title: Rat ventral midbrain dopamine neurons express the orphanin FQ/nociceptin receptor ORL-1.
abstract: Orphanin FQ/nociceptin, (OFQ/N) the endogenous ligand for the ORL-1 receptor, has been shown previously to modulate extracellular dopamine concentration in the nucleus accumbens following both intracerebroventricular and intra-ventral tegmental area administration. However, it is unclear whether or not this is a result of a direct action of OFQ/N on ORL-1 receptors located on dopamine neurons. We sought evidence for expression of the ORL-1 receptor in dopamine cells located in the ventral tegmental area and substantia nigra of the rat brain using double-label in situ hybridization. Within the ventral tegmental area, 91% of tyrosine hydroxylase-positive cells were also positive for ORL-1 hybridization. Similarly, in the substantia nigra 90% of tyrosine hydroxylase-positive cells in the zona compacta expressed ORL-1 message and 84% of tyrosine hydroxylase-positive cells in the zona reticulata colocalized ORL-1 message. These data provide the anatomical basis for a direct modulatory effect of OFQ/N on mid-brain dopamine neurons.
authors.affiliation: Department of Psychiatry, UC Irvine College of Medicine, 356 Medical Surgery II, CA 92697-4625, USA.
authors.forename: Nigel T
authors.initials: NT
authors.lastname: Maidment
authors.forename: Yiling
authors.initials: Y
authors.lastname: Chen
authors.forename: Aiko M
authors.initials: AM
authors.lastname: Tan
authors.forename: Niall P
authors.initials: NP
authors.lastname: Murphy
authors.forename: Frances M
authors.initials: FM
authors.lastname: Leslie
mesh_terms: D000818:Animals; D002452:Cell Count; D004298:Dopamine / Q000378:metabolism*; D017403:In Situ Hybridization; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009714:Nucleus Accumbens / Q000166:cytology / Q000378:metabolism; D015345:Oligonucleotide Probes; D018847:Opioid Peptides / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000235:genetics*; D013378:Substantia Nigra / Q000166:cytology / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics; D017557:Ventral Tegmental Area / Q000166:cytology / Q000378:metabolism*; D000094942:Nociceptin Receptor; D000097629:Nociceptin
chemical_list: D004298:Dopamine; D015345:Oligonucleotide Probes; D018847:Opioid Peptides; D012333:RNA, Messenger; D011957:Receptors, Opioid; D014446:Tyrosine 3-Monooxygenase; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C000722285:Oprl1 protein, rat