title: Vitamin B complex attenuated heat hyperalgesia following infraorbital nerve constriction in rats and reduced capsaicin in vivo and in vitro effects.
abstract: Vitamins of the B complex attenuate some neuropathic pain sensory aspects in various animal models and in patients, but the mechanisms underlying their effects remain to be elucidated. Herein it was investigated if the treatment with a vitamin B complex (VBC) reduces heat hyperalgesia in rats submitted to infraorbital nerve constriction and the possibility that TRPV1 receptors represent a target for B vitamins. In the present study, the VBC refers to a combination of vitamins B1, B6 and B12 at low- (18, 18 and 1.8mg/kg, respectively) or high- (180, 180 and 18mg/kg, respectively) doses. Acute treatment of rats with either the low- or the high-doses combination reduced heat hyperalgesia after nerve injury, but the high-doses combination resulted in a long-lasting effect. Repeated treatment with the low-dose combination reduced heat hyperalgesia on day four after nerve injury and showed a synergist effect with a single injection of carbamazepine (3 or 10mg/kg), which per se failed to modify the heat threshold. In naïve rats, acute treatment with the high-dose of VBC or B1 and B12 vitamins independently reduced heat hyperalgesia evoked by capsaicin (3µg into the upper lip). Moreover, the VBC, as well as, each one of the B vitamins independently reduced the capsaicin-induced calcium responses in HEK 293 cells transiently transfected with the human TRPV1 channels. Altogether, these results indicate that B vitamins can be useful to control heat hyperalgesia associated with trigeminal neuropathic pain and that modulation of TRPV1 receptors may contribute to their anti-hyperalgesic effects.
authors.affiliation: Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Kopruszinski
authors.affiliation: Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil.
authors.forename: Renata C
authors.initials: RC
authors.lastname: Reis
authors.affiliation: Institute of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen D-91054, Germany.
authors.forename: Elisangela
authors.initials: E
authors.lastname: Bressan
authors.affiliation: Institute of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen D-91054, Germany.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Reeh
authors.affiliation: Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil. Electronic address: juliana.chichorro@ufpr.br.
authors.forename: Juliana G
authors.initials: JG
authors.lastname: Chichorro
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology*; D002220:Carbamazepine / Q000494:pharmacology; D003250:Constriction; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D057809:HEK293 Cells; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy* / Q000209:etiology; D008297:Male; D009915:Orbit / Q000294:innervation*; D051381:Rats; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism; D014803:Vitamin B Complex / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D014803:Vitamin B Complex; D002220:Carbamazepine; D002211:Capsaicin; D002118:Calcium
keywords: Calcium imaging; Heat hyperalgesia; Infraorbital nerve constriction; Orofacial pain; TRPV1; Vitamin B complex