Biochemical anti-opioid action of NPFF2 receptors in rat spinal cord

Neuropeptide FF (NPFF) agonists counteract the cellular opioid actions. We demonstrate for the first time a biochemical anti-opioid effect of NPFF receptors in the rat spinal cord by using the [35S]GTPγS binding assay in autoradiography. The mu agonist DAMGO as well as the potent and selective NPFF2 agonist dNPA, stimulated [35S]GTPγS binding at different optimal GDP concentrations. dNPA decreased the effects induced by DAMGO alone; the maximal of G-protein coupling was decreased but not the potency of opioid agonist. We conclude that NPFF2 receptors are coupled to G-protein in the rat spinal cord and could exert a molecular anti-opioid effect.