A novel member of the opioid related receptor family, the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor was identified and demonstrated to be involved in many physiological functions including pain regulation. [Nphe1]N/OFQ-(1-13)-NH2 (Nphe) is a novel peptide antagonist of NOP receptors, developed using peripheral preparations. We have quantitatively investigated the interaction of Nphe with N/OFQ, the endogenous ligand of NOP receptors, in the midbrain ventrolateral periaqueductal gray (PAG), a crucial brain region for N/OFQ-induced reversal of opioid analgesia, using the patch-clamp recording technique in brain slices. N/OFQ concentrationdependently activated an inwardly rectifying K+ current in response to hyperpolarization ramps from 60 to 140 mV. Nphe concentration- dependently attenuated the K+ current activated by N/OFQ without changing its reversal potential. The presence of Nphe rightshifted the concentration-response curve to N/OFQ in a parallel manner. The Schild plot analysis yielded a slope of 1.16 and a pA2 value of 6.64 that is similar to those obtained in peripheral preparations. At concentrations up to 3 μM, Nphe affected neither the membrane current per se, nor the inwardly rectifying K+ current activated by [D-Ala2, N-Me-Phe4,Gly-ol5]-enkephalin or baclofen, a mu-opioid and GABAB receptor agonist, respectively. It is concluded that Nphe acts as a pure, selective and competitive antagonist at native NOP receptors of ventrolateral PAG neurons.
[Nphe(1)]N/OFQ-(1-13)-NH2 is a competitive and selective antagonist at nociceptin/orphanin FQ receptors mediating K+ channel activation in rat periaqueductal gray slices
GUERRINI, Remo;CALO', Girolamo
2002
Abstract
A novel member of the opioid related receptor family, the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor was identified and demonstrated to be involved in many physiological functions including pain regulation. [Nphe1]N/OFQ-(1-13)-NH2 (Nphe) is a novel peptide antagonist of NOP receptors, developed using peripheral preparations. We have quantitatively investigated the interaction of Nphe with N/OFQ, the endogenous ligand of NOP receptors, in the midbrain ventrolateral periaqueductal gray (PAG), a crucial brain region for N/OFQ-induced reversal of opioid analgesia, using the patch-clamp recording technique in brain slices. N/OFQ concentrationdependently activated an inwardly rectifying K+ current in response to hyperpolarization ramps from 60 to 140 mV. Nphe concentration- dependently attenuated the K+ current activated by N/OFQ without changing its reversal potential. The presence of Nphe rightshifted the concentration-response curve to N/OFQ in a parallel manner. The Schild plot analysis yielded a slope of 1.16 and a pA2 value of 6.64 that is similar to those obtained in peripheral preparations. At concentrations up to 3 μM, Nphe affected neither the membrane current per se, nor the inwardly rectifying K+ current activated by [D-Ala2, N-Me-Phe4,Gly-ol5]-enkephalin or baclofen, a mu-opioid and GABAB receptor agonist, respectively. It is concluded that Nphe acts as a pure, selective and competitive antagonist at native NOP receptors of ventrolateral PAG neurons.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
