Ipamorelin and CJC-1295: GH secretagogues in research

Ipamorelin and CJC-1295 are among the most discussed compounds in the research literature on growth hormone (GH) secretagogues. Both act on the pituitary gland, but they do so through different pathways. This overview explains how their receptors differ, what has been observed in in vitro and animal model studies, and how laboratories work with these research reagents in practice.

We write only about research reagents. We do not describe any use in humans or animals.

Two pathways that drive GH release

GH release from the pituitary is governed by two main signals. The first comes from growth hormone releasing hormone (GHRH), which acts on the GHRH receptor (GHRH-R). The second comes from the GHRP family of secretagogues, which bind the GHS-R1a receptor, also known as the ghrelin receptor.

The GHRH-R receptor

GHRH-R sits on the somatotroph cells of the pituitary. Its activation triggers a cAMP-dependent pathway that leads to the release of stored GH. The literature describes this route as the physiological regulator of hormone secretion.

The GHS-R1a receptor

GHS-R1a couples mainly to the Gq protein. Its activation switches on phospholipase C and raises intracellular calcium. The receptor is found in the pituitary and in the hypothalamus. In vitro studies have reported that the two pathways can reinforce each other. This synergy is one reason why research designs often compare GHRH and GHRP signals side by side.

Ipamorelin: selectivity in the literature

Ipamorelin is a pentapeptide with the sequence Aib-His-D-2Nal-D-Phe-Lys-NH2. It is a synthetic GHS-R1a agonist. Its short structure makes synthesis and purity control straightforward. Compared with the earlier hexapeptide GHRP-6, animal model studies have described a smaller effect on cortisol and prolactin. This selectivity is the feature most often discussed when researchers evaluate ipamorelin.

Selectivity is an observation tied to specific models, not a universal property of the molecule. Each study has its own conditions, species and measurement methods. When planning an experiment, read the original papers rather than summaries.

CJC-1295: modification and the DAC technology

CJC-1295 is a GHRH analogue built on the 1-29 fragment. Amino acid substitutions were introduced to increase resistance to peptide-degrading enzymes, including dipeptidyl peptidase IV (DPP-IV). As a result, the molecule keeps its structure under experimental conditions for longer than native GHRH.

The no DAC version

The no DAC variant has no additional linker, so its time in the experimental system is short. In the literature it is described as a tool for observing brief, pulse-like responses, similar to the physiological rhythm of GH secretion.

The DAC version

DAC, short for Drug Affinity Complex, is a chemical moiety attached to the molecule. Inside a biological system it binds albumin, the main protein of blood plasma. This complex extends the time the peptide remains in circulation and changes the response profile compared with the no DAC version. For that reason, the two variants are considered separately in research projects, and the choice depends on the question being asked.

Sermorelin as GHRH (1-29)

Sermorelin is the fragment of GHRH that contains the first 29 amino acid residues of the natural molecule. This shorter part retains full activity at GHRH-R. The peptide was once available as a prescription drug for diagnostic use, and today it remains a useful reference point in comparative studies. It carries no modifications designed to extend its action, which makes it a clean model of a classic, short GHRH signal.

Comparison table

Feature	Ipamorelin	CJC-1295 no DAC	CJC-1295 with DAC	Sermorelin
Compound class	GHRP-type secretagogue	GHRH analogue	GHRH analogue with DAC complex	GHRH 1-29 fragment
Target receptor	GHS-R1a	GHRH-R	GHRH-R	GHRH-R
Structural change	Aib-His-D-2Nal-D-Phe-Lys-NH2 sequence	Amino acid substitutions	Substitutions and DAC linker	None relative to the natural 1-29 sequence
Time in the experimental system	Short	Short	Extended	Short
Typical research focus	Selectivity, synergy with GHRH	Brief, pulsatile responses	Longer observation windows	Reference point

Laboratory practice

Research material usually arrives as a lyophilised powder, the dry solid left after freeze-drying. How it is handled affects how repeatable your results are, so a few basic habits are worth knowing.

Reconstitution and storage

Reconstitution means preparing a solution from the lyophilised material with bacteriostatic water or another solvent that suits your experimental plan. Work under clean conditions, add the solvent slowly down the wall of the vial, and avoid vigorous shaking. Keep the lyophilised powder cold and away from light. Working solutions should be refrigerated and labelled with the date of preparation. A concentration calculator makes it easy to work out the working concentration.

Purity analysis

Check the purity confirmed by HPLC, which for our compounds is at least 99 percent. Mass is confirmed by mass spectrometry (MS). Comparing the MS result with the theoretical mass of the sequence helps you tell a correct compound from one that is contaminated or does not match its description. You can read more on our quality page.

How to choose research material

All four compounds in this overview are available in the shop as research reagents: ipamorelin, CJC-1295 no DAC, CJC-1295 with DAC and sermorelin. Let your research question guide the choice. If you need a short, pulse-like signal, start with the no DAC variant. If you need a longer observation window, look at the DAC version. Sermorelin is a useful comparator in most designs.

Orders placed by 14:00 on a working day ship the same day. In Poland, the parcel reaches an InPost Parcel Locker (Paczkomat) the next working day. Across Europe, DPD courier delivers in 2-4 working days. Shipping is free from 75 EUR, 65 GBP or 80 USD.

Key takeaways

• Ipamorelin acts on GHS-R1a, while CJC-1295 and sermorelin act on GHRH-R.
• In research, ipamorelin is described as a selective secretagogue, although the result depends on the model.
• DAC extends the time CJC-1295 stays in the experimental system because it binds albumin.
• Sermorelin is the GHRH 1-29 fragment and a useful reference in comparisons.
• Always check the HPLC purity and MS mass before starting work.