Sources of neostriatal cholecystokinin in the cat

The objective of this study was to determine the sources of cholecystokinin within the neostriatum of the cat. Cholecystokinin-immunoreactive cells and fibers were detected by means of the peroxidase antiperoxidase immunohistochemical technique. This method was combined with intrastriatal injections of the retrograde marker horseradish peroxidase conjugated with wheat-germ agglutinin to survey the possible afferent sources of cholecystokinin to the feline neostriatum. Intrinsic, apparently aspiny cholecystokinin-immunoreactive neurons organized in a pericapsular pattern were found within both the caudate and putamen of the cat. In addition, both thalamostriatal and mesostriatal projections containing cholecystokinin were observed. These results indicate that cholecystokinin within the neostriatum of the cat arises from both intrinsic and extrinsic sites.