Galanin is a neuropeptide synthesised and released by the brainstem locus coeruleus (LC). Galanin is expressed in most LC neurons in rodents and humans. Galanin has been shown to inhibit LC activity by hyperpolarising LC neurons, suppressing their spontaneous firing rate, and enhancing α2-adrenergic receptor-mediated negative feedback. Galanin is also a potent trophic and neuroprotective factor throughout the nervous system.

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, these G protein-coupled receptors are 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 with epilepsy.

N-terminal fragments naturally occur in vivo, but their relevance is unclear. Some N-terminal fragments reduce metabolic and functional disorders in experimental heart damage. Using N-terminal fragments such as galanin (3-13) can clarify the function of full-length galanin during myocardial ischemia and reperfusion injury. This may highlight new agonists/antagonists for the galanin GalR receptors that can be putative therapeutic targets.