CLIP

Where it comes from

Made in

The pituitary’s intermediate lobe (vestigial in adults), hypothalamic POMC neurons, and skin

Sent out by

With alpha-MSH, to which it is the other half

Acts on

• Pancreatic islets (insulin release, in animals)
• Brain (sleep)

What it does

• A fragment of it, ACTH 22-39, was isolated from obese mice as an insulin secretagogue and named beta-cell-tropin ¹
• Given into the rat brain it lengthens REM sleep, an effect that persists after the pituitary is removed ²
• Its presence marks that POMC was cut the intermediate-lobe way, yielding alpha-MSH and CLIP rather than ACTH ³

In medicine

• None of its own; there is no clinical assay for CLIP, and whether an ACTH antibody detects it depends on which end of the molecule that antibody recognises
• Which cells make it is the clinical point rather than any action: CLIP marks the intermediate-lobe route of POMC processing ³

Beyond the body’s own use

• There is no CLIP product and no human trial; everything claimed for it rests on two old animal findings
• The insulin one is the stronger: ACTH 22-39 behaved identically to the natural beta-cell-tropin of obese mice and potentiated glucose-driven insulin release ¹
• The sleep one is thinner: ten nanograms of CLIP into the rat brain increased paradoxical sleep, and nothing comparable has been attempted in people ²
• What is unknown is whether CLIP has a receptor at all; it does not activate the melanocortin receptors and no other has been identified for it