Glial Cell Line-Derived Neurotrophic Factor Mediates the Desirable Actions of the Anti-Addiction Drug Ibogaine against Alcohol Consumption

Ibogaine, a natural alkaloid with side effects that prevent clinical use, reduces alcohol consumption in rats. In two-bottle choice and operant self-administration tests, ibogaine decreased ethanol intake and also reduced relapse-like drinking. The effect is mediated by glial cell line-derived neurotrophic factor (GDNF) in the ventral tegmental area (VTA): ibogaine microinjected into the VTA reduced self-administration, systemic ibogaine increased GDNF expression in the midbrain, and in dopaminergic SHSY5Y cells ibogaine activated the GDNF pathway (phosphorylation of Ret and ERK1). Intra-VTA GDNF mimicked ibogaine's effect, while anti-GDNF antibodies blocked it. GDNF in the VTA therefore mediates ibogaine's action on ethanol consumption, suggesting GDNF as a target for alcoholism medications that could avoid ibogaine's side effects.

Study at a glance

Abstract

Alcohol addiction manifests as uncontrolled drinking despite negative consequences. Few medications are available to treat the disorder. Anecdotal reports suggest that ibogaine, a natural alkaloid, reverses behaviors associated with addiction including alcoholism; however, because of side effects, ibogaine is not used clinically. In this study, we first characterized the actions of ibogaine on ethanol self-administration in rodents. Ibogaine decreased ethanol intake by rats in two-bottle choice and operant self-administration paradigms. Ibogaine also reduced operant self-administration of ethanol in a relapse model. Next, we identified a molecular mechanism that mediates the desirable activities of ibogaine on ethanol intake. Microinjection of ibogaine into the ventral tegmental area (VTA), but not the substantia nigra, reduced self-administration of ethanol, and systemic administration of ibogaine increased the expression of glial cell line-derived neurotrophic factor (GDNF) in a midbrain region that includes the VTA. In dopaminergic neuron-like SHSY5Y cells, ibogaine treatment upregulated the GDNF pathway as indicated by increases in phosphorylation of the GDNF receptor, Ret, and the downstream kinase, ERK1 (extracellular signal-regulated kinase 1). Finally, the ibogaine-mediated decrease in ethanol self-administration was mimicked by intra-VTA microinjection of GDNF and was reduced by intra-VTA delivery of anti-GDNF neutralizing antibodies. Together, these results suggest that GDNF in the VTA mediates the action of ibogaine on ethanol consumption. These findings highlight the importance of GDNF as a new target for drug development for alcoholism that may mimic the effect of ibogaine against alcohol consumption but avoid the negative side effects.