Neuropeptide FF receptor modulates potassium currents in a dorsal root ganglion cell line.

This study investigated the presence of neuropeptide FF (NPFF) receptors on F-11 cells, a hybridoma derived from rat dorsal root ganglia (DRG) and mouse neuroblastoma. Binding experiments revealed a low density (4 fmol/mg) of high affinity (0.5 nM) [(3)H]-EYF binding sites in these cells.

Staurosporine differentiation of NPFF2 receptor-transfected SH-SY5Y neuroblastoma cells induces selectivity of NPFF activity towards opioid receptors.

Activation of the NPFF(2) receptor reduces the inhibitory effect of opioids on the N-type Ca(2+) channel. Although this anti-opioid effect is specific for opioid receptors in neurons and tissues, it also affects NPY Y2 and alpha(2)-adrenoreceptors in undifferentiated SH-SY5Y cells stably expressing the NPFF(2) receptor. To test whether this difference could be due to the immaturity of these cells, they were differentiated to a noradrenergic neuronal phenotype with staurosporine.

Physical association between neuropeptide FF and micro-opioid receptors as a possible molecular basis for anti-opioid activity.

Neuropeptide FF (NPFF) modulates the opioid system by exerting functional anti-opioid activity on neurons, the mechanism of which is unknown. By using a model of SH-SY5Y cells, we recently postulated that anti-opioid activity likely takes place upstream from the signaling cascade, suggesting that NPFF receptors could block opioid receptors by physical interaction. In the present study, fluorescence techniques were used to monitor the physical association and the dynamic of NPFF2 and micro-opioid (MOP) receptors tagged with variants of the green fluorescent protein.

Anti-opioid activities of NPFF1 receptors in a SH-SY5Y model.

In order to elucidate the mechanisms of the neuronal anti-opioid activity of Neuropeptide FF, we have transfected the SH-SY5Y neuroblastoma cell line, which expresses mu- and delta-opioid receptors, with the human NPFF1 receptor. The SH1-C7 clone expresses high affinity NPFF1 receptors in the same range order of density as opioid receptors. Similarly to the opioids, acute stimulation with the NPFF1 agonist NPVF inhibits adenylyl cyclase activity and voltage-gated (N-type) Ca2+ currents and enhances the intracellular Ca2+ release triggered by muscarinic receptors activation.

Anti-analgesia of a selective NPFF2 agonist depends on opioid activity.

NPFF agonists designed to be selective NPFF(2) receptor probes were synthesized. D.Asn-Pro-(N-Me)Ala-Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH(2) (dNPA) displays a very high affinity (0.

Opioid-modulating peptides: mechanisms of action.

Opioids are involved in the physiological control of numerous functions of the central nervous system, particularly nociception. It appears that some endogenous neuropeptides, called anti-opioids, participate in an homeostatic system tending to reduce the effects of opioids. Neuropeptide FF (NPFF) and cholecystokinin (CCK) possess these properties and, paradoxically, the opioid peptides nociceptin and dynorphin display some anti-opioid activity.

Neuropeptide FF (NPFF) analogs functionally antagonize opioid activities in NPFF2 receptor-transfected SH-SY5Y neuroblastoma cells.

To elucidate the mechanism of the cellular antiopioid activity of neuropeptide FF (NPFF), we have transfected the SH-SY5Y neuroblastoma cell line, which expresses mu-and delta-opioid receptors, with the human NPFF2receptor. The selected clone, SH2-D9, expressed high-affinity NPFF2 receptors in the same range order as mu- and delta-opioid receptors (100-300 fmol/mg of protein). The NPFF analog [D-Tyr1, (NMe)Phe3]NPFF (1DMe) did not modify the binding parameters of the mu- and delta-specific agonists [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin and deltorphin-I, respectively.

Neuropeptide FF receptors 1 and 2 exert an anti-opioid activity in acutely dissociated rat dorsal raphe and periventricular hypothalamic neurones.

We measured the reduction by nociceptin of the [Ca(2+)](i) transient triggered by depolarization in acutely dissociated neurones of the rat dorsal raphe and periventricular hypothalamic nuclei that express NPFF(2) and NPFF(1) receptors, respectively, in the absence and presence of 10 nM of NPA-NPFF or NPVF, two peptides selective for NPFF(2) and NPFF(1) receptors, respectively. In dorsal raphe neurones, NPA-NPFF reduces the inhibition of Ca(2+) conductances by nociceptin while NPVF is inactive. In periventricular hypothalamic neurones, both peptides reduce the inhibition of Ca(2+) transients by nociceptin, NPVF having a significantly larger effect than NPA-NPFF.