Growth Hormone Peptides: HGH, Ipamorelin, CJC-1295, Sermorelin & More | PeptidesDirect
Complete guide to hormonal peptides: HGH, Ipamorelin, CJC-1295, Sermorelin, Tesamorelin, HCG, IGF-LR3 & Melanotan 2. Compare mechanisms and research applications.
Growth Hormone and Hormonal Peptides for Research
Hormonal peptides cover a lot of ground. Growth hormone secretagogues, reproductive hormones, melanocortin agonists — they touch multiple endocrine systems, and each one has a distinct pharmacological profile. What follows is a breakdown of every hormonal peptide available at PeptidesDirect, with enough mechanistic detail to help you pick the right tool for your research question.
How the GH Axis Works
The Growth Hormone Signaling Cascade
The hypothalamus releases GHRH, which stimulates GH secretion from the anterior pituitary. Somatostatin, also from the hypothalamus, acts as the brake. Once GH enters circulation, the liver converts it to IGF-1, which mediates many of the downstream effects on target tissues.
Sermorelin, Tesamorelin, and CJC-1295 all act at the top of this cascade, mimicking GHRH. Ipamorelin comes in through a different door — the ghrelin receptor on pituitary somatotrophs. HGH bypasses the whole upstream pathway and delivers growth hormone directly. And IGF-LR3 skips past even that, providing the downstream growth factor without involving GH at all.
Where a peptide intervenes in this chain dictates its effects, its limitations, and what kind of research it's suited for.
HGH — Direct Growth Hormone
HGH (Human Growth Hormone, Somatotropin) is a 191-amino acid protein identical to the endogenous hormone produced by the anterior pituitary. Recombinant HGH gives you direct GH action — no reliance on secretion pathways, no pulsatility, no feedback loops to worry about.
It signals through the GH receptor via the JAK-STAT pathway, and decades of research data make it one of the best-characterized peptides in the field. If your experiment needs a known quantity of GH acting directly on target tissues, this is the straightforward choice. Particularly relevant for GH receptor signaling studies, IGF-1 induction models, GH-deficiency paradigms, and metabolic research on lipolysis and protein synthesis.
191-amino acid recombinant human growth hormone. Direct GH receptor activation via JAK-STAT pathway.
CJC-1295/Ipamorelin Mix — Dual-Pathway GH Secretion
The CJC-1295/Ipamorelin combination pairs two peptides that hit different receptors to stimulate GH release. The pharmacological rationale here is genuinely interesting.
CJC-1295 is a modified GHRH analog carrying a Drug Affinity Complex (DAC) that extends its half-life to roughly 8 days. It binds the GHRH receptor on pituitary somatotrophs and stimulates pulsatile GH release — but from the GHRH side of the equation.
Ipamorelin works the other side. It's a growth hormone releasing peptide (GHRP) that acts as an agonist at the ghrelin receptor (GHS-R1a). Among GHRPs, Ipamorelin stands out for its selectivity: unlike GHRP-6 or GHRP-2, it has minimal effects on cortisol and prolactin, and it doesn't significantly stimulate appetite.
Synergistic Dual-Receptor Activation
When you combine a GHRH analog with a GHRP, the GH response is more than additive. The two receptor systems amplify each other, producing substantially greater GH release than either peptide alone while preserving the natural pulsatile rhythm. This makes the combination especially useful for studying synergistic GH secretion mechanisms and dual-receptor activation dynamics.
Dual-pathway GH secretagogue combining GHRH analog with ghrelin receptor agonist for synergistic GH release.
Selective GHRP with minimal cortisol and prolactin effects. Clean GH release through the ghrelin receptor.
Sermorelin — The Physiological Approach
Sermorelin consists of the first 29 amino acids of the 44-amino acid GHRH molecule — the biologically active fragment. It stimulates GH release through the endogenous GHRH receptor, producing acute GH pulses that closely mirror the body's natural secretion pattern.
What makes Sermorelin particularly appealing for certain research designs is that it's self-limiting. When GH rises too high, somatostatin feedback kicks in and dampens further release. You can't easily overshoot. Sermorelin also has a historical footnote — it was FDA-approved as a diagnostic agent under the brand name Geref.
Sermorelin vs. CJC-1295: Half-Life Tradeoff
The tradeoff compared to CJC-1295 is half-life. Sermorelin clears in about 10 to 20 minutes, producing a sharp GH pulse and then fading. CJC-1295 with its DAC modification persists for roughly 8 days, creating sustained GH elevation rather than discrete pulses. The strong somatostatin feedback that follows Sermorelin is actually a feature if you're studying physiological GH dynamics, but a limitation if you need prolonged elevation.
Sermorelin is well-suited for physiological GH secretion studies, GHRH receptor pharmacology, age-related GH decline models, and diagnostic testing protocols.
GHRH(1-29) fragment producing physiological, pulsatile GH release with intact somatostatin feedback.
Tesamorelin — Targeting Visceral Fat
Tesamorelin is another GHRH analog, but with a trans-3-hexenoic acid group attached to the tyrosine at position 1. This modification improves stability. Tesamorelin is one of the few peptides that holds an actual FDA approval — it's marketed as Egrifta for HIV-associated lipodystrophy.
The clinical trial data behind Tesamorelin is focused almost entirely on visceral adipose tissue reduction. That makes it the obvious starting point for research into visceral fat metabolism, lipodystrophy models, and GH-mediated effects on fat distribution. It targets the same GHRH receptor as Sermorelin but offers a different pharmacokinetic profile thanks to its structural modification.
FDA-approved GHRH analog (Egrifta) with stabilizing modification. Primary research focus on visceral adipose tissue.
IGF-LR3 — Downstream of Everything
IGF-LR3 (Insulin-like Growth Factor 1, Long R3 variant) takes a completely different approach. Instead of stimulating GH release and waiting for the liver to produce IGF-1, it delivers a modified IGF-1 directly.
The R3 Modification
The R3 modification is what matters here: it reduces binding to IGF binding proteins (IGFBPs), which substantially increases bioavailability and extends the effective half-life. IGF-LR3 activates the IGF-1 receptor, triggering PI3K/Akt and MAPK signaling cascades. It's a potent mitogen with strong cell proliferation effects.
This peptide is the right choice when your research question is about downstream GH effects rather than GH itself — cell proliferation models, IGF-1 receptor signaling, muscle hypertrophy mechanisms, or metabolic studies where you want to isolate IGF-1 action from GH action.
Modified IGF-1 with reduced IGFBP binding. Extended half-life for cell proliferation and IGF-1 receptor studies.
HCG — Reproductive Endocrinology
HCG (Human Chorionic Gonadotropin) is structurally distinct from the other peptides on this page. It's a glycoprotein hormone composed of alpha and beta subunits, and it mimics Luteinizing Hormone (LH) by binding the LH/CG receptor.
Its primary research application is reproductive endocrinology. HCG stimulates testosterone production in Leydig cells, making it a standard tool in fertility research, testosterone synthesis studies, and LH receptor pharmacology. The compound has extensive clinical and research precedent, with well-established protocols across multiple model systems.
LH mimetic glycoprotein hormone for reproductive endocrinology, fertility research, and Leydig cell stimulation.
Melanotan 2 — Beyond Pigmentation
Melanotan 2 (MT-2) is a synthetic cyclic analog of alpha-melanocyte-stimulating hormone. It's grouped with hormonal peptides because of its endocrine effects, though it's technically a melanocortin peptide.
MT-2 is non-selective across melanocortin receptor subtypes, and this is what makes it pharmacologically interesting. Its activity at MC1R drives melanogenesis — the pigmentation pathway. But it also hits MC4R, which is involved in appetite regulation and sexual function. The cyclic structure gives it better stability than linear alpha-MSH.
Research applications span melanocortin receptor pharmacology, pigmentation biology, appetite and energy homeostasis through MC4R, sexual function, and UV protection mechanisms in skin.
Non-selective melanocortin receptor agonist. Research spans pigmentation, appetite, and sexual function pathways.
Choosing the Right Peptide for Your Research
The decision mostly comes down to where in the signaling cascade you want to intervene and what question you're trying to answer.
Thinking in Tiers for GH Axis Research
For researchers focused on the GH axis specifically, it helps to think in tiers:
- Do you want GH itself? Use HGH.
- Do you want to stimulate GH release? Then choose your receptor — GHRH pathway (Sermorelin or CJC-1295), ghrelin pathway (Ipamorelin), or both (the combination).
- Do you want the downstream growth factor without involving GH? That's IGF-LR3.
Quality and Ordering
All hormonal peptides at PeptidesDirect come with independent Janoshik COA purity verification. We ship within the EU in 2-3 days with no customs issues. Payment options include both crypto and card. Bacteriostatic water for reconstitution is also available.