Immunohistochemical Studies of Central and Peripheral Peptidergic Neurons

Publisher Summary This chapter reviews some aspects of the distribution of presently characterized neuropeptides revealed by immunohistochemical techniques. The distribution of neuropeptides as revealed by immunohistochemical techniques suggests two varieties of neural circuits in which the peptides play a role. The first of these generalized systems is thought to participate in neuroendocrine regulation, as the peptides are found in high concentrations in terminals adjacent to vascular elements that drain either to the anterior pituitary or to systemic circulation. Peptides released from such neurohemal sites may act as hormones upon target cells. Alternatively, they may act via axo-axonic interactions with other peptidergic terminals that liberate “true” hormones. Neuropeptides are also found in circuits of neurons engaged in interneuronal communication.