Some projections of dynorphin-immunoreactive neurons in the rat central nervous system

Dynorphin 1-8 (DYN 1-8) and Dynorphin B (DYN B) have been immunocytochemically localized to neuronal perikarya throughout the adult rat central nervous system (CNS). In order to determine if any DYN 1-8 and DYN B immunoreactive (DYN-I) cell bodies have long projections, indirect immunofluorescence was used in combination with injections of the fluorescent retrograde tracer, Fluoro-Gold (FG). Both DYN-I and retrogradely transported FG were found within the same neurons in the dorsal parabrachial nucleus (DPB) after FG injections in the central nucleus of the amygdala (Ce). Neurons that contain both DYN-I and FG were also found in the paraventricular nucleus, the perifornical region, the dorsal area and the lateral hypothalamus after FG injections in the upper thoracic spinal cord. These results suggest that cells that contain DYN-I have long ascending and descending projections in the rat CNS, and thus may exert widespread effects.