Side-by-side · Research reference
GonadorelinvsPE 22-28
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AFDA-ApprovedHUMAN-REVIEWED7/61 cited
BAnimal-StrongHUMAN-REVIEWED16/47 cited
Gonadorelin
GnRH Analogue · Diagnostic & Therapeutic
IV / SQ · Pulsatile Pump (Therapeutic) · Single Bolus (Diagnostic)
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
01Mechanism of Action
Parameter
Gonadorelin
PE 22-28
Primary target
GnRH receptors on anterior pituitary gonadotropes
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
Pathway
GnRH → Pituitary gonadotrope → LH/FSH secretion → Gonadal steroidogenesisSharma 2026
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
Downstream effect
Pulsatile LH/FSH release stimulates testicular testosterone or ovarian estradiol/progesterone synthesis; initiates folliculogenesis and spermatogenesisRobin 2026Sharma 2026
Antidepressant-like activity in forced swim test and tail suspension test; reduced A1-like reactive astrocyte activation; neuroprotection via NF-κB pathway modulationDjillani 2017Cong 2023Wu 2021
Feedback intact?
Yes — pulsatile delivery preserves negative feedback loops; continuous exposure desensitizes receptors
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
Origin
Synthetic decapeptide (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) identical to native hypothalamic GnRH
Synthetic truncation of spadin (PE 12-28), itself derived from the sortilin propeptide C-terminus. Residues 22-28: Val-Val-Arg-Gly-Trp-Leu-Arg.Djillani 2017Mazella 2018
Antibody development
—
Not reported in animal studies
02Dosage Protocols
Parameter
Gonadorelin
PE 22-28
Diagnostic test (pituitary function)
100 mcg IV or SQ bolus
Measure baseline LH/FSH, then 30/60/90 min post-injection. Normal response: LH ≥2× baseline.
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Therapeutic (hypothalamic hypogonadism)
5–20 mcg IV bolus every 90–120 minutes
Requires portable pulsatile pump. Dose individualized to achieve normal gonadotropin pulsatility.Robin 2026
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Pulsatile interval
90 minutes (females) · 120 minutes (males)
Mimics physiological GnRH pulse frequency.
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Route
IV preferred (therapeutic) · SQ acceptable (diagnostic)
—
Duration
Continuous until pregnancy achieved or fertility goals met
3–6 month courses typical for ovulation induction.
—
Evidence basis
RCT / Expert consensus
Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017Qi 2018Wu 2021
Half-life
2–4 minutes (plasma)
Necessitates frequent pulsatile administration.
—
Alternative protocols
Exogenous gonadotropins (hCG/hMG) often preferred due to convenience vs pump requirement
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Animal dose (antidepressant)
—
0.3–3 µg/kg IP
Effective in forced swim test, tail suspension test, CUMS models.
Animal dose (neuroprotection)
—
0.03 µg/kg IPPietri 2019
Low-dose TREK-1 activation post-stroke for 7 days, then high-dose blockade.
Frequency
—
Once daily
Sustained antidepressant effect over 7+ days.
Onset (animal)
—
Within hours (acute); full effect 4–7 days
Comparison to fluoxetine
—
PE 22-28 outperforms fluoxetine in CUMS-sensitive rats by day 7
Chronic administration shows superior long-term efficacy.
Human equivalent (extrapolated)
—
Not established — no clinical trials
Allometric scaling from rodent data unavailable.
03Metabolic / Fat Loss Evidence
Parameter
Gonadorelin
PE 22-28
Fat loss mechanism
None — gonadorelin acts exclusively on reproductive axis
—
Indirect metabolic effects
Restoration of sex hormones may normalize body composition in hypogonadal states
Effect mediated by downstream testosterone/estradiol, not GnRH itself.
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04Side Effects & Safety
Parameter
Gonadorelin
PE 22-28
Injection site reaction
Erythema, irritation (pulsatile pump catheter site)
—
Headache
Common with bolus administration
—
Nausea / abdominal discomfort
Transient, dose-related
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Ovarian hyperstimulation syndrome (OHSS)
Risk with ovulation induction protocols; monitor follicular development via ultrasound
—
Multiple gestation
Increased risk with fertility protocols (twins ~10–15%)
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Anaphylaxis
Rare hypersensitivity reaction
—
Pump malfunction / infection
Mechanical failure or catheter-site infection with long-term IV pump use
—
Receptor desensitization
Continuous (non-pulsatile) exposure paradoxically suppresses gonadotropinsRobin 2026
—
Toxicity (animal)
—
No adverse effects reported at therapeutic doses
Cardiovascular (theoretical)
—
TREK-1 expressed in cardiac tissue; arrhythmia risk unclear
Weight change
—
Not reported in animal studies
Neurological
—
No seizures or behavioral abnormalities noted
Long-term safety
—
Unknown — longest animal study 28 days
Absolute Contraindications
Gonadorelin
- ·Pregnancy (except therapeutic infertility protocols)
- ·Hypersensitivity to gonadorelin or excipients
- ·Hormone-dependent tumors (prostate, breast) — risk of tumor stimulation via sex hormone elevation
PE 22-28
- ·Human use — no clinical safety data available
Relative Contraindications
Gonadorelin
- ·Ovarian cysts or PCOS (monitor for OHSS)
- ·Pituitary adenoma or other sellar mass (may worsen with gonadotropin surge)
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
05Administration Protocol
Parameter
Gonadorelin
PE 22-28
1. Diagnostic protocol
Administer 100 mcg IV or SQ bolus. Draw baseline LH/FSH, then at 30, 60, 90 minutes. Normal response: LH ≥2× baseline, FSH modest rise. Blunted response suggests pituitary pathology; exaggerated response may indicate primary hypogonadism.
Dissolved in sterile saline or vehicle. Intraperitoneal injection, 0.3–3 µg/kg body weight. Once daily administration in rodent behavioral studies.
2. Therapeutic pump setup (pulsatile)
Requires programmable infusion pump with IV catheter. Set pulse interval to 90 min (females) or 120 min (males). Bolus dose 5–20 mcg per pulse. Pump worn continuously; catheter site rotated every 48–72 hrs to prevent infection.
Shorter peptide length (7 AA) confers improved plasma stability vs 17-AA spadin. Exact storage conditions not detailed in published protocols.Djillani 2017
3. Reconstitution
Lyophilised gonadorelin reconstituted with sterile saline or provided diluent. Typically 0.8–3.2 mg dissolved in 8 mL for pump reservoir. Solution stable 7–14 days refrigerated.
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
4. Monitoring
For fertility protocols: ultrasound follicular tracking + serial estradiol/LH measurements. Adjust pulse dose to achieve mid-follicular LH 5–10 IU/L. Ovulation confirmed by progesterone rise or ultrasound.
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.
5. Timing
Pulsatile therapy initiated at any point in cycle. Diagnostic test performed in morning (higher baseline LH). For ovulation induction, treatment begins early follicular phase.
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06Stack Synergy
Gonadorelin
+ hCG (Human Chorionic Gonadotropin)
Multi-pathwayIn hypogonadotropic hypogonadism protocols, gonadorelin restores pituitary LH/FSH pulsatility, while exogenous hCG directly stimulates Leydig cells (acting as LH mimetic) to maintain testosterone production. This dual approach ensures both central axis restoration and immediate gonadal steroidogenesis, preventing testicular atrophy during fertility treatment. hCG's longer half-life (24–36 hrs) complements gonadorelin's pulsatile short-acting profile.
- Gonadorelin
- 5–10 mcg IV every 120 min (pulsatile pump)
- hCG
- 1500–2000 IU SQ · 2–3× per week
- Duration
- 12–24 weeks for spermatogenesis induction
- Primary benefit
- Fertility restoration in hypothalamic hypogonadism with maintained testicular function
PE 22-28
— no documented stacks