Immunohistochemical localization of enkephalin in rat brain and spinal cord

Madhabananda Sar*, Walter E. Stumpf, Richard J. Miller, Kwen‐Jen ‐J Chang, Pedro Cuatrecasas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

690 Scopus citations


The distribution of immunoreactive enkephalin in rat brain and spinal cord was studied by immunoperoxidase staining using antiserum to leucine‐enkephalin ([Leu5]‐enkephalin) or methionine‐enkephalin ([Met5]‐enkephalin). Immunoreactive staining for both enkephalins was similarly observed in nerve fibers, terminals and cell bodies in many regions of the central nervous system. Staining of perikarya was detected in hypophysectomized rats or colchicine pretretated rats. The regions of localization for enkephalin fibers and terminals include in the forebrain: lateral septum, central nucleus of the amygdala, area CA2 of the hippocampus, certain regions of the cortex, corpus striatum, bed nucleus of the stria terminalis, hypothalamus including median eminence, thalamus and subthalamus; in the midbrain: nucleus interpeduncularis, periaqueductal gray and reticular formation; in the hind brain: nucleus parabrachialis, locus ceruleus, nuclei raphes, nucleus cochlearis, nuclear tractus solitarii, nucleus spinalis nervi trigemini, motor nuclei of certain cranial nerves, nucleus commissuralis and formatio reticularis; and in the spinal cord the substantia gelatinosa. In contrast enkephalin cell bodies appear sparsely distributed in the telencephalon, diencephelon, mensencephalon and rhombencephalon. The results of the histochemical staining show that certain structures which positively stain for enkephalin closely correspond to the distribution of opiate receptors in the brain and thus support the concept that the endogenous opiate peptides are involved in the perception of pain and analgesia. The localization of enkephalin in the preoptic‐hypothalamic region together with the presence of enkephalin perikarya in the paraventricular and supraoptic nuclei suggest a role of enkephalin in the regulation of neuroendocrine functions.

Original languageEnglish (US)
Pages (from-to)17-37
Number of pages21
JournalJournal of Comparative Neurology
Issue number1
StatePublished - Nov 1 1978

ASJC Scopus subject areas

  • General Neuroscience


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