CHROMATOGRAPHIC ANALYSIS OF THE ENKEPHALIN IMMUNOREACTIVITY IN THE NUCLEUS LOCUS-CERULEUS OF THE CAT AFTER LOCAL COLCHICINE ADMINISTRATION

Cell bodies immunoreactive for methionine- and leucine-enkephalin are found in the area of the locus coeruleus (dorsolateral pons) of the ca t after injection of colchicine in the ascending projections of the nu cleus. Using radioimmunoassay procedures, it is shown that colchicine induces a significant increase in methionine- and leucine-enkephalin-i mmunoreactive material in this area of the brain. High pressure liquid chromatography analysis demonstrated that the immunoreactive material s were authentic methionine- and leucine-enkephalin. The methionine- a nd leucine-enkephalin patterns were identical in the colchicine inject ed and non-injected sides of the dorsolateral pons. It is suggested th at, in this area of the brain, colchicine (i) does not significantly m odify the processing of proenkephalin to form the pentapeptides methio nine- and leucine-enkephalin, and (ii) does not induce the appearance of new substances reactive to the enkephalin antisera employed.