THE DISTRIBUTION AND CHROMATOGRAPHIC CHARACTERIZATION OF AN AMINO-TERMINAL FRAGMENT OF CHOLECYSTOKININ (CCK)-58 IN RAT-BRAIN

Utilizing a specific antiserum against [cholecystokinin] CCK 58, a single immunoreactive peptide of .beta. 1750 daltons was detected in rat brain extracts. It is distributed in all rat brain regions containing CCK 8, though it is most abundant in areas where CCK terminals predominate (septum, striatum and olfactory tubercle/nucleus accumbens). Based on its MW, it is probably the amino terminal portion of CCK 58 left when CCK 39 is cleaved, and it may represent an intermediate in the processing of pre-pro-CCK. The presence of this peptide in CCK terminal areas implies that the proteolytic cleavage of CCK 58 occurs late in the processing, possibly in synaptic vesicles. This peptide may be released along with CCK 8 and exert an influence on synaptic transmission.