Dynorphin

[[BioPsy}}

Dynorphin is a class of peptides produced by many different populations of neurons, which has some opiate-like activity. It is thus classed as an endogenous opioid peptide. Dynorphin functions primarily as a kappa opioid receptor agonist, meaning that it acts mainly at kappa opioid receptors. Other opioid peptides include beta-endorphin, [met]-enkephalin, [leu]-enkephalin and endomorphin. The dynorphins, which include dynorphin A, dynorphin B, alpha- and beta-neoendorphin, and big dynorphin, are all the products of a single gene, 'preprodynorphin'. It was discovered in the early 1980's by Charles Chavkin, then a researcher in the laboratory of Avram Goldstein, one of the founders of the field of research focused on the endogenous opioids.

Dynorphin is produced in many different parts of the brain, including the hypothalamus, the hippocampus and the spinal cord, and has many different physiological actions, depending upon its site of production. For example, dynorphin that is made in magnocellular vasopressin neurons of the supraoptic nucleus is important in the patterning of electrical activity. Dynorphin produced in magnocellular oxytocin neurons is a negative feedback inhibitor of oxytocin secretion. Dynorphin produced in the arcuate nucleus and in orexin neurons of the lateral hypothalamus affects the control of appetite.

Dynorphin may act as an antidote to pleasurable effects of cocaine. As such, it may help some individuals against addiction. Blocking dynorphin may help alleviate depression.