How the GH Axis Works: GHRH → Pituitary → GH → IGF-1

The GH axis is a multi-level endocrine system. To read the literature correctly, it is important to distinguish the signal from the hypothalamus, the pituitary response and the peripheral effects associated with IGF-1.

1. The hypothalamus and GHRH

GHRH is one of the main stimulatory signals to the pituitary somatotrophs. Activation of the GHRH receptor increases signalling that can trigger growth hormone release.

2. The pituitary and GH

The anterior pituitary releases GH in pulses. This pattern is influenced by GHRH, somatostatin, ghrelin/GHS signalling and other physiological factors.

3. Peripheral signalling and IGF-1

GH acts on several tissues, including the liver, where it can stimulate IGF-1 synthesis. GH and IGF-1 are therefore linked, but they are not the same molecule nor the same point in the signalling pathway.

Where research compounds fit

Why it matters to distinguish levels of the axis

Comparisons such as CJC-1295 vs Ipamorelin, Sermorelin vs Tesamorelin or GH vs IGF-1 are often read as if they were at the same level of the system. This overview connects these categories and helps avoid mixing up mechanisms when reading the literature.

More detailed guides

• GHRH analogues vs GH secretagogues
• CJC-1295 No DAC vs Ipamorelin
• Sermorelin vs Tesamorelin
• GHRP-2 vs GHRP-6

This content is intended for education and understanding of the scientific literature. It does not constitute medical advice or instructions for use.