Neuropeptide W-23

Where it comes from

Made in

The brainstem (periaqueductal grey), the hypothalamus, and the gastrin cells of the stomach’s antrum

Sent out by

Fasting lowers it in the stomach, and refeeding raises it again

Acts on

• Hypothalamic feeding circuits
• Stress axis
• Pain circuits
• Fat cells

What it does

• Reports on feeding conflict: one laboratory found injection into the brain suppressed food intake ², another that it raised it ³
• Releases prolactin and corticosterone, and raises body temperature and energy use ²
• Male mice lacking its receptor grow obese in adulthood ⁴

In medicine

• No medicine copies it or blocks it, and it is not measured in people
• Its receptors have no ligands in clinical use, so nothing can act on NPBWR1 or NPBWR2 at all ¹

Beyond the body’s own use

• Nothing containing it is in trials, approved or obtainable outside the laboratory
• The feeding evidence points both ways and has not been resolved: injected into the brain of a rat it reduced food intake in one laboratory’s hands ² and increased it in another’s, where the injection went into the paraventricular nucleus ³. Dose and site differ between the two
• What is clearer is the receptor rather than the peptide: mice lacking NPBWR1 become obese in adulthood, which says the system restrains weight without saying which of its two peptides does it ⁴