Intra-paragigantocellularis lateralis injection of orexin-A has an antinociceptive effect on hot plate and formalin tests in rat.
In the present study, the effect of orexin-A (ORXA) microinjection into the paragigantocellularis lateralis (LPGI) on nociceptive behaviors, using hot-plate and formalin tests as thermal and chemical models of pain in rat, was examined. Also, we determined whether the pretreatment with SB-334867, a selective OX1-receptor antagonist, would prevent the antinociceptive effect of orexin-A. ORXA (0.1-100 nM/0.5 μL) microinjected into the LPGi nucleus, dose-dependently decreased the formalin induced nociceptive behaviors and also produced a dose-dependent antinociceptive effect in the hot-plate test. Pretreatment with a selective orexin receptor 1 (OX1R) antagonist, SB-334867, also inhibited the effect of ORXA on formalin induced nociceptive behaviors while the SB-334867 (100 μM) alone had no effect on formalin test. These data demonstrated that the ORXA-induced antinociception in formalin test is mainly mediated through the OX1R in LPGi which might play a potential role in processing the pain information associated with descending pain modulation.
Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
Elaheh
E
Erami
Hassan
H
Azhdari-Zarmehri
Elmira
E
Ghasemi-Dashkhasan
Mohammad-Hossein
MH
Esmaeili
Saeed
S
Semnanian
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D007276:Injections, Intraventricular; D047908:Intracellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000378:metabolism*; D008845:Microinjections; D009479:Neuropeptides / Q000008:administration & dosage / Q000378:metabolism*; D059225:Nociception / Q000502:physiology*; D064446:Orexin Receptors; D000068797:Orexins; D010147:Pain Measurement; D017288:Pain Threshold; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000378:metabolism*
C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide