The distribution of PHI-like immunoreactivity in the rat central nervous system

Abstract

Histochemical localization of peptide histidine isoleucine (PHI)-like immunoreactivity in the rat brain and spinal cord was investigated using the peroxidase-antiperoxidase technique. PHI-like immunoreactive neurons are principally localized in the cerebral cortex, hippocampus, suprachiasmatic and paraventricular nuclei of the hypothalamus, the central gray and raphe nuclei of the brain stem, as well as in the spinal nucleus and tract of the trigeminal nerve in the medulla oblongata. PHI-like immunoreactive terminals were densely distributed in the bed nucleus of the stria terminalis, central amygdaloid nucleus, interperduncular nucleus, spinal nucleus and tract of the trigeminal nerve, and dorsal horn of the spinal cord. The origin of PHI-like fibers in the spinal cord and their functional significance are discussed.