TY - JOUR
T1 - Antinociceptive Effects of H3 (R-methylhistamine) and GABA B (baclofen)-Receptor Ligands in an Orofacial Model of Pain in Rats
AU - Nowak, Przemysław
AU - Kowalińska-Kania, Magdalena
AU - Nowak, Damian
AU - Kostrzewa, Richard M.
AU - Malinowska-Borowska, Jolanta
PY - 2013/8/1
Y1 - 2013/8/1
N2 - The present study explored the antinociceptive effects of H3 (R-alpha-methylhistamine) and GABAB (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 GABAB receptors represent peripheral targets for analgesia. Consequently, locally administered baclofen may be a useful approach in treating inflammatory trigeminal pain.
AB - The present study explored the antinociceptive effects of H3 (R-alpha-methylhistamine) and GABAB (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 GABAB receptors represent peripheral targets for analgesia. Consequently, locally administered baclofen may be a useful approach in treating inflammatory trigeminal pain.
KW - GABA receptor B
KW - H receptor 3
KW - formalin test
KW - orofacial pain
KW - rats
UR - https://dc.etsu.edu/etsu-works/14224
UR - https://doi.org/10.1007/s12640-013-9385-4
U2 - 10.1007/s12640-013-9385-4
DO - 10.1007/s12640-013-9385-4
M3 - Article
VL - 24
JO - Neurotoxicity Research
JF - Neurotoxicity Research
ER -