Cholecystokinin in the rat spinal cord: distribution and lack of effect of neonatal capsaicin treatment and rhizotomy.

The distribution of cholecystokinin (CCK) and gastrin-like immunoreactivities in rat spinal cord and spinal roots was studied with two sequence-specific radioimmunoassays. No gastrin was found in the cord or in spinal roots or sensory ganglia, however CCK was present at all levels of the cord and was concentrated in the dorsal horn. No CCK was found in sensory roots. Neonatal capsaicin treatment had no effect on ventral cord CCK and caused a small increase in dorsal cord levels. Neither dorsal rhizotomy nor combined dorsal and ventral rhizotomy affected CCK levels in either dorsal or ventral cord. These results indicate that most of the CCK in the rat spinal cord is not present in the terminals of primary afferent fibers.