Gonadorelin vs IGF-1 LR3
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Gonadorelin
Synthetic form of endogenous gonadotropin-releasing hormone (GnRH) that stimulates LH and FSH release from the anterior pituitary. Used in TRT protocols to maintain testicular function and prevent atrophy during exogenous testosterone administration. Preserves spermatogenesis and endogenous testosterone production capacity.
Full profileIGF-1 LR3
IGF-1 LR3 (Long Arg3 IGF-1) is a synthetic analogue of Insulin-like Growth Factor 1 with an amino acid substitution at position 3 and a 13-amino acid N-terminal extension. These modifications prevent binding to IGF-binding proteins (IGFBPs), dramatically extending its half-life from ~12 minutes (native IGF-1) to approximately 20–30 hours. IGF-1 LR3 is widely used in research for its ability to promote cellular growth, protein synthesis, hyperplasia, and nutrient uptake into muscle tissue.
Full profile| Gonadorelin | IGF-1 LR3 | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | GnRH, gonadotropin-releasing hormone, Factrel, Lutrepulse | Insulin-like Growth Factor-1 Long R3, Long R3 IGF-1, Increlex (human equivalent) |
| Evidence | Research-stage | Research-stage |
| Dosing range | 50mcg–200mcg mcg, 2–3x per week subcutaneous | 20mcg–100mcg mcg, Once daily post-workout, on training days only (common protocol) |
| Administration | Subcutaneous injection, Intranasal (pulsatile delivery) | Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols) |
| Key side effects | Injection site reactions, Headache, Nausea, Flushing | Hypoglycemia (clinically significant — monitor blood sugar carefully), Jaw and organ growth with chronic high-dose use (theoretical at research doses), Fatigue and headaches, Joint pain |
| Cited sources | 2 references | 3 references |
Key differences
- Administration: Gonadorelin — Subcutaneous injection, Intranasal (pulsatile delivery); IGF-1 LR3 — Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols).
- Frequency: Gonadorelin is typically 2–3x per week subcutaneous; IGF-1 LR3 is Once daily post-workout, on training days only (common protocol).
- Research depth: this profile cites 2 sources for Gonadorelin vs 3 for IGF-1 LR3.
How each works
Gonadorelin
Gonadorelin directly binds GnRH receptors in the anterior pituitary to trigger LH and FSH secretion, which in turn stimulates Leydig cells for testosterone production and maintains spermatogenesis. Used as a TRT adjunct, pulsatile gonadorelin administration mimics natural hypothalamic GnRH to prevent testicular suppression associated with exogenous androgen use.
IGF-1 LR3
In vitro and animal research establishes IGF-1 LR3 as a potent anabolic and growth-promoting agent. It activates the IGF-1 receptor (IGF-1R) and downstream PI3K/Akt and MAPK/Erk pathways, promoting skeletal muscle hypertrophy and satellite cell activation. Its extended half-life makes it far more active systemically than native IGF-1. Research also documents its role in connective tissue repair, nerve regeneration, and fat oxidation. Human research is limited — most data comes from cancer cell biology and athletic performance settings.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.