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Ghrelin and Its Receptor Are Found Throughout the Human Body, Not Just the Stomach and Brain

RPEP-007312002Gnanapavan, Sharmilee; Kola, Blerina; Bustin, Stephen A; Morris, Damian G; McGee, Patrick; Fairclough, Peter; Bhattacharya, Satya; Carpenter, Robert; Grossman, Ashley B; Korbonits, Márta
In VitroModerate evidence
The takeaway

Ghrelin mRNA and both GHS-R subtypes (1a and 1b) were detected in a wide range of human tissues including heart, lung, kidney, liver, and immune cells, far beyond the stomach-brain axis.

Every major organ

Ghrelin mRNA and/or its receptors detected in stomach, intestine, heart, lung, kidney, liver, pancreas, and immune cells — truly body-wide

What the researchers found

Ghrelin mRNA was detected in stomach (highest), intestine, pancreas, kidney, and other tissues, while GHS-R1a and GHS-R1b showed distinct but overlapping tissue distributions across virtually all major human organs.

Why it matters

The widespread tissue expression explains why ghrelin affects so many body systems. For drug development, it means GH secretagogues will have multi-organ effects that must be anticipated and managed.

How the study worked

In-vitro tissue distribution study using RT-PCR to detect ghrelin, GHS-R1a, and GHS-R1b mRNA expression across a panel of human tissues and cell types.

What this study cannot tell us

mRNA detection doesn't prove functional protein expression. RT-PCR can detect low-level expression that may not be physiologically relevant. Human tissue availability limits sample sizes.

How to read the evidence

Moderate evidence from comprehensive tissue distribution mapping in human tissues, though limited to mRNA detection.

When this study was published

Published in 2002. Widespread ghrelin/GHS-R tissue expression has been confirmed at protein level in subsequent studies.

The bigger picture

Ghrelin isn't a stomach hormone with distant effects — it's part of a body-wide signaling network with local production and action in every major organ system.

Questions still open

  • Does local ghrelin production in each tissue serve tissue-specific functions?
  • Is GHS-R1b's widespread expression functionally important?
  • Could tissue-specific ghrelin actions be targeted independently?

Common questions

Is ghrelin just a stomach hormone?
No. While the stomach is the main source, ghrelin mRNA is also found in the intestine, pancreas, kidney, heart, lung, and immune cells. It's a body-wide signaling system, not just a stomach hormone.
Why does this matter for GH peptide users?
Because ghrelin receptors are in so many tissues, GH secretagogues don't just affect GH and appetite — they can potentially affect the heart, kidneys, pancreas, lungs, and immune system. This widespread receptor presence explains the diverse effects and side effects of these compounds.

Read the original research

The tissue distribution of the mRNA of ghrelin and subtypes of its receptor, GHS-R, in humans.

The Journal of clinical endocrinology and metabolism, 87(6), 2988

View on PubMed ↗

Citation

Gnanapavan, Sharmilee; Kola, Blerina; Bustin, Stephen A; Morris, Damian G; McGee, Patrick; Fairclough, Peter; Bhattacharya, Satya; Carpenter, Robert; Grossman, Ashley B; Korbonits, Márta. (2002). The tissue distribution of the mRNA of ghrelin and subtypes of its receptor, GHS-R, in humans.. The Journal of clinical endocrinology and metabolism, 87(6), 2988.