Anti-allodynic effect of intracerebroventricularly administered antioxidant and free radical scavenger in a mouse model of orofacial pain.
OBJECTIVE
To evaluate possible effects of the intracerebroventricular (icv) injection of either O-Tricyclo [5.2.1.0(2,6)] dec-9-yl dithiocarbonate potassium salt (D609), a potent antioxidant and inhibitor of phosphatidylcholine specific phospholipase C (PtdCho-PLC) and acid sphingomyelinase (ASMase), or the spin trap/free radical scavenger N-tert-Butyl-alpha-phenylnitrone (PBN), on mechanical allodynia induced by facial carrageenan injection in mice.


METHODS
Balb/c mice received icy injection of D609/PBN plus facial carrageenan injection, and the number of face wash strokes to von Frey hair mechanical stimulation of the maxillary skin was quantified. PtdCho-PLC and ASMase activities were also assayed in the brainstem, thalamus, and somatosensory cortex.


RESULTS
Mice that received the icy injection of 10 nmol D609 plus facial carrageenan injection showed significantly fewer face wash strokes evoked by von Frey hair stimulation (indicating reduced mechanical allodynia) at 1 and 3 days post-injection, compared to mice that received icy injection of isotonic saline plus facial carrageenan injection. Mice that received icy injection of 1.13 micromol PBN plus facial carrageenan injection likewise showed significantly fewer face wash strokes after facial carrageenan injection, compared to isotonic saline-injected plus carrageenan-injected controls. D609 injection also resulted in significantly reduced ASMase activity in the brainstem, thalamus, and somatosensory cortex 3 days after injection, compared to controls.


CONCLUSIONS
The icv injections of D609 and PBN were effective in reducing mechanical allodynia after facial carrageenan injection-induced pain. Together, the results point to a possible role of central nervous system sphingolipids and/or free radicals in orofacial pain.
Tang
Ning
N
Department of Oral and Maxillofacial Surgery, National University of Singapore.
Ong
Wei-Yi
WY
Yeo
Jin-Fei
JF
Farooqui
Akhlaq A
AA
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D001933:Brain Stem / Q000187:drug effects / Q000201:enzymology; D001952:Bridged-Ring Compounds / Q000008:administration & dosage / Q000627:therapeutic use; D002351:Carrageenan / Q000009:adverse effects; D002552:Cerebral Ventricles / Q000187:drug effects / Q000201:enzymology; D003497:Cyclic N-Oxides / Q000008:administration & dosage / Q000627:therapeutic use; D004195:Disease Models, Animal; D005157:Facial Pain / Q000139:chemically induced / Q000188:drug therapy*; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000627:therapeutic use*; D007276:Injections, Intraventricular; D008297:Male; D008442:Maxillary Nerve / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D009636:Norbornanes; D013003:Somatosensory Cortex / Q000187:drug effects / Q000201:enzymology; D013107:Sphingolipids / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors; D013268:Stimulation, Chemical; D013788:Thalamus / Q000187:drug effects / Q000201:enzymology; D013859:Thiocarbamates; D013871:Thiones / Q000008:administration & dosage / Q000627:therapeutic use; D012668:Trigeminal Ganglion / Q000187:drug effects*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D000975:Antioxidants; D001952:Bridged-Ring Compounds; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D009636:Norbornanes; D013107:Sphingolipids; D013859:Thiocarbamates; D013871:Thiones; C029217:phenyl-N-tert-butylnitrone; C046498:tricyclodecane-9-yl-xanthogenate; D002351:Carrageenan; D010738:Type C Phospholipases; D013108:Sphingomyelin Phosphodiesterase