The development and expression of locomotor sensitization to nicotine in the presence of ibogaine.

Ibogaine, a naturally occurring psychoactive alkaloid reported to block nicotinic receptors, was tested for its ability to alter sensitization to nicotine's locomotor stimulant effect in rats. Over 21 days, rats received daily co-administration of ibogaine (0, 5, or 10 mg/kg) with nicotine (0 or 0.4 mg/kg). Nicotine alone produced clear sensitization—enhanced locomotor activity upon repeated exposure—but co-administration of ibogaine did not affect the degree of sensitization. Ibogaine alone (5–20 mg/kg) did not influence locomotor activity and did not alter the expression of the already-sensitized response to nicotine. The results provide no evidence that ibogaine retards or suppresses sensitization to nicotine.

Study at a glance

Abstract

Ibogaine is a naturally occurring psychoactive alkaloid with claimed efficacy in the treatment of certain drug addictions, including nicotine. It has been reported to be a non-competitive blocker of nicotinic receptors, with a potent inhibitory action on nicotinic acetylcholine receptor-mediated catecholamine release. We have investigated the effect of different doses of ibogaine on the development and expression of sensitization to the locomotor stimulant effect of nicotine in rats, a facilitatory process in which a history of exposure to nicotine results in enhanced locomotor activity when the same dose of nicotine is administered repeatedly. The effects were determined of co-administering ibogaine (0.0, 5.0 or 10 mg/kg i.p.) with nicotine (0.0 or 0.4 mg/kg s.c.) daily for 21 days. Dose-response curves for nicotine (0.04-0.8 mg/kg s.c.) were then determined in groups of 10 rats. There was clear sensitization of the locomotor activity produced by nicotine in photocell activity cages but co-administration of ibogaine with nicotine had no effect on the degree of sensitization. Ibogaine (5-20 mg/kg) itself did not influence locomotor activity and was also without effect on the expression of the sensitized response to 0.4 mg/kg of nicotine (n = 10). Thus, there was no evidence that ibogaine may retard or suppress sensitization to nicotine.