Antinociceptive activity of coniine in mice

Hemlock was used as an analgesic in certain ethnopharmacological traditions and there has been no record about the antinociceptive effect of coniine which is the major alkaloid compound of Hemlock.

The present study was undertaken to evaluate the possible antinociceptive activity of coniine.

Antinociceptive activity of coniine was tested dose in Hotplate test (thermal pain model) and in Writhing test (chemical pain model) in different nociception models.

Coniine caused a prolongation in reaction time in Hotplate test at 20mg/kg dose. In addition, it was observed that coniine decreased the number of writhes in Writhing test. Both data indicated an antinociceptive effect of coniine. A rotarod test was also conducted in order to clarify, whether this activity was related with a loss of locomotion or with an analgesic activity. None of the chemical agents at those doses used in experiments caused a loss of locomotor activity. It was also shown that antinociceptive effect of morphine was potentialized by coniine which was inhibited by nicotinic receptor blocker mecamylamine (1mg/kg).

Coniine has antinociceptive effect via the nicotinic receptors. A pharmacological assessment about the painless death of Socrates due to Hemlock (coniine) toxicity has also been presented by using this data.