HIGH MOLECULAR-WEIGHT OPIOID-CONTAINING PROTEINS IN STRIATUM

Striatal extracts of guinea pigs, rats, and cattle were found to contain two large proteins (>40,000 and >100,000 daltons) that on treatment with trypsin yield opioid peptides differing chromatographically from the opioid nonapeptide generated by trypsin digestion of endorphins, β-lipotropin or pro-opiocortin. Furthermore, the large opioid proteins found in the pituitary do not appear to be present in the striatum. These and other findings indicate that the striatal enkephalins are produced via a pathway that differs from the one deduced from studies on the pituitary.