Citronellal, a monoterpene present in Java citronella oil, attenuates mechanical nociception response in mice

Context: Citronellal is a monoterpene present in the oil of many species, including Cymbopogon winterianus Jowitt (Poaceae).

Objective: The present study investigated the effect of citronellal on inflammatory nociception induced by different stimuli and examined the involvement of the NO-cGMP-ATP-sensitive K⁺ channel pathway.

Materials and methods: We used male Swiss mice (n = 6 per group) that were treated intraperitoneally with citronellal (25, 50 or 100 mg/kg) 0.5 h after the subplantar injection of 20 μl of carrageenan (CG; 300 µg/paw), tumor necrosis factor-α (TNF-α; 100 pg/paw), prostaglandin E₂ (PGE₂; 100 ng/paw) or dopamine (DA; 30 μg/paw). The mechanical nociception was evaluated at 0.5, 1, 2 and 3 h after the injection of the agents, using a digital analgesimeter (von Frey). The effects of citronellal were also evaluated in the presence of L-NAME (30 mg/kg) or glibenclamide (5 mg/kg).

Results: At all times, citronellal in all doses inhibited the development of mechanical nociception induced by CG (p < 0.001 and p < 0.01) and TNF-α (p < 0.001, p < 0.01, and p < 0.05). The citronellal was able to increase the pain threshold in the DA test (p < 0.001, p < 0.01, and p < 0.05) and in the PGE₂ test at all times (p < 0.001 and p < 0.05). L-NAME and glibenclamide reversed the antinociceptive effects of the citronellal at higher doses in the PGE₂ test.

Discussion and conclusion: These data suggest that citronellal attenuated mechanical nociception, mediated in part by the NO-cGMP-ATP-sensitive K⁺ channel pathway.