Antinociceptive profile of (+)-citronellol in experimental animals

(+)-Citronellol, the natural occurring enantiomer monoterpene compound, is commonly found as a component of aromatic plants essential oil. Considering that several monotepenes have showed analgesic properties [1, 2], the aim of this study was to investigate the possible antinociceptive effect of (+)-citronellol on three different pain models, namely the acetic acid-induced writhing reaction [3], the hot-plate test [4], and the tail-flick model [5]. Indomethacine (7.5mg/kg; i.p.; p<0.001) and morphine (2.5mg/kg; i.p.; p<0.001) were used as positive control in the writhing and the hot-plate tests, respectively. (+)-Citronellol, at doses of 10, 25, and 50mg/kg (s.c.), dose-dependently reduced the writhing induced by acetic acid (p>0.05, p<0.01 and p<0.001, respectively) and increased the latency in the hot-plate test (p>0.05, p<0.05 and p<0.01, respectively). The (+)-citronellol-induced antinociception (50mg/kg; s.c.) in the hot-plate model was reversed by the opiate antagonist naloxone (3mg/kg; i.p.). Naloxone (3.0mg/kg; i.p.) was ineffective in the hot-plate method. Morphine (12mg/kg; i.p.; p<0.001) increased the reaction time in the tail-flick test. However, unlike morphine, (+)-citronellol did not manifest a significant effect in the tail-flick model (10–75mg/kg; s.c.). In conclusion, (+)-citronellol showed analgesic properties, involving the opioid system activation in a supra-spinal, but not a spinal, site of action. Since it was effective in the acetic acid-induced writhing model, a peripheral antinociceptive effect can not be disregarded.

Acknowledgments: CNPq.

References: 1. Peana, A.T. et al.(2003), Eur. J. Pharmacol. 460: 37–41. 2. Santos, F.A., Rao, V.S.N. (2000), Phytother, Res, 14: 240–244. 3. Koster, R. et al. (1959), Fed. Proc. 18: 412–418. 4. Ankier, S.I. (1974) Eur. J. Pharmacol. 27: 1–4. 5. Langerman, L. et al. (1995), Pharmacol. Toxicol. 34: 23–27.