http://www.ncbi.nlm.nih.gov/pubmed/7515354
Galanin is a 
neuropeptide encoded by the 
GAL gene,
[1]  that is widely expressed in the brain, spinal cord, and gut of humans  as well as other mammals. Galanin signaling occurs through three 
G protein-coupled receptors.
[2]
The functional role of galanin remains largely unknown; however,  galanin is predominately involved in the modulation and inhibition of 
action potentials in 
neurons. Galanin has been implicated in many biologically diverse functions, including: 
nociception,  waking and sleep regulation, cognition, feeding, regulation of mood,  regulation of blood pressure, it also has roles in development as well  as acting as a 
trophic factor.
[3] Galanin is linked to a number of diseases including 
Alzheimer’s disease, 
epilepsy as well as 
depression, 
eating disorders and 
cancer.
[4][5] Galanin appears to have 
neuroprotective activity as its biosynthesis is increased 2-10 fold upon 
axotomy in the 
peripheral nervous system as well as when seizure activity occurs in the brain. It may also promote 
neurogenesis.
[2]
http://en.wikipedia.org/wiki/Galanin