Gonadorelin Peptide: Structure, Research & Science Guide

By The Peptides Codex Editorial TeamReviewed September 8, 2026

Page data last changed: 2026-10-05. Registry refreshes and identity assessments are separate from scientific content review.

Reference backbone length

10 positions

Class

Hypothalamic decapeptide hormone (GnRH), synthetic

Function

Stimulates pulsatile release of LH and FSH from the anterior pituitary via the GnRH receptor

Context

Approved in various markets as a diagnostic agent for pituitary function and, by pulsatile pump, for fertility; widely approved in veterinary medicine; not a research-only compound

The reproductive axis's master switch, ten residues long: pulsed, it turns the gonads on; given continuously, its analogues turn them off.

Also known as: GnRH · GnRH-I · LHRH · gonadorelin acetate · gonadorelin hydrochloride · Fertagyl (veterinary)

Part of the Foundational & therapeutic peptides cluster

Overview

Gonadorelin is the synthetic form of gonadotropin-releasing hormone (GnRH, also LHRH), the hypothalamic decapeptide pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 that drives pituitary release of luteinising and follicle-stimulating hormone. It is chemically identical to the human hormone, has a half-life of minutes, and is used as a diagnostic stimulation test, in pulsatile-pump fertility treatment, and extensively in veterinary reproduction. Its long-acting agonist and antagonist analogues — leuprolide, triptorelin, ganirelix and others — are separate profiles.

Source & context

Biological / chemical source: Synthetic form identical to endogenous gonadotropin-releasing hormone

Primary research or clinical context: Approved in various markets as a diagnostic agent for pituitary function and, by pulsatile pump, for fertility; widely approved in veterinary medicine; not a research-only compound

What gonadorelin is

Gonadorelin is the synthetic, chemically identical form of gonadotropin-releasing hormone (GnRH), the ten-residue peptide that hypothalamic neurons release in pulses to tell the pituitary to secrete luteinising hormone (LH) and follicle-stimulating hormone (FSH). Historically it was called luteinising-hormone-releasing hormone (LHRH), and PubChem lists it under both names and under the veterinary brand Fertagyl. Formula C55H75N17O13, average mass about 1,182 Da, CAS 33515-09-2. Because it is the native hormone rather than an analogue, everything about its behaviour — a half-life of minutes, and opposite effects depending on whether it is pulsed or sustained — is the physiology of the reproductive axis itself.

Sequence and chemistry

The sequence is pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2. The N-terminal pyroglutamate (a cyclised glutamine) and the C-terminal glycinamide are native features that already protect the ends from exopeptidases; what limits the hormone's life is endopeptidase cleavage at the Gly6–Leu7 and Pro9–Gly10 bonds. Every long-acting agonist analogue — leuprolide, triptorelin, buserelin, nafarelin — substitutes a D-amino acid at position 6 and modifies or replaces glycine 10 for exactly that reason, while antagonists such as ganirelix rebuild the N-terminus as well. Gonadorelin is the reference point those profiles are measured against.

Mechanism: pulse frequency is the message

GnRH acts on a single receptor on pituitary gonadotrophs, but the outcome depends on timing. The hypothalamus releases it roughly hourly; each pulse triggers LH and FSH release, and the pulse frequency encodes which gonadotropin dominates. Continuous exposure does the opposite: the receptor is internalised and desensitised within days and gonadotropin output collapses. That single fact explains the whole drug family. Gonadorelin, with its minutes-long half-life, is used when a physiological pulse is wanted; agonist analogues with hours-long half-lives are used precisely because their sustained signal shuts the axis down, which is how they treat prostate cancer, endometriosis and precocious puberty.

One receptor, two outcomes
Signal	Receptor response	Effect on LH / FSH	Used for
Pulsatile (gonadorelin by pump)	Normal activation	Physiological release	Hypothalamic amenorrhoea, ovulation induction
Single bolus (gonadorelin)	Acute activation	LH surge measured	Pituitary stimulation test
Continuous (agonist analogues)	Desensitisation	Suppressed after initial flare	Prostate cancer, endometriosis, puberty suppression
Blockade (antagonists)	Competitive inhibition	Suppressed immediately	IVF, prostate cancer

Human uses

Gonadorelin's human uses follow from its short action. As a diagnostic, a single dose provokes a measurable LH and FSH response that tests pituitary gonadotroph function. In fertility medicine it can be delivered by a portable pump that mimics the natural pulse to induce ovulation in women whose own hypothalamic signal is absent. Availability differs by country and formulation, and the human products have been discontinued or replaced in some markets, so approval status should be checked locally. The literature returned for the name is dominated by reviews of GnRH-analogue therapy in endometriosis, heavy menstrual bleeding and breast disease, which concern the long-acting analogues rather than gonadorelin itself.

Veterinary use

Gonadorelin is far more widely used in animals than in people. Products such as Fertagyl are approved for cattle to treat cystic ovaries and to synchronise ovulation in timed-insemination programmes, and it is used in other livestock and companion-animal reproduction. That veterinary market is one reason the peptide is inexpensive and widely available, and one reason it appears in grey-market listings alongside human research peptides.

The grey-market context

Gonadorelin is sold online to men using exogenous testosterone in the belief that it will maintain testicular function, on the model of human chorionic gonadotropin. The physiology above explains the difficulty: a peptide with a half-life of minutes produces a brief pulse, and the effect of intermittent self-injection on LH output has not been studied in controlled trials. The registered-trial count on ClinicalTrials.gov for the term “gonadorelin” — over a thousand — reflects analogue trials that match the name, not studies of this use. This profile is educational and does not offer guidance on any regimen.

Status

Gonadorelin is an approved active substance in human diagnostic and fertility products in various jurisdictions and in veterinary products in most, with the specific human products varying by country. It is not a controlled substance. Material sold as a research chemical for human self-administration is outside any approval and of unverified content. This page is not medical advice.

Sequence of the selected reference form

Sequence backbone for the reference form: Gonadorelin parent GnRH-I amide. Termini, stereochemistry and modifications are described below.

XHWSYGLRPG

X1 is L-pyroglutamate; Gly10 is amidated.. X marks a noncanonical residue; see the expanded sequence and reference chemistry below.

Analyze sequences in the playground →

Structure & chemistry

Molecular identity & reference confidence

Source-supported reference

The selected mammalian GnRH-I parent has pyroglutamate1 and Gly10 amidation. Official labels distinguish this parent from acetate/HCl salts. The old linked CID returns a different molecular formula, not the selected gonadorelin formula.

Molecular form: Gonadorelin parent GnRH-I amide
Species: Mammalian GnRH-I sequence; bovine endogenous identity is explicitly documented in the veterinary label
Termini (N / C): L-pyroglutamyl lactam / Glycinamide (Gly10-NH2)

Average reference mass · Molecular identity assessment: 2026-10-05

Reference policy updated: 2026-10-05

PubChem PUG REST selected parent properties · 2026-10-05
PubChem selected-parent biologic notation · 2026-10-05
PubChem selected-parent identifiers with depositor attribution · 2026-10-05
NIH GSRS independently selected parent record · 2026-10-05
Official product label chemical description, selected parent distinguished from formulation · 2026-10-05

Full sequence with modifications

H-Pyr-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2

Molecular formula: C55H75N17O13
Average reference mass: ≈ 1,182.3
Plasma half-life: Minutes — rapidly cleaved by peptidases at Gly6-Leu7 and Pro9-Gly10; the reason its analogues substitute those positions
Receptors: GnRH receptor (GnRHR), a Gq-coupled receptor on pituitary gonadotrophs; pulsatile activation releases LH and FSH, continuous activation desensitises the receptor
Backbone: Gonadorelin parent GnRH-I amide
C-terminus: Glycinamide (Gly10-NH2)
Status: Approved: diagnostic and pulsatile-fertility use in various human markets; veterinary products (e.g. Fertagyl) widely approved

Identifiers

PubChem CID: 638793
CAS RN: 33515-09-2
UNII: 9O7312W37G

Chemistry values: curated profile, PubChem.

Clinical development snapshot

ClinicalTrials.gov lists 1,162 registered studies with “Gonadorelin” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.

Registered studies

1,162

Highest phase reached

Phase 4

Active in latest 100

Most recent update

2026-10-01

Most recently updated studies
NCT	Title	Phase	Status	Updated
NCT07460752	Evaluation of Alternative Site Goserelin Acetate Injection for Ovarian Function Suppression (OFS) in Local and	Phase 2	recruiting	2026-10-01
NCT02115282	Exemestane With or Without Entinostat in Treating Patients With Recurrent Hormone Receptor-Positive Breast Can	Phase 3	active not recruiting	2026-10-01
NCT07235917	A Study to Investigate Mibavademab in Adult Women With Functional Hypothalamic Amenorrhea	Phase 2	recruiting	2026-10-01
NCT05161195	Roll-over Study to Allow Continued Access to Ribociclib	Phase 4	active not recruiting	2026-10-01
NCT05827081	Phase IIIb Study of Ribociclib + ET in Early Breast Cancer	Phase 3	recruiting	2026-10-01
NCT01630967	Efficacy Study of Switching to a Lutenizing Hormone-releasing Hormone (LHRH) Antagonist From a LHRH Agonist to	Phase 2	withdrawn	2026-10-01

See all on ClinicalTrials.gov →

Concentration math

Gonadorelin — reconstitution calculator

Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.

Reference form: Gonadorelin parent GnRH-I amideAverage reference mass: 1,182.32 Da

Peptide in vial (mg)

Diluent added (mL)

Syringe graduation

Solution concentration

5 mg/mL5,000 mcg/mL

Amount to measure (optional)

mcg

Enter an amount to see the volume it corresponds to.

Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.

Open the Gonadorelin calculator on its own page →

Change log

Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.

2026-10-01ChemistryPubChem formula updated to C55H75N17O13.
2026-10-01Trials6 registered studies added on ClinicalTrials.gov (now 1162).
2026-09-08EditorialProfile content reviewed and updated by the editorial team.

FAQ about Gonadorelin

What is Gonadorelin?+

What Canadian product status is recorded for Gonadorelin?+

Canadian product status for Gonadorelin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.

What is the length of the selected reference form for Gonadorelin?+

The selected reference form (Gonadorelin parent GnRH-I amide) has 10 residues or residue-derived units in its backbone. Other forms in this family may have a different length.

What is gonadorelin?+

The synthetic form of gonadotropin-releasing hormone (GnRH/LHRH), the ten-residue hypothalamic peptide that triggers pituitary release of LH and FSH. It is identical to the human hormone.

How does gonadorelin work?+

It activates the pituitary GnRH receptor. Given in pulses it releases LH and FSH; given continuously, GnRH signalling desensitises the receptor and suppresses them — which is how its long-acting analogues work.

What is gonadorelin used for?+

Pituitary stimulation testing, pulsatile-pump ovulation induction, and, widely, veterinary reproduction (cattle ovulation synchronisation).

What is the sequence of gonadorelin?+

pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2; formula C55H75N17O13, mass about 1,182 Da.

Gonadorelin vs HCG — are they the same?+

No. HCG is a large glycoprotein that acts directly on the gonads like LH; gonadorelin is a decapeptide that acts on the pituitary to release LH and FSH, and only for minutes per dose.

Is gonadorelin approved?+

Yes, as a diagnostic and pulsatile-fertility agent in various human markets and in veterinary products; specific human products vary by country.

Related peptides

BPC-157

Research pentadecapeptide (gastric-juice-derived sequence)

BPC-157 (Body Protection Compound-157) is a synthetic 15-residue peptide, GEPPPGKPADDAGLV, derived from a sequence found in human gastric juice. Hundreds of rodent studies, most from a single Zagreb group, report accelerated healing of tendon, muscle, ligament, gut and skin injuries via VEGFR2, nitric-oxide and ERK1/2 pathways. Human evidence is limited to a small safety study and a retrospective chart review; the first phase 2 efficacy trial began recruiting in 2026. It is not approved anywhere and the FDA barred it from compounding in 2023.

TB-500

Synthetic thymosin β4 fragment (research peptide)

TB-500 is the synthetic, N-acetylated heptapeptide Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ), corresponding to residues 17–23 of thymosin β4, the protein's actin-binding motif. It first appeared as a veterinary preparation and is sold as a research chemical; its metabolism has been characterised in rats. A 2026 rat tendon study reported benefits with vendor-labelled TB-500 whose sequence was not characterized, so it does not establish efficacy of Ac-LKKTETQ. The fragment has no published human efficacy data. No product-specific authorization record has been verified in this profile; human trial registration does not establish approval. Its first registered human trial began recruiting in 2026.

Tirzepatide

Incretin dual agonist

Tirzepatide is a 39-amino-acid synthetic peptide (C225H348N48O68, ≈4,814 Da) that activates both the GIP and GLP-1 receptors. Its backbone is derived from GIP, with an exendin-4-like C-terminal tail, Aib residues at positions 2 and 13, and a C20 fatty diacid on Lys20 that binds albumin for a half-life of about 5 days. Approved as Mounjaro (type 2 diabetes, 2022) and Zepbound (weight management, 2023; obstructive sleep apnoea, 2024).

Retatrutide

Incretin triple agonist

Retatrutide (LY3437943) is an investigational 39-amino-acid peptide (C221H342N46O68, ≈4,731 Da) that activates three receptors — GIP, GLP-1 and glucagon. It shares its GIP-based scaffold and exendin-4 tail with tirzepatide, adds α-methyl-leucine and a second Aib, and carries a C20 fatty diacid on Lys17 for a half-life of about 6 days. In phase 2 it produced a mean weight change of −24.2% at 48 weeks; phase 3 trials are ongoing and it is not yet approved.

References & further reading

Disclaimer: Educational content only. Not medical advice. Not instructions for human use. Research peptides and unapproved products may be restricted or illegal to market for human consumption in your jurisdiction. Consult qualified professionals and applicable law.

You might also like: All peptides · Atlas · Research · Tools

Cite this: Peptides Codex — Gonadorelin educational profile.

Tip: Use browser print (Ctrl/Cmd + P) for a clean PDF of this page.