5108314419ENSG00000069482ENSMUSG00000024907P22466P47212NM_015973NM_010253NM_001329667NP_057057NP_001316596NP_034383Galanin is a neuropeptide encoded by the GAL gene,[5] that is widely expressed in the brain, spinal cord, and gut of humans as well as other mammals.

Galanin is often co-localized with classical neurotransmitters such as acetylcholine, serotonin, and norepinephrine, and also with other neuromodulators such as neuropeptide Y, substance P, and vasoactive intestinal peptide.

[12] Galanin was first identified from porcine intestinal extracts in 1978 by Professor Viktor Mutt and colleagues at the Karolinska Institute, Sweden[13] using a chemical assay technique that detects peptides according to its C-terminal alanine amide structure.

Within the central nervous system, highest concentrations are found in the hypothalamus, with lower levels in the cortex and brainstem.

[16] Gastrointestinal galanin is most abundant in the duodenum, with lower concentrations in the stomach, small intestine, and colon.

[6] Injections of galanin into the lateral ventricle or directly into the hypothalamus creates the urge to feed, with a preference for eating fats.

[19] Galanin also regulates glucose metabolism and can potentially alleviate symptoms of Diabetes Type II due to its interaction with insulin resistance.

[24] One of the pathological features of the brain in the later stages of Alzheimer's disease is the presence of overgrown GAL-containing fibres innervating the surviving cholinergic neurons.

[6][25] A second hypothesis has been generated based on data that suggest GAL is involved in protecting the hippocampus from excitotoxic damage and the neurons in the cholinergic basal forebrain from amyloid toxicity.

[15] Currently, one of the potential mechanisms for this is that galanin stimulates the hypothalamus-pituitary-adrenal axis, which leads to an increase in glucocorticoid secretion.

[32][33] It has been shown that galanin plays a role in the control of the early post-natal neural development of the dorsal root ganglion (DRG).

[19] GalR2 activation is believed to mediate the survival role galanin plays in the dorsal root ganglion.

[34] Galanin-expressing neurons in the medial preoptic area of the brain are responsible for regulating aggression towards pups by male mice.

Estrogen and progesterone genomic receptors in galanin (Gal)-expressing neurons control discrete aspected of plasticity.