Immunocytochemical localization of neuropeptides in the adrenal medulla

The distribution of neuropeptides exhibits pronounced interspecies heterogeneity. Neuropeptides may function as hormones secreted from chromaffin cells or as neurotransmitters/neuromodulators released from nerve terminals. However, other possible functions such as trophic or intracellular effects should also be considered. Thus, to understand the role of neuropeptides, it is important to explore their localization in different species. The distribution of enkephalins, neurotensin, neuropeptide Y, calcitonin gene-related peptide, and galanin in the adrenal medulla of rat, cat, hamster, and mouse is presented in detail.