Antinociceptive effects of H₃ (R-methylhistamine) and GABA(B) (baclofen)-receptor ligands in an orofacial model of pain in rats.
PMID 23463522 · Neurotoxicity research · 2013 · DOI 10.1007/s12640-013-9385-4
Authors: Przemysław Nowak; Magdalena Kowalińska-Kania; Damian Nowak; Richard M Kostrzewa; Jolanta Malinowska-Borowska
Abstract
The present study explored the antinociceptive effects of H₃ (R-methylhistamine) and GABA(B) (baclofen) receptor ligands in an orofacial model of pain in rats. Orofacial pain was induced by subcutaneous injection of formalin (50 μl, 5 %) in the upper lip region, and the number of jumps and time spent face rubbing was recorded for 40 min. Formalin produced a marked biphasic pain response; first phase, 0-10 min (jumps), and second phase, 15-40 min, (rubbing). Baclofen (50 μg) injected into the rat wiskerpad 5 min before formalin administration suppressed both phases of pain whereas R-alpha-methylhistamine (12.5 μg) abolished the first phase only. Brains were taken immediately after behavioral testing was completed. HPLC/ED analysis showed that 5-hydroxytryptamine (5-HT) turnover was increased in hippocampus, thalamus, and brain stem of all formalin groups, excepting the baclofen group in which the balance of 5-HT metabolism was restored to control values. These findings demonstrate that GABA(B) receptors represent peripheral targets for analgesia. Consequently, locally administered baclofen may be a useful approach in treating inflammatory trigeminal pain.
Animals; Baclofen; Disease Models, Animal; Facial Pain; Female; GABA-B Receptor Agonists; Histamine Agonists; Injections, Subcutaneous; Ligands; Male; Methylhistamines; Pain Measurement; Rats; Rats, Wistar
Cite
Przemysław Nowak; Magdalena Kowalińska-Kania; Damian Nowak; Richard M Kostrzewa; Jolanta Malinowska-Borowska. Antinociceptive effects of H₃ (R-methylhistamine) and GABA(B) (baclofen)-receptor ligands in an orofacial model of pain in rats. Neurotoxicity research (2013). PMID 23463522. DOI 10.1007/s12640-013-9385-4.