Antinociceptive effects of citronellal in formalin-, capsaicin-, and glutamate-induced orofacial nociception in rodents and its action on nerve excitability.
OBJECTIVE
To evaluate the antinociceptive effects of citronellal (CTL) on formalin-, capsaicin-, and glutamate-induced orofacial nociception in mice and to investigate whether such effects might involve a change in neural excitability.


METHODS
Male mice were pretreated with CTL (50, 100, and 200 mg/kg, ip), morphine (5 mg/kg, ip), or vehicle (distilled water plus one drop of Tween 80 0.2%) before formalin (20 microL, 2%), capsaicin (20 microL, 2.5 microg) or glutamate (40 microL, 25 microM) injection into the right vibrissa. Sciatic nerve recordings were made using the single sucrose gap technique in rats. The data obtained were analyzed by ANOVA followed by Dunnett's test for the behavioral analyses and by the Student t test for CAP evaluation.


RESULTS
Pretreatment with CTL was effective in reducing nociceptive face-rubbing behavior in both phases of the formalin test, which was also naloxone-sensitive. CTL produced significantly antinociceptive effect at all doses in the capsaicin- and glutamate- tests. Rota-rod testing indicated that such results were unlikely to be provoked by motor abnormality. Recordings using the single sucrose gap technique revealed that CTL (10 mM) could reduce the excitability of the isolated sciatic nerve through a diminution of the compound action potential amplitude by about 42.4% from control recordings.


CONCLUSIONS
These results suggest that CTL might represent an important tool for management and/or treatment of orofacial pain.
Quintans-Júnior
Lucindo José
LJ
Departamento de Fisiologia, Universidade Federal de Sergipe, Campus Universitário, Laboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, Brazil. lucindo_jr@yahoo.com.br
Melo
Mônica S
MS
De Sousa
Damião P
DP
Araujo
Adriano Antunes Souza
AA
Onofre
Alexandre C S
AC
Gelain
Daniel P
DP
Gonçalves
Juan C R
JC
Araújo
Demétrius A M
DA
Almeida
Jackson R G S
JR
Bonjardim
Leonardo R
LR
D000200:Action Potentials / Q000187:drug effects; D000080462:Acyclic Monoterpenes; D000447:Aldehydes / Q000627:therapeutic use*; D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D002211:Capsaicin / Q000009:adverse effects*; D005157:Facial Pain / Q000139:chemically induced / Q000188:drug therapy*; D005557:Formaldehyde / Q000009:adverse effects*; D005971:Glutamates / Q000009:adverse effects*; D008297:Male; D051379:Mice; D039821:Monoterpenes / Q000627:therapeutic use*; D009020:Morphine / Q000627:therapeutic use; D009043:Motor Activity / Q000187:drug effects; D009294:Narcotics / Q000627:therapeutic use; D009431:Neural Conduction / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects*; D010146:Pain / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000187:drug effects; D018689:Sensory System Agents / Q000009:adverse effects*
D000080462:Acyclic Monoterpenes; D000447:Aldehydes; D000700:Analgesics; D005971:Glutamates; D039821:Monoterpenes; D009294:Narcotics; D018689:Sensory System Agents; D005557:Formaldehyde; D009020:Morphine; C108217:citronellal; D002211:Capsaicin