Growth Hormone Axis research peptides

The short version

AJW Peptides is a reading desk, not a store. It covers what the peer-reviewed literature actually says about two research peptides that come up whenever people talk about the growth hormone axis: CJC-1295 and sermorelin. A peptide is a short chain of amino acids — the same building blocks as proteins, just smaller. These two are GHRH analogs, meaning they are built to mimic the body's own growth-hormone-releasing hormone (GHRH), which is the signal that tells the pituitary gland to release growth hormone (GH). When GH goes up, the liver produces more IGF-1, and that combination drives effects on body composition, recovery, and metabolism that researchers have studied for decades.

This desk does one job: it tells you, in plain language and with citations, what each peptide was tested on, in which species, and how far that evidence really reaches. Neither is a weight-loss product. Neither is a muscle pill. One never reached FDA approval; the other did and was commercially withdrawn years ago. We do not sell anything, we do not give medical advice, and we never list a human dose.

What are research peptides?

Hormones, enzymes, and signaling proteins in the body are long chains of amino acids folded into specific shapes. A peptide is a much shorter chain of the same amino acids — sometimes fewer than thirty links. Because they are short and structurally precise, peptides can bind to specific receptors on cells and switch certain processes on or off.

A research peptide is one that has been synthesized and studied in the laboratory — in cell cultures, animals, occasionally in early human trials — but has not been approved by a regulator as a medicine, or (in sermorelin's case) was approved and later withdrawn from the commercial market. Sellers describe these compounds as being for laboratory or research use only. That framing is not a legal technicality; it reflects the state of the evidence. When this site reports a number from a study — for example, a 2- to 10-fold increase in mean plasma GH in healthy adults — it reports it the way the study did, never as a target or recommendation.

How CJC-1295 and sermorelin relate on the GH axis

Both peptides work by binding the same receptor — the GHRH receptor on the anterior pituitary — and telling somatotroph cells to release the body's own GH in its natural pulsatile pattern. Neither injects exogenous GH; both act upstream of it. That is their shared pharmacological logic, and a 2025 Nature Reviews Endocrinology review synthesizes the biology and therapeutic landscape for this entire analog class ^[1].

Where they differ sharply is half-life and regulatory history. Sermorelin is the bare 29-amino-acid N-terminal fragment of endogenous GHRH — the shortest piece that retains full GHRH activity. It is short-lived (minutes to low hours), preserves physiologic pulsatile GH secretion, and has actual clinical trial data behind it from its approved-drug era ^[11]. CJC-1295 adds four amino-acid substitutions and, in its DAC variant, a covalent albumin-binding handle that extends its half-life to roughly 5-8 days — which means sustained, non-pulsatile GH and IGF-1 elevation from a single dose ^[4][7]. That prolonged elevation is both the pharmacological point and a source of the compound's main concerns. Compare these peptides side by side.

A note on how this desk reads the literature

AJW Peptides is a cross-referenced literature digest. Every claim is cited by number, and every number resolves to the shared references list. Where evidence is thin, single-species, or short-term, we say so plainly. Where safety concerns exist — and they do for both peptides — we report them from the cited literature, not from clinic marketing. We do not recommend, prescribe, or sell. The aim is a clear-eyed account of what the published science says, including its limits.