What is the dosing range for Ghrelin?

Ghrelin is typically dosed at 0.5mcg/kg (low), 1mcg/kg (moderate), or 2mcg/kg (high) mcg/kg, administered IV or SC bolus; endogenous levels peak pre-meal. These ranges are aggregated from preclinical research and community protocols — not medical dosing guidance.

What are the reported side effects of Ghrelin?

Reported side effects of Ghrelin include: Appetite stimulation, Transient hyperglycemia, Water retention, GH pulse stimulation, Increased fat storage (chronic elevation).

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Ghrelin

Also known as: GHRL, growth hormone-releasing peptide endogenous, ghrelinergic peptide, acyl ghrelin

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Ghrelin is a research compound. Not approved for human therapeutic use outside specific investigational contexts.

📚 Content aggregated from:2 peer-reviewed sources·r/Peptides community·PubMed / NCBI

Overview

Endogenous 28-amino acid peptide secreted primarily by the stomach that functions as both the primary hunger signal and a potent growth hormone secretagogue. The n-octanoyl modification at Ser-3 (acylated form) is required for GHS-R1a receptor binding and GH-stimulating activity. Understanding ghrelin explains the mechanism behind the entire GHRP class of research peptides.

Research Summary

Ghrelin was discovered in 1999 as the endogenous ligand for the GHS-R1a receptor. Its acylated form activates GH release from the pituitary, stimulates appetite via NPY/AgRP hypothalamic neurons, and modulates energy homeostasis and fat storage. The des-acyl form (majority of circulating ghrelin) lacks GHS-R1a activity but has independent cardiovascular and cellular effects.

Dosing Range

low

0.5mcg/kg

moderate

1mcg/kg

high

2mcg/kg

Units: mcg/kg · Frequency: IV or SC bolus; endogenous levels peak pre-meal

Dosing ranges are aggregated from preclinical research and community protocols. Not medical dosing guidance.

Administration Routes

Intravenous (research)Subcutaneous injection

Reconstitution Notes

Reconstitute acylated ghrelin carefully — the n-octanoyl modification at Ser-3 is chemically labile. Use sterile water; keep at -20°C for long-term storage. Avoid repeated freeze-thaw cycles. Use within 24h once thawed.

Step-by-step reconstitution guide →

Supplies you'll need

Insulin Syringes (U-100)Reconstitution Needles Lambda BAC Water Alcohol Prep Pads

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Reported Side Effects

Appetite stimulation
Transient hyperglycemia
Water retention
GH pulse stimulation
Increased fat storage (chronic elevation)

Research Papers

2 peer-reviewed sources

Ghrelin is a growth-hormone-releasing acylated peptide from stomach

Nature1999

The role of ghrelin in energy balance and growth hormone secretion

Journal of Clinical Endocrinology & Metabolism2001

Community Experiences

Aggregated from public forums. Anecdotal — not clinical evidence.

r/Peptides

Community discussion of ghrelin's role in understanding GHRP mechanisms and appetite effects.

View original thread

r/science

Scientific discussions on ghrelin's role in metabolism and hunger signaling.

View original thread

Overview

Ghrelin is one of the most important peptide hormones discovered in the past three decades. Its identification in 1999 by Kojima and colleagues at Curran & Genentech/Osaka University fundamentally reframed understanding of appetite and growth hormone regulation.

Before ghrelin's discovery, researchers knew the GHS-R1a receptor existed (it was the target of synthetic GHRP research compounds) but didn't know the endogenous ligand. Ghrelin was that missing ligand — produced primarily by X/A-like cells in the gastric fundus and secreted in pulses that rise pre-meal and fall post-meal.

Mechanism

The Acylation Requirement

The unique feature of ghrelin is its post-translational modification: an n-octanoyl (C8:0) group attached to the hydroxyl group of serine at position 3. This acylation is catalyzed by ghrelin O-acyltransferase (GOAT) and is absolutely required for GHS-R1a binding.

Acyl ghrelin (active): ~20% of circulating ghrelin; binds GHS-R1a → GH release + appetite
Des-acyl ghrelin (inactive at GHS-R1a): ~80% of circulating ghrelin; has independent effects via unknown receptors

GH Secretion Pathway

Acyl ghrelin binds GHS-R1a in the hypothalamus and anterior pituitary
In the hypothalamus: stimulates GHRH release and inhibits somatostatin (removing GH's primary brake)
Direct pituitary action: activates somatotrophs to release GH in pulses
GH → liver → IGF-1 production

Appetite Regulation

Ghrelin activates NPY (neuropeptide Y) and AgRP (agouti-related peptide) neurons in the arcuate nucleus of the hypothalamus — the primary orexigenic (appetite-stimulating) circuit. This is why all GHS-R1a agonists (GHRP-6, MK-677, ipamorelin) stimulate appetite to varying degrees.

Ghrelin and the GHRP Class

Understanding ghrelin clarifies why different GHRPs have different appetite profiles:

| Compound | GHS-R1a affinity | Appetite effect | |----------|-----------------|-----------------| | Ghrelin | Native ligand | Strong | | GHRP-6 | High | Strong | | MK-677 | High | Strong | | GHRP-2 | High | Moderate | | Ipamorelin | Selective | Mild |

Ipamorelin's lower appetite drive reflects its more selective receptor engagement profile — it doesn't fully activate all the downstream pathways that full GHS-R1a agonists like ghrelin trigger.

Research Context

Ghrelin itself is rarely used as a research peptide in the way synthetic GHRPs are — its instability (the acyl group hydrolyzes readily), very short half-life, and the availability of stable synthetic analogues make it more valuable as a reference standard than a research tool. Its main importance is mechanistic: understanding ghrelin is foundational to understanding the entire GH secretagogue field.