Prodynorphin peptide immunocytochemistry in rhesus monkey brain

The present study describes the immunocytochemical distribution of peptides derived from the prodynorphin precursor in the brain of the rhesus monkey (Macaca mulatta). Animals were treated with colchicine (intracerebroventricularly) prior to perfusion to enhance the observation of perikaryal immunoreactivity. Using antisera generated against dynorphin A(1-17), dynorphin B(1-13), and prodynorphin(186-208) (or bridge peptide), the anatomical distribution of dynorphin systems was mapped. The results indicate a widespread neuronal localization of immunoreactivity from the cerebral cortex to the caudal medulla. Anti-dynorphin B and anti-bridge peptide sera proved useful for the demonstration of neuronal perikarya, while the dynorphin A antiserum was best for localizing terminal projection fields. Immunoreactive perikarya are located in numerous brain loci, including the cingulate cortex, caudate nucleus, amygdala, hypothalamus (especially the magnocellular nuclei), thalamus, substantia grisea centralis, parabrachial nucleus, nucleus tractus solitarius, and other nuclei. In addition, fiber and terminal immunoreactivity are seen in varying densities in the striatum and pallidum, substantia innominata, hypothalamus, substantia nigra pars reticulata, parabrachial nucleus, spinal trigeminal nucleus, and other areas. The distribution of prodynorphin peptides in the brain of the monkey is similar to that described for the rat brain; however, significant differences also exist. Other interspecies differences in the anatomy of prodynorphin and proenkephalin neuronal systems in the monkey and human brain are further discussed.