Spexin is a neuropeptide that is conserved amongst humans and rodents. Spexin activates galanin2/3 receptors, inducing a different active conformation of GalR2 to galanin. The broad distribution of spexin suggests multiple physiological roles including as a regulating factor in obesity and energy metabolism. Spexin is ubiquitously expressed in human tissue, however, a correlation has been found with obesity and age. Obese patients had significantly lower levels of circulating spexin than those with a healthy weight range. The significance of this suggests spexin regulates appetite, feeding behaviour, and energy expenditure. Spexin also specifically inhibits the uptake of long-chain fatty acids by adipocytes.

Spexin is a central modulator of cardiovascular and renal function and can elicit central nervous system behavioural responses. As spexin levels decrease with age there is research to understand if it plays a role in age-related pathophysiology of cardiometabolic conditions. Spexin is also being considered an early biomarker for cardiovascular disease due to the magnitude with which it decreases as the pathophysiology progresses.