title: Cholesterol-rich lipid rafts are involved in neuropeptide FF anti-nociceptin/orphanin FQ effect.
abstract: The participation of a signaling platform to the anti-nociceptin/orphanin FQ (N/OFQ) effect of neuropeptide FF (NPFF) receptors was investigated in both acutely dissociated neurons and SH-SY5Y human neuroblastoma cells. The NPFF anti-N/OFQ, not anti-μ opioid effect, on the Ca2+transient triggered by depolarization was reversed by methyl-β-cyclodextrin which depletes cholesterol from cell membranes. While the inactive α-cyclodextrin had no effect. By using [35S]GTPγS binding assay, a significant 20% decrease in the activity of nociceptin/orphanin FQ peptide receptors induced by the NPFF analog 1DMe was observed in detergent-resistant membranes, but not in total membranes of SH-SY5Y cells. Moreover, siRNA knock-down of G-protein-coupled receptor kinase 2 indicated that G-protein-coupled receptor kinase 2, but not protein kinase C, acted as the mediator in the NPFF anti-N/OFQ process. These data indicate that cholesterol-rich lipid rafts play an important role in the anti-N/OFQ effect of NPFF receptors. We proposed the participation of a signaling platform to the anti-Nociceptin/Orphanin FQ (N/OFQ) effect of Neuropeptide FF (NPFF) receptors both in mouse neurons and SH-SY5Y cells, with GRK2 protein acting as the mediator in this process. These findings should provide a more precise way to understand the anti-opioid effect of NPFF. NOP, Nociceptin/Orphanin FQ peptide.
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, CNRS / Université de Toulouse, Toulouse Cedex, France.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Ding
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, CNRS / Université de Toulouse, Toulouse Cedex, France.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Zajac
keywords: GRK2; anti-N/OFQ; membrane/lipid rafts; methyl-β-cyclodextrin; neuropeptide FF