Gonadorelin
Synthetic gonadotropin-releasing hormone (GnRH) decapeptide, the hypothalamic trigger for LH and FSH secretion; used in diagnostics and research.
Overview
Gonadorelin is the synthetic form of gonadotropin-releasing hormone (GnRH), a hypothalamic decapeptide that controls the pituitary secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Synthetic gonadorelin has a long clinical history: it has been used to test pituitary gonadotroph function and, in pulsatile regimens, to treat hypogonadotropic hypogonadism by restoring the physiologic pulse pattern that drives reproductive function. The decapeptide sequence is highly conserved among mammals, reflecting its central role in reproduction. The distinction between pulsatile and continuous receptor exposure is the key determinant of whether the axis is stimulated or suppressed, a principle that also underlies GnRH agonist therapy. Because the native peptide is cleared within minutes, clinical protocols rely on pump-driven pulsatile delivery or on single diagnostic doses rather than conventional daily injections.
Mechanism
Gonadorelin binds GnRH receptors on pituitary gonadotroph cells. Delivered in pulses, it stimulates synthesis and release of LH and FSH, which in turn activate gonadal steroid production and gametogenesis. The route of administration determines the response: pulsatile exposure stimulates the axis, whereas continuous exposure desensitizes the receptor and suppresses gonadotropins.
Dosing
Approved uses include single-injection protocols for assessing pituitary function. Pulsatile therapy for hypogonadotropic hypogonadism is delivered by a programmable pump as low-microgram doses every 1-2 hours. Research dosing should follow the primary literature; the native peptide has a half-life of only minutes.
Expected Effects
- rapid, dose-dependent release of LH and FSH after administration
- restoration of gonadal steroid production and spermatogenesis or ovulation with pulsatile regimens in hypogonadotropic states
- diagnostic differentiation of hypothalamic versus pituitary causes of hypogonadism
Side Effects & Tolerability
Gonadorelin is generally well tolerated. Reported effects include transient flushing, headache, and injection-site reactions; serious hypersensitivity is rare. Continuous high-dose exposure would be expected to suppress rather than stimulate the axis.
Storage
Lyophilized gonadorelin should be stored frozen and desiccated, protected from light. Reconstituted solutions are short-lived and should be refrigerated at 2-8 deg C, with any remainder discarded per protocol.