Antinociceptive Action of Cholinomimetics Evaluated with the Method of the Return of Corneal Anesthesia Induced with Procaine

The antinociceptive action of cholinomimetic agents has been extensively described in the literature using a variety of methods involving mechanical, termal or chemical stimulation. Tremorine, a cholinomimetic drug with tremorogenic activity, suppresses the responsiveness of mice to tail pinching (3). Arecoline shows an antinociceptive action in the tooth pulp test in the rabbit and in several tests in mice and rats (vocalization response, tail flick, tail pinching, hot plate, abdominal writhing)(8). Eserine and oxotremorine are active in the tail flick test in mice (4). Cholinomimetic show antinociceptive activity also when injected into the cerebral ventricles, or into various cerebral areas. This has been demonstrated by Metys et al. (8) for carbachol and oxotremorine and by Pedigo et al. (9) for acetylcholine (ACh). The antinociceptive action of cholinomimetics is abolished by atropine or by other anticholinergic drugs but is not influenced by methyl-atropine. According to some authors, narcotic antagonists also are able to oppose this effect of cholinergics (4,9).