HMG (Menotropin): Scientific Profile

Publicado el 12 de julio de 2026

HMG (Menotropin), CAS 61489-71-2, is a preparation of human menopausal gonadotropin purified from the urine of postmenopausal women, with combined FSH and LH activity. For use in endocrinological and reproductive research. Its mechanism is based on the stimulation of the gonadotropic receptors that regulate folliculogenesis and steroidogenesis.

HMG (Menotropin), also known as human menopausal gonadotropin (Human Menopausal Gonadotropin), is a classic biological preparation within the class of gonadotropic hormones. It is identified by CAS number 61489-71-2 and is obtained by extraction and purification from the urine of postmenopausal women, a source rich in gonadotropins owing to the absence of ovarian negative feedback that characterizes this physiological stage. Unlike a single-sequence synthetic peptide, menotropin is a mixture of glycoproteins and therefore has no single, well-defined molecular formula or molecular weight; it is characterized instead by its standardized biological activity, historically expressed in international units (IU) of FSH and LH.

In terms of its composition, HMG provides mainly follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activity, traditionally in a ratio close to 1:1 depending on the preparation. Both are heterodimeric glycoproteins composed of a common alpha subunit, also shared with TSH and hCG, and a specific beta subunit that confers biological specificity. Menotropin preparations extracted from urine may also contain some human chorionic gonadotropin (hCG) activity, which contributes to the LH-type component. Highly purified variants (HMG-HP) reduce the content of accompanying urinary proteins, improving the batch-to-batch consistency used in research models.

The mechanism of action of HMG is based on the activation of G protein-coupled gonadotropin receptors. The FSH component binds to its receptor on ovarian granulosa cells and testicular Sertoli cells, promoting cell proliferation, follicular maturation (folliculogenesis), and expression of the enzyme aromatase, which converts androgens into estrogens. The LH component acts on theca cells and on Leydig cells, stimulating steroidogenesis and the production of androgenic precursors. Signaling of both receptors typically converges on the adenylate cyclase/cAMP/PKA pathway, which regulates the transcription of steroidogenic genes. Taken together, this combination approximately reproduces the physiological signal that the anterior pituitary sends to the gonads, which has made menotropin a reference tool for the study of the hypothalamic-pituitary-gonadal axis.

Regarding the documented research applications, menotropin belongs to a pharmacological class with a long trajectory and its gonadotropic activity has been extensively characterized in experimental models of reproduction and endocrinology. In laboratory contexts it has been used as a reference agent to study folliculogenesis, the ovarian response to gonadotropic stimulation, the dynamics of steroidogenesis, and the mechanisms of follicular recruitment and selection. In animal models, menopausal-origin gonadotropins have been used to induce controlled follicular responses and to investigate the signaling of FSH and LH receptors. It has also served as a comparator in studies that evaluate recombinant gonadotropins versus urine-derived preparations, providing information about the relative contribution of LH/hCG activity to the outcomes of follicular maturation. These lines of work allow researchers to dissect the biology of the reproductive axis and to calibrate experimental systems of cell culture and hormonal response.

The level of evidence supporting the biological activity of the menotropin class is solid and clinical in nature, in the sense that human menopausal gonadotropins constitute one of the best-characterized categories of gonadotropic hormones and one with the longest history of study within reproductive endocrinology. Their pharmacology, their receptor profile, and their effects on steroidogenesis and folliculogenesis are well established in the physiological literature. Nonetheless, this preparation—as a research material—must be handled strictly within the framework of controlled experimental work. All the information presented here is offered for purposes of scientific characterization and support for the design of studies in laboratory research models.

It is important to emphasize the nature of HMG as a derived and heterogeneous biological product. As a mixture obtained by extraction, its purity, its FSH:LH ratio, and the presence of accompanying proteins can vary according to the purification process, which is why standardization by biological activity (IU) is more informative than any mass measurement. Researchers working with menotropin must take batch-to-batch variability into account, verify the corresponding certificate of analysis, and carefully control the reconstitution and storage conditions, since it is a sensitive glycoprotein material that can lose activity when exposed to heat, excessive mechanical agitation, or improper storage after reconstitution.

In summary, HMG (Menotropin) is a human menopausal gonadotropin with combined FSH and LH activity, a well-established reference tool for the investigation of the reproductive axis and of gonadotropic signaling. Its experimental value lies in its ability to closely reproduce the physiological gonadotropic signal, which makes it useful in studies of folliculogenesis, steroidogenesis, and hormone receptor biology within rigorously controlled laboratory settings.