Galanin is widely distributed in the central nervous, peripheral, and endocrine systems. Galanin’s overarching function is as an inhibitory, hyper-polarizing neuromodulator for classical neurotransmitters like acetylcholine and serotonin. Galanin interacts with 3 receptor subtypes, GalR1-3 G protein-coupled receptors inserted into the plasma membrane. GalR1 is believed to activate a Gβγ pathway to regulate MAPK activation. GalR2 can also activate the MAPK pathway, but unlike GalR1, there is detectable inositol phosphate production. GalR3 is associated with the Gαi/o pathway. Activation of the receptor leads to a cellular influx of K+. Each receptor has been associated with neurological diseases such as GalR3 and epilepsy.

Galanin is a key regulator of growth hormone and insulin release and adrenal secretion however the role galanin plays is not clear. Administration of galanin to animal models leads to inhibition of insulin secretion but this is not replicated in humans.

N-terminal galanin fragments naturally occur in vivo, but their relevance is unclear. Some N-terminal fragments reduce metabolic and functional disorders in experimental heart damage. Their relative abundance varies, with fragment (13-20) being one of the lowest quantities detected. The physiological relevance of the galanin fragment (13-20) and its affinity to the various Gal receptors has yet to be made clear. Binding assays and displacement assays in rat brain tissue have been performed with similar N-terminal galanin fragments to try and elucidate their function. Using N-terminal fragments such as galanin (13-20) can help clarify the role of full-length galanin in various roles, such as during myocardial ischemia and reperfusion injury. This may highlight new agonists/antagonists for the galanin GalR receptors that can be therapeutic targets.