LIVE
GnRH receptor agonists (Gonadorelin), kisspeptin, oxytocin, and PTH fragments (Teriparatide) — peptides that act directly on endocrine-axis receptors.
This category covers peptides that act as direct agonists on classical endocrine-axis receptors, independent of the GH axis (which has its own category).
Gonadorelin is synthetic GnRH — the decapeptide released by the hypothalamus that triggers LH and FSH secretion from the anterior pituitary. Research uses include HPG-axis restoration protocols and induction of ovulation. It was FDA-approved in the past under the brand Factrel (discontinued) and is now available in the US only through compounding pharmacies. Kisspeptin-10 is a C-terminal decapeptide fragment of the KISS1 gene product; it acts upstream of GnRH on hypothalamic KISS1R receptors and is studied for reproductive and metabolic endocrinology.
Oxytocin is a nine-amino-acid posterior-pituitary peptide best known for its role in parturition and lactation; it is FDA-approved as an injectable obstetric agent under the brand Pitocin. Research interest spans social-bonding circuits and hypothalamic pharmacology. Teriparatide is a recombinant fragment of parathyroid hormone (PTH 1-34), FDA-approved as Forteo for osteoporosis; it stimulates bone formation via PTH1R agonism in a pulsatile-dosing regime that contrasts with continuous PTH's resorptive effect.
Of the four, teriparatide and oxytocin hold current active FDA approvals for their respective clinical indications. Research vendors typically sell all four as lyophilized powders for in-vitro and animal work.