Biomedical subjects

S Gicquel

Publications and source records attributed to S Gicquel.

5 recordsLinked to original sources

PubMed1998

Antisense oligonucleotides to human SQA-neuropeptide FF decrease morphine tolerance and dependence in mice.

Neuropeptide FF (Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) is able to modulate opioid analgesia. Intracerebroventricular treatment for 5 days with antisense-oligodeoxynucleotides complementary to the sequence of human SQA-neuropeptide FF (Ser-Gln-Ala-Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) precursor gene or by mismatch-oligodeoxynucleotides did not change the antinociceptive activity of morphine in the mouse tail flick test. In contrast, antisense- but not mismatch-oligodeoxynucleotides attenuated significantly the tolerance to the analgesic activity of morphine and the withdrawal syndrome precipitated by naloxone in morphine-treated mice. These treatments with oligodeoxynucleotides did not modify neuropeptide FF-immunoreactivity content in whole brain but repeated injections of an agonist of neuropeptide FF receptors increased the intensity of morphine tolerance. These results demonstrate the important role of neuropeptide FF in opioid pharmacodependence.

Amino Acid Sequence↗

PubMed1994

Structure-activity study of neuropeptide FF: contribution of N-terminal regions to affinity and activity.

Twenty neuropeptide FF (NPFF) analogs having various lengths were synthesized by solid-phase peptide synthesis to gain more information on the role of N-terminal residues for the NPFF receptor affinity. The affinities were evaluated in the rat spinal cord membrane preparations, and the biological activities were measured on morphine analgesia in the mouse tail-flick test. Shortening of the NPFF sequence from the N-terminal produced only a moderate decrease in affinity until NPFF (4-8) was reached. In the same way, NPFF(3-8) significantly decreased morphine analgesia, while NPFF(4-8) had no significant effect at a dose of 22 nmol. The introduction in the N-terminal part of NPFF of a D-enantiomer at positions 2 and 1 or the presence of an N-methyl group on position 3 did not modify affinity and activity. Substitution of proline5 by the D-isomer decreased the affinity of NPFF analogs whatever their length, and [Tyr1,D-Pro5]NPFF(1-8) was 2.5-fold less potent than [Tyr1]NPFF(1-8) in reversing morphine-induced analgesia. In contrast, the presence of a glycine residue in position 5 did not influence the affinity toward NPFF receptors. Data provide evidence that the N-terminal segment of neuropeptide FF is responsible for high-affinity binding.

Amino Acid Sequence↗

PubMed1993

Comparative action of Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 analogs on intestinal motility and nociception in rats.

Central (i.c.v.) effects of D-Tyr-D-Leu-[N-Me]-Phe-Gln-Pro-Gln-Arg-Phe-NH2 [(1DME)Y8Fa] and D-Tyr-D-Leu-D-Phe-Gln-Pro-Gln-Arg-Phe-NH2 [(3D)Y8Fa], synthetic analogs of Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 on intestinal myoelectric activity and nociception were studied and compared to that of D-Ala2-Met5-enkephalinamide in rats. The duration of disruption of intestinal migrating myoelectric complexes, induced by p.o. administration of a test meal was significantly shortened (P < .01) by (1DME)Y8Fa and (3D)Y8Fa (8, 40 and 80 micrograms/kg) and D-Ala2-Met5-enkephalinamide (40 and 80 micrograms/kg). The coadministration of any two of these drugs, at doses of nonmeasurable effect when given alone (2 micrograms/kg), has also reduced the duration (P < .01) of the postprandial intestinal motor profile. Both separate and combined effects of drugs were antagonized by naloxone (1 mg/kg s.c.). In contrast, in the tail-flick test, analgesia induced by D-Ala2-Met5-enkephalinamide (40 micrograms/kg i.c.v.) was blocked by (1DME)Y8Fa, (3D)Y8Fa (8 micrograms/kg) and naloxone (1 mg/kg s.c.). The coadministration of (1DME)Y8Fa and (3D)Y8Fa at doses of no proper effect when given alone (8 micrograms/kg) has significantly (P < .01) reduced the latency time. This effect was not blocked by naloxone (1 mg/kg s.c.). It is concluded that the Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 analogs, (1DME)Y8Fa and (3D)Y8Fa, when given i.c.v. exert effects similar to opiate agonists and antagonists on intestinal myoelectrical activity and on nociception, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1992

Analogues of F8Famide resistant to degradation, with high affinity and in vivo effects.

Four analogues of Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2, a mammalian FMRFamide-like peptide with antiopiate properties, were synthesized with N-terminus modifications and were shown to have high affinity for F8Famide binding sites. The degradation rate of these analogues in mouse brain slices was 3 times lower than that of the natural peptide. One analogue, (2DME)Y8Fa (D.Tyr-D.Leu-[N-Me]Phe-Gln-Pro-Gln-Arg-Phe-NH2), produced a clear hyperalgic effect and inhibited morphine analgesia in the mouse tail-flick test at lower doses than did the parent compound. (3D)Y8Fa (D.Tyr-D.Leu-D.Phe-Gln-Pro-Gln-Arg-Phe-NH2) and (2D)Y8Fa (D.Tyr-D.Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) in contrast did not decrease morphine analgesia but were analgesic alone. The analgesic effects of 22 nmol (2D)Y8Fa and (3D)Y8Fa were decreased by (1DME)Y8Fa (D.Tyr-Leu-[N-Me]Phe-Gln-Pro-Gln-Arg-Phe-NH2) or (2DME)Y8Fa and were reversed by naloxone. These results indicate opioid modulating properties of F8Famide. These analogues may prove to be useful tools for studying the modulation of pain by F8Famide.

Amino Acid Sequence↗

PubMedDate not supplied

Effects of F8Famide analogs on intestinal transit in mice.

In an attempt to establish the role of F8Famide in opioid activity modulation, we examined the effects of intracerebroventricular administration of the F8Famide analogs (1DME)Y8Fa and (3D)Y8Fa on intestinal transit in mice. (1DME)Y8Fa (0.88 to 22 nmol) inhibited intestinal transit as did F8Famide and morphine. An IP injection of naloxone (2 mg/kg) decreased the morphine effect but had no effect on the response to (1DME)Y8Fa. In contrast, a subthreshold dose of morphine (0.22 nmol) inhibited the response to (1DME)Y8Fa, (3D)Y8Fa delayed intestinal transit only at large dose (22 nmol) but decreased (1DME)Y8Fa and morphine effects at lower ineffective doses. Our findings demonstrate that although F8Famide and morphine could induce the same pharmacological effect, F8Famide receptor activity was modulated by a low-level stimulation of opioid receptors. Furthermore, (3D)Y8Fa should be a useful probe to elucidate neuronal mechanisms controlled by opioids.

Amino Acid Sequence↗