[5][6] The 105 amino acid residue human precortistatin in turn is cleaved into cortistatin-17 and cortistatin-29.

[5] Cortistatin (or more specifically cortistatin-17) is a neuropeptide that is expressed in inhibitory neurons of the cerebral cortex, and which has a strong structural similarity to somatostatin.

Unlike somatostatin, when infused into the brain, it enhances slow-wave sleep.

Cortistatin is a neuropeptide with strong structural similarity to somatostatin (both peptides belong to the same family).

However, it also has many properties distinct from somatostatin, such as induction of slow-wave sleep, apparently by antagonism of the excitatory effects of acetylcholine on the cortex, reduction of locomotor activity, and activation of cation selective currents not responsive to somatostatin.