Immunohistochemical localization of ORL‐1 in the central nervous system of the rat

Abstract

A novel member of the opioid receptor family (ORL-1) has been cloned from a variety of vertebrates. ORL-1 does not bind any of the classical opioids, although a high affinity endogenous agonist with close homology to dynorphin has recently been identified. We have generated a monoclonal antibody to the N-terminus of ORL-1 to map areas of receptor expression in rat central nervous system (CNS). Intense and specific immunolabeling was observed in multiple areas in the diencephalon, mesencephalon, pons/medulla, and spinal cord. In the telencephalon, intense labeling was observed in the neuropil throughout layers II-V in the neocortex, the anterior olfactory nuclear complex, the pyriform cortex, the CA1-CA4 fields and dentate gyrus of the hippocampus, and in many of the septal and basal forebrain areas. In contrast to other members of the opioid receptor family, light labeling for ORL-1 was observed in telencephalic areas such as caudate-putamen. In the cerebellum, ORL-1 immunoreactivity was only observed in the deep nuclei. Throughout the CNS the majority of labelling was localized to fiber processes and fine puncta, although labeled scattered perikarya were observed in a few brain areas such as the hilus dentate in the hippocampus and some nuclei in the brainstem and spinal cord. The present mapping study is consistent with the reported distribution of ORL-1 mRNA and provides the first immunohistochemical report on anatomical and cellular distribution of ORL-1 receptor in the rat CNS.

A Role for Brain Stress Systems in Addiction

“…Neuronal perikarya are shown as solid circles, and fibers-terminals as short curved lines and dots. Data from Neal et al (1999); very similar results were reported by Anton et al (1996). AA, anterior amygdala; ABL, basolateral nucleus of amygdala; AC, anterior commissure; ACB, nucleus accumbens; ACE, central nucleus of the amygdala; ACO, cortical nucleus of amygdala; AD, anterodorsal nucleus of thalamus; AL, anterior lobe of pituitary; AM, anteromedial nucleus of thalamus; AMB, nucleus ambiguus; AME, medial nucleus of the amygdala; AON, anterior olfactory nucleus; ARC, arcuate nucleus; AV, anteroventral nucleus of thalamus; BST, bed nucleus of the stria terminalis; CC, corpus callosum; CGX, cingulate cortex; CM, central-medial nucleus of thalamus; COCH, cochlear nuclear complex; CPU, caudate-putamen; CST, corticospinal tract; DH, dorsal horn of spinal cord; DG, dentate gyrus; DM, dorsomedial nucleus of hypothalamus; DNV, dorsal motor nucleus of vagus; DTN, dorsal tegmental nucleus; ENT, entorhinal cortex; FN, fastigial nucleus of cerebellum; FRX, frontal cortex; GL, glomerular layer of olfactory bulb; GP, globus pallidus; HM, medial habenular nucleus; HPC, hippocampus; IC, inferior colliculus; IL, intermediate lobe of pituitary; IP, interpeduncular nuclear complex; LC, nucleus locus coeruleus; LG, lateral geniculate nucleus; LHA, lateral hypothalamic area; LRN, lateral reticular nucleus; MF, mossy fibers of hippocampus; MFN, motor facial nucleus; MG, medial geniculate nucleus; ML, medial lemniscus; MM, medial mammillary nucleus; MNT, mesencephalic nucleus of trigeminal; MVN, medial vestibular nucleus; NCU, nucleus cuneatus; NCX, neocortex; NDB, nucleus of diagonal band; NL, neural lobe of pituitary; NRGC, nucleus reticularis gigantocellularis; NRPG, nucleus reticularis paragigantocellularis; NTS, nucleus tractus solitarius; OCX, occipital cortex; OT, optic tract; OTU, olfactory tubercle; PAG, periaqueductal gray; PAX, periamygdaloid cortex; PBN, parabrachial nucleus; PC, posterior commissure; PIR, piriform cortex; PN, pons; POA, preoptic area; PP, perforant path; PV, periventricular nucleus of thalamus; PVN(M), paraventricular nucleus (pars magnocellularis); PVN(P), paraventricular nucleus (pars parvocellularis); RD, nucleus raphe dorsalis; RE, nucleus reuniens of thalamus; RF, reticular formation; RM, nucleus raphe magnus; RME, nucleus raphe medianus; SC, superior colliculus; SCP, superior cerebellar peduncle; SM, stria medullaris thalami; SNC, substantia nigra (pars compacta); SNR, substantia nigra (pars reticulata); SNT, sensory nucleus of trigeminal (main); SON, supraoptic nucleus; SPT, septal nuclei; STN, spinal nucleus of trigeminal; SUB, subiculum; VM, ventromedial nucleus of hypothalamus; VP, ventral pallidum; ZI, zona incerta.…”

Direct inhibition of hypocretin/orexin neurons in the lateral hypothalamus by nociceptin/orphanin FQ blocks stress-induced analgesia in rats

“…Although Hcrt neurons do not constitute a nucleus, they are exclusively located in the lateral hypothalamus. In contrast, N/OFQ-containing neurons and fibers are widely distributed throughout the brain of rodents (Neal, Jr. et al, 1999;Anton et al, 1996). We observed N/OFQ-immunoreactive cells in the lateral hypothalamic area and in the area dorsal to the core of distribution of Hcrt-immunoreactive cells.…”

Mu and kappa opioid receptor expression in the mediobasal hypothalamus and effectiveness of selective antagonists on prolactin release during lactation

“…This effect of OFQ is mediated via actions at ORL-1 receptor subtype and OFQ contributes to suckling-induced prolactin release (Chesterfield et al, 2006). Since moderate to dense OFQ binding, receptor mRNA expression (Neal et al, 1999) and immunoreactivity (Anton et al, 1996) is found in arcuate nucleus, further research is required to determine if ORL-1 expression is changed during lactation.…”