Immunoreactive dynorphin in pituitary and brain.

Abstract

Distribution of the potent opioid peptide dynorphin was determined in pituitary gland (pig, beef, rat), in the various regions, of rat brain, and in rat spinal cord, by using a highly specific antiserum. By gel permeation chromatography in 4 M guanidine, the porcine pituitary immunoreactivity is found in a major peak of apparent MW .apprx. 1700 and a minor peak of .apprx. 3400. Similar peaks are found in rat pituitary extracts, whereas rat brain contains, in addition, 2 peaks of larger apparent MW. In the pituitary, immunoreactive dynorphin is found predominantly in pars nervosa. In the CNS, it is distributed widely, with highest concentrations in hypothalamus, medulla-pons, midbrain and spinal cord. Although dynorphin contains leucine-enkephalin, the regional distribution of dynorphin is different from that of enkephalin or of any other known opioid peptide.