Description
Summary Abstract
Human menopausal gonadotropin (HMG) is a purified urinary gonadotropin preparation derived from the urine of postmenopausal women, containing a combined mixture of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activity in approximately equal ratio (typically 75 IU FSH : 75 IU LH per ampoule in standard preparations). Both FSH and LH are heterodimeric glycoprotein hormones sharing the same 92-amino-acid α-subunit while differing in their β-subunits, which confer receptor specificity. FSH binds the FSH receptor (FSHR) on granulosa and Sertoli cells; LH binds the LH/chorionic gonadotropin receptor (LHCGR) on theca and Leydig cells. The coordinated FSH/LH activity of HMG recapitulates the physiological two-cell model of ovarian steroidogenesis, making it an essential research and clinical tool for follicular stimulation protocols, assessment of gonadotropin responsiveness, and reproductive endocrinology investigations.
Clinical Indications
HMG is used in controlled ovarian stimulation and gonadotropin biology research:
- Follicular development and ovulation induction: HMG provides the coordinated FSH signal for granulosa cell proliferation and estradiol production and the LH signal for theca cell androstenedione synthesis — the two-cell model — enabling physiologically complete follicular maturation in research and clinical protocols.
- Male hypogonadotropic hypogonadism research: Combined FSH/LH replacement via HMG restores both spermatogenesis (FSH-dependent) and testosterone production (LH-dependent) in gonadotropin-deficient models, making it a comprehensive tool for male reproductive axis investigation.
- Gonadotropin receptor biology: HMG serves as a pharmacological reference preparation for FSHR and LHCGR signaling studies, comparative potency assessments, and investigation of gonadal responsiveness across species.
Contraindications
- Ovarian hyperstimulation syndrome (OHSS): The LH component of HMG, combined with FSH-driven multiple follicular development, carries significant OHSS risk in high-stimulation protocols; dose titration and estradiol monitoring are essential in any high-stimulation ovarian model.
- Gonadotropin-responsive tumor models: Both FSHR and LHCGR are expressed on some gonadal tumor cell lines; HMG should not be used in models where gonadotropin-driven cell proliferation would confound outcomes.
- Anti-doping status: Both FSH and LH components fall under WADA S2 (Peptide Hormones, Growth Factors); relevant institutional governance and disclosure are required for sport-adjacent research applications.
Mechanism of Action (MOA)
HMG exerts its gonadotropic effects through the combined and synergistic actions of its FSH and LH components on gonads:
FSH Component — Granulosa and Sertoli Cell Signaling
The FSH component of HMG binds the FSH receptor (FSHR), a Gsα-coupled GPCR on ovarian granulosa cells and testicular Sertoli cells. In the ovary, FSH-cAMP signaling stimulates granulosa cell proliferation, CYP19A1 (aromatase) expression for estradiol synthesis, inhibin B production, and LH receptor upregulation preparing cells for the ovulatory trigger. In the testis, FSH drives Sertoli cell support of spermatogenesis.
LH Component — Theca Cell and Leydig Cell Steroidogenesis
The LH component binds LHCGR on ovarian theca cells and testicular Leydig cells via the same Gsα-cAMP-PKA-StAR cascade described for HCG. In the ovary, theca cells produce androstenedione via CYP17A1, which granulosa cells aromatize to estradiol — the two-cell, two-gonadotropin model. In the testis, LH sustains testosterone biosynthesis.
Two-Cell Ovarian Steroidogenesis Model
The physiological elegance of the two-cell model requires both LH and FSH activity simultaneously: LH stimulates theca cells to produce androgen precursors; FSH simultaneously drives granulosa cells to express CYP19A1 aromatase, converting theca-derived androgens to estradiol. HMG uniquely provides both signals in a single preparation, closely recapitulating the physiological endocrine milieu.
Multiple Follicular Development
By elevating supraphysiological FSH concentrations while providing LH support, HMG bypasses the endogenous hypothalamic-pituitary feedback axis (which normally limits FSH to a level that allows only one dominant follicle per cycle). This enables controlled multiple follicular development (COH) — the basis of assisted reproduction protocols and a research model for examining FSH dose-response and follicular recruitment thresholds.
Key Features & Specifications
HMG uniquely delivers the dual FSH/LH signal required for the complete physiological two-cell steroidogenesis model:
Chemical Analysis
| Property | Specification Reference Data |
|---|---|
| Class | Purified urinary gonadotropin preparation; FSH + LH mixture |
| FSH Component | Heterodimeric glycoprotein; α-subunit (92 aa, shared) + FSH-specific β-subunit (111 aa); MW ~34 kDa |
| LH Component | Heterodimeric glycoprotein; α-subunit (92 aa, shared) + LH-specific β-subunit (121 aa); MW ~28 kDa; t½ ~60 min |
| Standard Activity Ratio | 75 IU FSH : 75 IU LH per ampoule (may vary by preparation) |
| Receptor Targets | FSH receptor (FSHR, Gsα GPCR) + LH/CG receptor (LHCGR, Gsα GPCR) |
| Route | Intramuscular or subcutaneous injection (lyophilized) |
| Form / Variation | Standard lyophilized — P-0799796960076880 ($42.00) |
Storage, Safety, and Handling
Storage Protocol
Store lyophilized HMG at 2–8 °C (refrigerator), protected from light and moisture. Reconstitute with sterile saline or bacteriostatic water immediately before use; reconstituted solution is stable at 2–8 °C for up to 28 days. Do not freeze reconstituted glycoprotein preparations — freezing denatures the protein and compromises biological activity.
Handling & Compliance
Use aseptic technique and standard PPE for reconstitution and preparation of injectable solutions. HMG falls under regulatory frameworks governing urinary-derived protein pharmaceuticals; institutional ethics approval (IACUC for animal studies; IRB for human protocols) is required. Both FSH and LH are WADA S2 prohibited substances.