The ORL1 receptor (opioid receptor-like 1) and its endogenous ligand, nociceptin, are involved in nociperception. We have studied, in a deafferented animal model, the modification of medullar [(3)H]nociceptin binding site density. A rhizotomy was carried out in rats at the cervicothoracic level, and the dorsal afferent fibers from C5 to T1 were lesioned. Seven days after surgery, animals were sacrificed, and the binding of [(3)H]nociceptin (2 nM) was then performed on spinal cord sections. An autoradiographic analysis revealed a significant reduction (-18%) of [(3)H]nociceptin binding site density in the dorsal horn ipsilateral to the deafferentation compared with the contralateral side of the lesion. In the ventral horn, no significant difference (-5%) of binding was observed in the ipsilateral side of the deafferentation compared with the contralateral side. Thus, [(3)H]nociceptin binding sites appear to be located mainly on either interneurons or deutoneurons of the spinal cord, because the bulk of the labeling is spared by the lesion. However, the significant reduction of labeling that occurs on the dorsal part of the ipsilateral side to the lesion indicates that [(3)H]nociceptin binding sites are also present on these dorsal afferent fibers.
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http://dx.doi.org/10.1002/jnr.10218 | DOI Listing |
Neurobiol Dis
September 2009
Department of Pharmacobiology, Center of Research and Advanced Studies, Mexico City, Mexico.
There is no information concerning signal transduction mechanisms downstream of the opioid/nociceptin receptors in the human epileptic brain. The aim of this work was to evaluate the level of G-proteins activation mediated by DAMGO (a mu receptor selective peptide) and nociceptin, and the binding to mu and nociceptin (NOP) receptors and adenylyl cyclase (AC) in neocortex of patients with pharmacoresistant temporal lobe epilepsy. Patients with temporal lobe epilepsy associated with mesial sclerosis (MTLE) or secondary to tumor or vascular lesion showed enhanced [3H]DAMGO and [3H]forskolin binding, lower DAMGO-stimulated [35S]GTPgammaS binding and no significant changes in nociceptin-stimulated G-protein.
View Article and Find Full Text PDFSeizure
October 2007
Department of Pharmacobiology, Center for Research and Advanced Studies, Mexico.
Opioid receptor binding was evaluated in parahippocampal cortex (PHC) obtained from patients with intractable mesial temporal lobe epilepsy (MTLE) with and without subacute high frequency electrical stimulation (HFS) in this brain area. Mu, delta and nociceptin receptor binding was determined by autoradiography in PHC of five patients (ESAE group) with MTLE history of 14.8 +/- 2.
View Article and Find Full Text PDFBrain Res
September 2006
Unité de Neuropsychopharmacologie de la Dépression, Faculté de Médecine-Pharmacie, Rouen Cedex 1, France.
We studied the involvement of endogenous ORL1 (NOP) receptors in the anxiety state. In mice selected as "anxious" and "non-anxious", ORL1 (NOP) receptor has been analysed by means of two autoradiographic approaches: [3H]nociceptin binding and nociceptin-stimulated [35S]GTPgammaS binding. We show that differences in anxiety state are associated with differences in G protein coupling efficiency of ORL1 (NOP) receptor in the nucleus accumbens, without any change in the density of the receptors.
View Article and Find Full Text PDFJ Neurosci Res
August 2005
Unité de Neuropsychopharmacologie Expérimentale, CNRS FRE 2735, IFRMP No. 23, Faculté de Médecine-Pharmacie, Rouen, France.
Brain Res Bull
January 2005
Department of Pathology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.
The occurrence of systematic diurnal variations in pain thresholds has been demonstrated in human. Salivary melatonin levels change following acute pain when other factors that could explain the change have been removed or controlled. Melatonin-induced analgesia is blocked by naloxone or pinealectomy.
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