title: B vitamins relieve neuropathic pain behaviors induced by infraorbital nerve constriction in rats.
abstract: OBJECTIVE
  There is mounting evidence that use of B vitamins can help control neuropathic pain. This study investigated if treatment with B1, B6 and B12 vitamins, alone or in combination with carbamazepine, can ameliorate distinct nociceptive behaviors in a model of trigeminal neuropathic pain.
  
  
  METHODS
  Male Wistar rats were submitted to infraorbital nerve constriction or sham surgery and received a 5-day treatment with one of the B vitamins, a single carbamazepine injection or the association of both treatments and were tested for facial thermal and mechanical hyperalgesia at different time intervals.
  
  
  RESULTS
  Repeated treatment with B1 (thiamine), B6 (pyridoxine) and B12 (cyanocobalamin) vitamins (at 180, 180 and 18 mg/kg/day, respectively, for 5 days) prevented the development of heat hyperalgesia after infraorbital nerve injury, but only B12 and B6 treatments attenuated cold and mechanical hyperalgesia, respectively. A single injection of carbamazepine (30 mg/kg) significantly reduced thermal, but not mechanical, hyperalgesia after nerve injury. Combinations of lower doses of each B vitamin (B1 and B6 at 18 mg/kg/day and B12 at 1.8 mg/kg/day for 5 days) with carbamazepine (10mg/kg) markedly reduced heat hyperalgesia after infraorbital nerve injury. Treatment with B12 (1.8 mg/kg/day) combined with carbamazepine (10mg/kg) also synergized to attenuate cold hyperalgesia at some time points, but combination of B6 (18 mg/kg/day) with carbamazepine (30 mg/kg) failed to modify mechanical hyperalgesia.
  
  
  CONCLUSIONS
  We suggest that B vitamins might constitute a relevant adjuvant to control some aspects of the pain afflicting patients suffering from trigeminal neuropathic pain.
authors.affiliation: Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Kopruszinski
authors.forename: Renata C
authors.initials: RC
authors.lastname: Reis
authors.forename: Juliana G
authors.initials: JG
authors.lastname: Chichorro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002220:Carbamazepine / Q000494:pharmacology; D006930:Hyperalgesia / Q000517:prevention & control; D008297:Male; D009408:Nerve Compression Syndromes / Q000150:complications*; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology*; D009915:Orbit / Q000294:innervation*; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D014803:Vitamin B Complex / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D014803:Vitamin B Complex; D002220:Carbamazepine