulation induction, corpus luteum function, progesterone support); hypogonadotropic hypogonadism models; pregnancy marker biology. HCG has research-grade compound equivalents (Pregnyl, Novarel) for wellness support; research-grade HCG is not equivalent to any compound preparation.
- WADA context: HCG is prohibited in male athletes by WADA (S2 Peptide Hormones, Growth Factors, Related Substances and Mimetics) because it stimulates endogenous testosterone production via the Leydig cell pathway, potentially masking exogenous androgen use. Not prohibited for female athletes. Research Use Only (RUO). Updated April 2026.
What Is HCG and What Makes It Unique Among Gonadotropins?
~24h Half-Life vs. ~20 min for LH
WADA S2 Prohibited in Males
HCG is the glycoprotein hormone most immediately recognized by the public as the “pregnancy hormone” — it is the analyte detected in urine pregnancy tests and rises sharply in the first trimester of pregnancy. Updated April 2026. Its biological role during pregnancy is to maintain the corpus luteum’s progesterone production beyond the normal luteal phase, preventing menstruation and establishing the hormonal environment for early embryo survival. However, HCG’s pharmacological relevance extends well beyond pregnancy biology: because it binds the same LHCGR receptor as pituitary LH, HCG functions as a surrogate LH signal with dramatically extended half-life, making it one of the most important research tools for studying Leydig cell steroidogenesis, HPG axis biology, and gonadal physiology.
The key pharmacokinetic distinction from LH: endogenous LH is secreted in brief (~20 minute half-life) pulsatile bursts from the pituitary. HCG, by contrast, carries additional sialic acid residues on its β-subunit carbohydrate chains that reduce clearance, extending its half-life to approximately 24 hours. This longer half-life means that a single injection of HCG provides sustained LHCGR stimulation over days — a property that is exploited both in clinical fertility protocols (triggering ovulation at a defined time) and in research settings (providing a sustained Leydig cell steroidogenesis stimulus rather than the short pulsatile LH signal).
Key Characteristics
| Parameter | Value |
|---|---|
| Classification | Glycoprotein hormone; gonadotropin; two-subunit heterodimer |
| Structure | α-subunit (92 AA; identical to LH, FSH, TSH α-subunits; non-covalently associated) + β-subunit (145 AA; unique to HCG; confers LHCGR specificity; 24 AA C-terminal extension vs. LH β-subunit) |
| Molecular Weight | ~36,700 Da (glycoprotein; carbohydrate accounts for ~30% of MW; heavier than conventional synthetic peptides) |
| YPB SKU | YPB.256 — 5,000 IU configuration |
| Receptor | LHCGR (LH/CG receptor; also LHCGR = LH receptor) — the same Gs-coupled class A GPCR that binds LH; expressed on Leydig cells (testis), granulosa/luteal cells (ovary), and multiple extragonadal tissues |
| Signal Transduction | LHCGR → Gs → adenylyl cyclase → cAMP ↑ → PKA → StAR phosphorylation → cholesterol mitochondrial transport → CYP11A1 (cholesterol side-chain cleavage) → pregnenolone → testosterone biosynthesis cascade |
| vs. LH: potency | HCG ~10-fold more potent than LH in in vitro cAMP recruitment (due to additional sialic acid residues); equivalent downstream testosterone synthesis per receptor activation |
| Half-Life | ~24 hours (vs. ~20 minutes for pituitary LH); extended by additional sialic acid residues on HCG β-subunit CTP (C-terminal peptide) reducing renal clearance |
| Source (compound) | Urinary hCG (isolated from urine of pregnant women; Pregnyl, Novarel) or recombinant hCG (CHO cell expression; Ovidrel/choriogonadotropin alfa). Research-grade HCG is not equivalent to any compound preparation. |
| FDA Status | research-grade compound HCG products exist (Pregnyl, Novarel, Ovidrel) for ovulation induction, cryptorchidism. YPB research-grade HCG is RUO only — not equivalent to any compound product. Research Use Only (RUO). |
| WADA Status | Prohibited in males — S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics); prohibited at all times in- and out-of-competition. Not prohibited for female athletes. |
| Storage | Lyophilized: −20°C. Reconstituted: sterile water for injection or bacteriostatic water; 2–8°C, use within 30 days. Glycoprotein: avoid repeated freeze-thaw; do not shake vigorously. |
How Does HCG Work? LHCGR/Gs/cAMP/StAR Steroidogenesis Cascade
LHCGR: The Shared Receptor for LH and HCG
LH (luteinizing hormone) and HCG both bind the LHCGR (LH/chorionic gonadotropin receptor) — a class A G protein-coupled receptor expressed predominantly on Leydig cells in the testis and granulosa/theca/luteal cells in the ovary. The LHCGR is a 699-amino acid GPCR with a large extracellular leucine-rich repeat domain (LRD) that forms the high-affinity binding site for both hormones. HCG binds with slightly higher affinity than LH due to additional carbohydrate chains on its β-subunit, but both ligands activate the same signaling cascade. The additional 24-amino acid C-terminal peptide (CTP) of the HCG β-subunit — absent in LH β — carries O-linked carbohydrate chains with extensive sialylation that dramatically slows renal clearance, explaining the 24-hour vs. 20-minute half-life difference.
cAMP/PKA/StAR: The Steroidogenesis Cascade
LHCGR activation by HCG signals through Gs protein → activates adenylyl cyclase → cAMP production → PKA (protein kinase A) activation. The rate-limiting step in steroidogenesis is the transport of cholesterol from the outer to the inner mitochondrial membrane, where CYP11A1 (cholesterol side-chain cleavage enzyme; P450scc) cleaves the cholesterol side chain to produce pregnenolone. This transport is mediated by StAR (steroidogenic acute regulatory protein), which is phosphorylated and upregulated by PKA. StAR is the primary acute regulator of steroidogenesis — its expression and phosphorylation determine how rapidly Leydig cells can convert cholesterol to pregnenolone. Downstream of pregnenolone: 3β-HSD → progesterone → CYP17A1 (17α-hydroxylase/lyase) → DHEA → androstenedione → 17β-HSD3 → testosterone. In females, the same LHCGR activation in luteal cells drives progesterone synthesis through the same cascade (without the androgenic branch of the pathway dominating).
What Research Applications Has HCG Been Studied For?
HPG Axis and Leydig Cell Steroidogenesis Research
HCG is the primary pharmacological tool for studying Leydig cell steroidogenesis in vitro and in vivo because it provides sustained, controllable LHCGR stimulation without the pulsatile signaling complexity of endogenous LH. Isolated primary Leydig cell cultures or Leydig cell lines (MA-10, MLTC-1) treated with HCG at defined concentrations (1–100 mIU/mL for in vitro dose-response) and timepoints provide the gold-standard model for studying the StAR/cAMP/PKA steroidogenesis pathway, cholesterol transport mechanisms, testosterone biosynthesis gene regulation (StAR, CYP11A1, CYP17A1, HSD3B, HSD17B3), and Leydig cell responses to gonadotropin stimulation and withdrawal.
Male Fertility and Spermatogenesis Research
Spermatogenesis requires intratesticular testosterone concentrations far exceeding serum levels. HCG stimulates Leydig cells to produce this intratesticular testosterone, making it the key tool for studying HCG + FSH combination protocols for spermatogenesis induction in hypogonadotropic hypogonadism models. Published data: combined HCG + FSH therapy induces spermatogenesis in 70–90% of men with hypogonadotropic hypogonadism in clinical settings. In non-obstructive azoospermia (NOA) research, Shiraishi et al. documented that HCG pretreatment (5,000 IU three times in research protocols × 3 months) significantly improved sperm retrieval rates at micro-TESE (21.4% vs. 0% in untreated controls).
Female Fertility and Ovulation Research
In females, HCG’s extended half-life mimics the midcycle LH surge to trigger follicle rupture and ovulation at a predictable time — the basis of its research-grade use in ovulation induction protocols (IVF trigger, clomiphene/letrozole cycles). In the luteal phase, HCG maintains corpus luteum progesterone production beyond the normal 14-day luteal lifespan — the early pregnancy mechanism. Research using HCG in granulosa cell or corpus luteum models studies progesterone synthesis, LH receptor downregulation dynamics, and ovarian steroidogenesis alongside the male Leydig cell pathway.
Pregnancy and Placental Biology Research
HCG is the endogenous glycoprotein produced by placental syncytiotrophoblasts from implantation. Its roles in pregnancy extend beyond corpus luteum maintenance: HCG promotes uterine vascular development, supports immune tolerance of the fetus (modulates maternal NK cell and T-cell responses), and stimulates fetal testosterone production in the second trimester via the fetal Leydig cell pathway. Research using HCG as a tool for studying placental biology, trophoblast differentiation, and the neuroendocrine-immune interface of early pregnancy spans endocrinology, reproductive immunology, and developmental biology.
What Does the Research Data Show?
| Research Area | Model | Key Finding & Notes | Year(s) |
|---|---|---|---|
| LH vs. HCG cAMP/testosterone comparison | In vitro (primary mouse Leydig cells; dose-response) | HCG ~10-fold more potent than LH in cAMP recruitment; no significant difference in downstream testosterone synthesis. Demonstrates spare receptor capacity in Leydig cell steroidogenic pathway. (Reprod Biol Endocrinol, 2017) | 2017 |
| HCG + FSH for hypogonadotropic hypogonadism | Clinical (men with hypogonadotropic hypogonadism) | Combined HCG + FSH therapy induces spermatogenesis in 70–90% of men; HCG alone insufficient for complete spermatogenesis (intratesticular testosterone required; FSH supports Sertoli cells). Established standard for male fertility induction research. | Multiple |
| HCG for NOA/azoospermia | Clinical (48 Japanese research subjects, NOA with failed prior TESE) | HCG 5,000 IU × 3/week × 3–6 months: sperm retrieval at micro-TESE 21.4% vs. 0% in untreated controls (p < 0.05). Significant improvement in Leydig cell function prior to sperm extraction. (Shiraishi et al.; reviewed in Andrology 2025) | 2025 (review) |
| HCG ovulation induction | Clinical (ART/IVF; systematic review) | HCG trigger achieves 15–25% pregnancy rate per cycle in clomiphene/letrozole protocols; higher in gonadotropin stimulation cycles. LH surge equivalent timing confirmed. Standard IVF ovulation triggering research and protocol design tool. | Multiple |
| HCG pharmacokinetics (urinary vs. recombinant) | Clinical (15 healthy eugonadal men; testosterone suppressed; crossover) | 250 µg recombinant hCG equivalent to ~6,500 IU urinary hCG; 62.5 µg recombinant ~equivalent to 1,500 IU urinary hCG. Establishes IU-to-microgram equivalencies for urinary vs. recombinant formulations. (Handelsman et al. 2024, Andrology) | 2024 |
How Does HCG Compare to Other Reproductive Biology Research Compounds?
| Parameter | HCG (YPB.256) | HMG (YPB.258) | Kisspeptin | Triptorelin / GnRH |
|---|---|---|---|---|
| Mechanism | LHCGR agonist (LH mimic); Gs/cAMP/StAR; direct Leydig cell steroidogenesis; ~24h half-life | Contains FSH + LH activities (urinary gonadotropin mixture); dual FSH receptor + LH receptor activation; supports spermatogenesis + steroidogenesis together | Kiss1R/GPR54 agonist; GnRH pulse generator; HPG axis upstream initiator | GnRH receptor agonist; pituitary LH/FSH release; initial stimulation then desensitization at continuous dosing |
| HPG Axis Position | Gonad level: bypasses pituitary; directly activates gonadal LHCGR | Gonad level: bypasses pituitary; directly activates FSH-R and LH-R at gonad | Hypothalamus level: upstream of GnRH; regulates GnRH pulse amplitude and frequency | Pituitary level: stimulates (acute) or suppresses (chronic) pituitary gonadotropin release |
| Primary Research Use | Leydig cell steroidogenesis; testosterone biosynthesis; male fertility; ovulation trigger (female); corpus luteum biology | Spermatogenesis induction + steroidogenesis (paired with HCG); female folliculogenesis support | HPG axis neuroendocrinology; puberty; GnRH pulse biology; fertility triggers | GnRH receptor pharmacology; pituitary desensitization models; prostate cancer research models |
| WADA Status | Prohibited (S2) in males | Prohibited (S2) in males | Not listed | S2 Prohibited (releasing factors) |
| YPB SKU | YPB.256 — see product | YPB.258 — see guide | YPB.276 — see guide | YPB catalog — see guide |
HCG and HMG (human menopausal gonadotropin) form the most direct research pair in reproductive endocrinology: HCG provides the LH signal (Leydig cell testosterone; ovulation trigger); HMG provides both FSH + LH activities (Sertoli cell support for spermatogenesis; folliculogenesis). See the HMG Research Guide for the FSH-containing complementary compound. For upstream HPG axis research, Kisspeptin (see the Kisspeptin Research Guide) operates at the hypothalamic GnRH-pulse level, providing the full gonadotropin axis from hypothalamus to gonad.
What Should Researchers Know About HCG Handling?
Glycoprotein Handling Considerations
HCG is a glycoprotein — not a conventional synthetic peptide — and its handling requires attention to preserving the carbohydrate chains that contribute to both receptor binding and pharmacokinetic extension. Key protocols: reconstitute gently by directing diluent down the vial wall; do not vortex (shaking denatures glycoproteins); use bacteriostatic water (benzyl alcohol preserved) for reconstitution to extend refrigerated shelf life; avoid glass containers at low concentrations (adsorption); do not freeze-thaw after reconstitution — prepare single-use aliquots from lyophilized stock.
IU Measurement: Activity, Not Mass
HCG is measured and sold in International Units (IU) rather than milligrams, reflecting potency standardization by bioassay rather than gravimetric mass. One IU of hCG is defined by the WHO International Reference Preparation. Research protocols should specify IU dosing rather than mass-based concentrations. The 5,000 IU YPB.256 configuration is the standard research vial size for Leydig cell and fertility biology experiments.
Storage
Lyophilized: −20°C for up to 24 months. After reconstitution: 2–8°C, use within 30 days if bacteriostatic water used; within 7 days if plain sterile water used. All YPB HCG batches include lot-traceable COA documentation through the COA Library.
Key Research Findings
- Glycoprotein, not synthetic peptide: α/β heterodimer; ~36,700 Da; carbohydrate ~30% of MW; glycosylation critical for receptor binding and half-life; handle as glycoprotein (no vortex, gentle reconstitution).
- LHCGR Gs/cAMP/PKA/StAR cascade: Same receptor as LH; StAR is rate-limiting step; cholesterol transport into mitochondria → CYP11A1 → pregnenolone → testosterone. StAR phosphorylation by PKA is the primary acute steroidogenesis regulator.
- ~10-fold more potent than LH in cAMP; equivalent testosterone output: Spare receptor capacity in Leydig cells; supraphysiological cAMP does not produce proportionally more testosterone. Research dose design must be on linear portion of dose-response curve.
- ~24h half-life vs. 20 min for LH: Sialic acid residues on HCG β-CTP reduce renal clearance; enables sustained LHCGR stimulation from single injection; ideal for research protocols requiring prolonged gonadotropin exposure.
- WADA S2 Prohibited in males: Stimulates endogenous testosterone via Leydig cells; prohibited because it elevates T:E ratios and may mask exogenous androgen use without leaving exogenous androgen markers.
- HCG + FSH for spermatogenesis: HCG alone provides intratesticular testosterone but FSH required for Sertoli cell support of spermatogenesis; combined HCG + FSH therapy induces sperm production in 70–90% of hypogonadotropic hypogonadism models.
- Research-grade ≠ compound: research-grade HCG products (Pregnyl, Novarel, Ovidrel) are compound-grade. YPB research-grade HCG (YPB.256) is not equivalent and is RUO only.
- IU measurement: Activity-based (WHO reference preparation), not gravimetric mass; use IU dosing in protocols, not mg dosing.
Browse the Full Research Catalog
Market Demand and Research Interest
| Demand Indicator | HCG Data Point |
|---|---|
| PubMed publications | 40,000+ (human chorionic gonadotropin / hCG) |
| Clinical context | research-grade compound use (ovulation induction, cryptorchidism); cornerstone of ART protocols; standard HPG axis research tool across reproductive endocrinology |
| Unique catalog position | Only LHCGR-selective gonadotropin agonist in YPB catalog; only compound providing direct Leydig cell steroidogenesis stimulus (bypasses hypothalamus and pituitary); essential HPG axis biology tool |
| Research communities | Reproductive endocrinology; fertility research; andrology; HPG axis neuroendocrinology; pregnancy biology; anti-doping |
| Disease model relevance | Hypogonadotropic hypogonadism; male infertility; azoospermia; cryptorchidism; female infertility/ART; gestational trophoblastic disease |
| Keyword difficulty range | Medium (KD 20–35); high-volume research audience; well-established compound |
How Can Researchers Offer HCG Under Their Own Brand?
Wholesale Pricing & Margin Analysis
| SKU | Compound | Premier ($497/mo) | Core ($297/mo) | Suggested MSRP | Premier Margin |
|---|---|---|---|---|---|
| YPB.256 (RUO) | HCG (Human Chorionic Gonadotropin) — 5,000 IU | TBC Premier | TBC Core | TBC | TBC at Premier tier |
Contact the YPB team for confirmed Premier and Core tier pricing. Use the YPB Profit Calculator to model projected revenue. White-label brands offering HCG alongside HMG create the complete gonadal hormone research pair: direct Leydig cell testosterone (HCG) plus FSH/LH spermatogenesis support (HMG), covering both male and female fertility biology from a single reproductive research buyer audience. Download the full catalog for all reproductive endocrinology category pricing.
Methodology & Data Sources
Methodology & Data Sources
Scientific literature: PubMed searched for “human chorionic gonadotropin,” “HCG LHCGR Leydig cell,” “HCG testosterone steroidogenesis,” and “HCG spermatogenesis fertility.” Search conducted through April 2026.
Key sources: Casarini et al. (2017) Reprod Biol Endocrinol (LH vs. HCG Leydig cell comparison; cAMP and testosterone equivalence); Riccetti et al. (2017, same group; LHCGR signaling); Esteves et al. (2025, 2026) Andrology (NOA HCG clinical review; Handelsman 2024 PK data); Balasch & Gratacos (ovulation induction systematic review); Wikipedia HCG article (structural context); Pierce & Parsons (1981) Annu Rev Biochem (glycoprotein hormone structural biology).
Limitations: Research-grade HCG is not equivalent to compound HCG (Pregnyl, Novarel, Ovidrel). IU potency of research-grade batches should be verified by bioassay; HPLC purity alone does not confirm biological activity for a glycoprotein hormone. HCG’s carbohydrate chains vary between preparations (urinary-derived vs. recombinant vs. research-grade) and may affect pharmacokinetic behavior. This article is for educational purposes only.
References
- Casarini, L., Lispi, M., Longobardi, S., et al. (2012). LH and hCG action on the same receptor results in quantitatively and qualitatively different intracellular signalling. PLoS One, 7(10), e46682. (LH vs. HCG signaling comparison.)
- Casarini, L., Crepieux, P. (2019). Molecular mechanisms of action of FSH. Front Endocrinol. (LHCGR/FSH receptor signaling context.)
- Simoni, M., & Casarini, L. (2014). Mechanisms in endocrinology: genetics of FSH action: a 2014-and-beyond view. Eur J Endocrinol, 170(3), R91–R107. (LH receptor/HCG binding context.)
- Riccetti, L., De Pascali, F., Gilioli, L., et al. (2017). Human LH and hCG stimulate differently the early signalling pathways but result in equal testosterone synthesis in mouse Leydig cells in vitro. Reprod Biol Endocrinol, 15(1), 2. (Spare receptor / cAMP equivalence data.)
- Esteves, S. C., et al. (2026). Human chorionic gonadotropin-based wellness supports for infertile men with non-obstructive azoospermia. Andrology. (Shiraishi NOA data; Handelsman 2024 PK equivalency.)
- Pierce, J. G., & Parsons, T. F. (1981). Glycoprotein hormones: structure and function. Annu Rev Biochem, 50, 465–495. (HCG structural biology foundational review.)
- Balasch, J., & Gratacos, E. (2012). Delayed childbearing: effects on fertility and the outcome of pregnancy. Curr Opin Obstet Gynecol. (IVF/ART HCG trigger context.)
- Stocco, D. M., & Clark, B. J. (1996). Regulation of the acute production of steroids in steroidogenic cells. Endocr Rev, 17(3), 221–244. (StAR protein steroidogenesis mechanism.)
- Rao, C. V. (2001). Multiple novel roles of luteinizing hormone. Fertil Steril, 76(6), 1097–1100. (Extragonadal LHCGR expression and function.)
Frequently Asked Questions
HCG (human chorionic gonadotropin; YPB.256; 5,000 IU configuration) is a glycoprotein hormone (α/β heterodimer; ~36,700 Da) that acts as a surrogate LH signal by binding the LHCGR (LH/chorionic gonadotropin receptor) on Leydig cells (testis) and luteal/granulosa cells (ovary). In research models, LHCGR activation by HCG drives: Gs → cAMP ↑ → PKA → StAR phosphorylation → cholesterol mitochondrial transport → CYP11A1 → pregnenolone → testosterone (males) or progesterone (corpus luteum, females). HCG is ~10-fold more potent than LH in cAMP recruitment in vitro due to extended sialic acid content; equivalent downstream testosterone synthesis. Half-life: ~24h (vs. ~20 min for LH); single injection provides sustained LHCGR stimulation. Research applications: Leydig cell steroidogenesis, male fertility (spermatogenesis induction when combined with FSH), ovulation trigger, corpus luteum biology, HPG axis pharmacology. WADA S2 Prohibited in males. Research-grade ≠ compound (Pregnyl, Novarel). Research Use Only (RUO). Updated April 2026.
LH and HCG bind the same LHCGR but differ critically in their β-subunit structure. The HCG β-subunit has an additional 24-amino acid C-terminal peptide (CTP) that is absent in LH β. This CTP carries O-linked oligosaccharide chains with extensive sialic acid residues. Sialic acid residues are negatively charged and slow renal clearance because the negatively charged kidney glomerular filtration barrier (also negatively charged) repels sialylated proteins, and because sialic acid prevents receptor-mediated uptake in the liver. The net result: HCG’s sialylated CTP dramatically extends plasma half-life to approximately 24 hours vs. approximately 20 minutes for pituitary LH, which lacks the sialylated CTP. This half-life difference is why a single HCG injection can reliably trigger ovulation at 36 hours post-injection (the timed ovulation protocol used in IVF), while pituitary LH pulse’s 20-minute half-life requires continuous endogenous pulsatile secretion to maintain gonadal stimulation. For research design: HCG provides sustained, time-controlled LHCGR stimulation; LH (when available) would provide more physiologically pulsatile stimulation. Most laboratory research uses HCG specifically because its pharmacokinetics are stable and controllable.
StAR (steroidogenic acute regulatory protein) is a 30-kDa mitochondrial protein that mediates the transport of cholesterol from the outer to the inner mitochondrial membrane — the rate-limiting, regulated step in steroidogenesis. The enzyme that converts cholesterol to pregnenolone (CYP11A1; P450scc; cholesterol side-chain cleavage enzyme) resides on the inner mitochondrial membrane. The outer mitochondrial membrane is impermeable to cholesterol; cholesterol must be physically transported across this barrier by StAR before steroidogenesis can proceed. StAR is regulated by HCG/LHCGR/cAMP/PKA: PKA phosphorylates StAR at Ser194, activating its cholesterol transport function and simultaneously inducing StAR gene transcription. Because StAR activity is the bottleneck between cholesterol availability and pregnenolone production, the rate of steroidogenesis in any given moment is determined by how much phospho-StAR is present and active. This is why HCG-stimulated testosterone synthesis can be acute: a single LHCGR activation event drives cAMP → PKA → StAR phosphorylation within minutes, rapidly increasing cholesterol transport rate and downstream testosterone output. StAR mutations (causing lipoid congenital adrenal hyperplasia) result in complete steroidogenesis failure, confirming its indispensable role.
HCG is prohibited in males (WADA S2 Prohibited List) because in men, HCG acts on Leydig cells to stimulate endogenous testosterone production. This creates a specific anti-doping problem: athletes wishing to elevate circulating testosterone for performance advantages could use HCG to stimulate their own Leydig cells to produce more testosterone. Because the testosterone produced is endogenous (synthesized by the athlete’s own Leydig cells), it does not show up in anti-doping tests as “exogenous testosterone” and does not trigger the testosterone carbon isotope ratio (IRMS/CIR) test that detects synthetic testosterone from compound sources. HCG therefore represents a masking strategy — producing elevated testosterone without the telltale exogenous androgen markers. HCG is not prohibited for female athletes because in females, HCG does not produce testosterone (its primary gonadal effect is ovarian progesterone production from corpus luteum cells), and because HCG has legitimate physiological roles in female biology (early pregnancy) that make blanket prohibition impractical and inequitable.
compound HCG products (Pregnyl, Novarel, Chorex = urinary-derived; Ovidrel/choriogonadotropin alfa = recombinant) are research-grade compound manufactured to compound GMP standards with extensive clinical safety and efficacy data, standardized potency, and sterility testing appropriate for clinical injection use. Research-grade HCG (YPB.256) is produced for laboratory research only and is not manufactured to compound GMP standards for human administration. Key distinctions: (1) Regulatory status: compound HCG is research-grade for specific indications; research-grade is Research Use Only and cannot be used for human administration; (2) Manufacturing standards: compound GMP vs. research-grade synthesis and QC; (3) Potency verification: compound products are potency-guaranteed to IU specifications against WHO reference preparations using validated in vivo bioassays; research-grade bioactivity confirmation uses in vitro assays (cAMP induction in LHCGR-expressing cells); (4) Sterilization and endotoxin: compound products are manufactured under aseptic conditions for injection; research-grade requires endotoxin testing (<1 EU/mg) for cell culture safety only. YPB research-grade HCG is appropriate for cell culture and in vitro research; it is not appropriate or legal for research use only.
Yes. YourPeptideBrand.com provides white-label dropship for HCG as YPB.256 (5,000 IU; Research Use Only). White-label storefronts include pre-built RUO-compliant product pages with LHCGR/cAMP/StAR mechanism descriptions, Leydig cell steroidogenesis research context, WADA S2 prohibited status clearly noted, and COA library links. Contact the YPB team for confirmed Premier and Core pricing, and use the profit calculator to model projected revenue.
Every HCG batch includes a lot-specific COA: HPLC purity, SDS-PAGE confirmation of α/β heterodimer (glycoprotein runs at characteristic MW under non-reducing/reducing conditions), bioactivity confirmation (cAMP induction in LHCGR-expressing cells or Leydig cell steroidogenesis assay at expected EC50), IU potency (standardized against WHO HCG reference preparation), endotoxin (<1 EU/mg), TAMC, and TYMC. The bioactivity assay and IU potency confirmation are the most critical quality parameters for HCG research because HPLC purity alone confirms chemical identity but not biological receptor activity. Glycosylation pattern varies between preparations and affects both receptor binding and pharmacokinetics. All lots are traceable through the batch-specific COA library.
HCG and HMG are the pharmacological pair for reproductive endocrinology: HCG provides the LH signal (Leydig cell testosterone; ovulation trigger); HMG provides the FSH + LH signal combination (Sertoli cell spermatogenesis support + folliculogenesis). Position them as “the gonadotropin research pair” rather than competing products. For male fertility research: HCG establishes the intratesticular testosterone environment; HMG adds the FSH-dependent Sertoli cell support required for complete spermatogenesis — mirroring the clinical protocol where combined HCG + HMG/FSH is the standard for inducing fertility in hypogonadotropic hypogonadism. For female fertility research: HCG is the ovulation trigger and corpus luteum maintainer; HMG supports folliculogenesis before the trigger. Any researcher studying fertility biology will need both tools, making them natural catalog companions with a single reproductive endocrinology buyer audience.
Key Takeaways
Research Takeaways
- Glycoprotein α/β heterodimer (~36,700 Da): Not a synthetic peptide; handle gently; no vortex; bacteriostatic water for reconstitution; glycosylation critical for receptor binding and half-life.
- LHCGR → Gs → cAMP → PKA → StAR → CYP11A1 → pregnenolone → testosterone: StAR phosphorylation is rate-limiting; spare receptor capacity means supraphysiological cAMP ≠ proportionally more testosterone.
- ~24h half-life vs. 20 min LH: Sialylated β-CTP (absent in LH) reduces renal clearance; sustained controllable LHCGR stimulation from single injection.
- ~10-fold more potent than LH in cAMP; equivalent testosterone: Spare receptor capacity in Leydig cell pathway; design research doses on linear dose-response range.
- HCG + FSH/HMG for spermatogenesis: HCG alone provides intratesticular testosterone but FSH required for Sertoli cells; combined protocol induces sperm production in 70–90% of hypogonadotropic models.
- WADA S2 Prohibited (males): Stimulates endogenous testosterone without exogenous androgen markers; potential masking compound.
- IU measurement (not mg): Activity-based; confirm IU potency and bioactivity in COA.
Business Takeaways
- 40,000+ PubMed publications — one of the most extensively researched hormones; broad established research audience across reproductive endocrinology, fertility, and andrology.
- Only LHCGR-selective gonadotropin in YPB catalog — unique HPG axis research tool for direct Leydig cell stimulation bypassing pituitary.
- HCG + HMG gonadotropin pair = complete LH/FSH/testosterone/sperm fertility research toolkit from a single reproductive biology buyer audience.
- Contact YPB for confirmed pricing on YPB.256 (5,000 IU).
Ready to add HCG to your research catalog? Book a consultation with the YPB team.
[ypb_studies peptide=”hcg”]