Nociceptive and inflammatory responses induced by formalin in the orofacial region of rats: effect of anti-TNFalpha strategies

Int Immunopharmacol. 2009 Jan;9(1):80-5. doi: 10.1016/j.intimp.2008.10.001. Epub 2008 Oct 26.

Abstract

This study evaluated the effects of different anti-TNFalpha strategies on the nociceptive and inflammatory responses triggered by formalin in the rat orofacial region. Formalin injection (2.5%) into the right upper lip caused a nociceptive response that was biphasic, with the first phase observed between 0 and 3 min and the second phase between 12 and 30 min. Plasma extravasation induced by formalin was time-related and reached the peak at 360 min. The monoclonal antibody anti-TNFalpha (25 and 50 pg/lip) significantly inhibited the second phase of formalin-induced nociceptive behavior, while the first phase remained unaltered. The systemic treatment with the chimeric anti-TNFalpha antibody infliximab also caused a significant inhibition of the second phase. Interestingly, the local administration of infliximab (50 pg/lip) produced a significant reduction of both phases of formalin-induced nociception. In addition, the systemic pretreatment with the preferential inhibitor of TNFalpha synthesis thalidomide (25 and 50 mg/kg, p.o) promoted a marked reduction of the first and second phases of formalin-evoked nociception. The local administration of the monoclonal antibody anti-TNFalpha (25 and 50 pg/lip) or infliximab (50 pg/lip) markedly reduced the plasma extravasation induced by formalin. Otherwise, formalin-elicited plasma extravasation was not significantly affected by the systemic administration of either infliximab (1 mg/kg; s.c) or thalidomide (50 mg/kg, p.o). Present data suggest that blocking TNFalpha effects, through different pharmacological tools, could represent a good alternative to control orofacial inflammatory pain that is refractory to other drugs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / therapeutic use
  • Antibodies, Monoclonal / therapeutic use
  • Behavior, Animal / drug effects
  • Capillary Permeability / drug effects
  • Facial Pain / chemically induced*
  • Facial Pain / pathology*
  • Facial Pain / psychology
  • Formaldehyde / administration & dosage
  • Formaldehyde / pharmacokinetics
  • Formaldehyde / toxicity*
  • Immunosuppressive Agents / therapeutic use
  • Inflammation / chemically induced*
  • Inflammation / pathology
  • Infliximab
  • Injections
  • Lip
  • Male
  • Pain Measurement / drug effects
  • Rats
  • Rats, Wistar
  • Thalidomide / therapeutic use
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Antibodies, Monoclonal
  • Immunosuppressive Agents
  • Tumor Necrosis Factor-alpha
  • Formaldehyde
  • Thalidomide
  • Infliximab