N Immunocytochemical Mapping of Methionine- Nkephalin-arg-gly-leu in the Human Brainstem

bstract—Using an indirect immunoperoxidase technique, e studied the distribution of immunoreactive fibers and cell odies containing methionine-enkephalin-Arg-Gly-Leu in he adult human brainstem. Immunoreactive cell bodies were ound in the reticular formation of the medulla oblongata (in hich we observed the highest density of immunoreactive ell bodies) and the pons, the solitary nucleus, the hypoglosal nucleus, the medial and spinal vestibular nuclei, the latral cuneate nucleus, the nucleus prepositus, the central ray of the pons and mesencephalon, the central and perientral nuclei of the inferior colliculus, the superior collicuus, ventral to the superior olive and in the midline region of he pons and mesencephalon. The highest density of immuoreactive fibers containing methionine-enkephalin-Argly-Leu was found in the spinal trigeminal nucleus, the entral gray and the reticular formation of the medulla oblonata, pons and mesencephalon, the solitary nucleus, the pinal vestibular nucleus, the dorsal accessory olivary nuleus, the raphe obscurus, the substantia nigra and in the nterpeduncular nucleus. The widespread distribution of imunoreactive structures containing methionine-enkephalinrg-Gly-Leu in the human brainstem indicates that this europeptide might be involved in several physiological echanisms, acting as a neurotransmitter and/or euromodulator. © 2004 IBRO. Published by Elsevier Ltd. All ights reserved.