Reproductive
Reproductive3 peptides in this category
Gonadorelin is the synthetic form of gonadotropin-releasing hormone (GnRH), a naturally occurring decapeptide secreted in pulses by hypothalamic neurons to regulate the hypothalamic-pituitary-gonadal (HPG) axis. It is FDA-approved as Factrel for GnRH stimulation testing and as Lutrepulse for pulsatile delivery in female infertility due to hypogonadotropic hypogonadism. Gonadorelin is the identical sequence to native human GnRH: pyroglutamyl-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2. The N-terminal pyroglutamate (pGlu) and C-terminal amide protect against degradation. Its very short half-life (~2–4 minutes in plasma) is biologically intentional — it necessitates pulsatile delivery for therapeutic HPG stimulation, since continuous exposure leads to receptor downregulation and paradoxical gonadotropin suppression.
Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by syncytiotrophoblast cells of the placenta during pregnancy. It is an FDA-approved pharmaceutical available as Pregnyl and Novarel (powder for reconstitution, IM/SC injection) and as Ovidrel (subcutaneous injection of recombinant choriogonadotropin alfa). It is approved for treatment of hypogonadotropic hypogonadism in males, cryptorchidism in prepubertal males, and ovulation induction in females. hCG is technically not a peptide — it is a glycoprotein heterodimer with a molecular weight of approximately 36,700 Da (protein backbone; full glycosylated form is ~37,000–38,000 Da). It is conventionally categorized with peptide research compounds by vendors because its pharmacological target and clinical use (HPG axis modulation) overlap substantially with peptide therapeutics like gonadorelin and kisspeptin.
Kisspeptin is a neuropeptide produced by KNDy neurons (kisspeptin/neurokinin B/dynorphin neurons) in the arcuate nucleus of the hypothalamus. It is encoded by the KISS1 gene and acts on KISS1R (GPR54) receptors on hypothalamic GnRH neurons, making it the master upstream regulator of the hypothalamic-pituitary-gonadal axis. Kisspeptin is investigational for reproductive disorders including hypothalamic amenorrhea, IVF oocyte triggering, and idiopathic hypogonadotropic hypogonadism; no therapeutic form has received regulatory approval. The most studied forms are kisspeptin-10 (KP-10, 10 amino acids, C-terminal fragment) and kisspeptin-54 (KP-54, 54 amino acids, full-length). Both bind KISS1R with equivalent receptor-level potency; KP-54 has longer plasma half-life. The sequence listed above is KP-10 (the research-grade vendor form typically sold as lyophilized powder).