Differential responses by neurotensin systems in extrapyramidal and limbic structures to ibogaine and cocaine.
Brain research – February 06, 1999
Source: PubMed
Summary
A natural compound, ibogaine, shows promise in fighting stimulant addiction by altering brain chemistry. Researchers explored how ibogaine affects neurotensin, a brain messenger, and its interaction with cocaine. They administered drugs to observe neurotensin changes in key brain regions. Ibogaine significantly boosted neurotensin in reward and movement areas; this rise was blocked by specific dopamine receptor blockers. Crucially, ibogaine pretreatment successfully prevented the neurotensin surge caused by cocaine, suggesting neurotensin is vital to ibogaine's ability to counteract cocaine's brain effects.
Abstract
Ibogaine (Endabuse) is a psychoactive indole alkaloid found in the West African shrub, Tabernanthe iboga. This drug interrupts cocaine and amphetamine abuse and has been proposed for treatment of addiction to these stimulants. However, the mechanism of action that explains its pharmacological properties is unclear. Since previous studies demonstrated differential effects of psychotomimetic drugs (cocaine and methamphetamine) on neuropeptides such as neurotensin (NT), the present study was designed to determine: (1) the effects of ibogaine on striatal, nigral, cortical, and accumbens neurotensin-like immunoreactivity (NTLI); (2) the effects of selective dopamine antagonists on ibogaine-induced changes in NT concentrations in these brain areas; and (3) the effects of ibogaine pretreatment on cocaine-induced changes in striatal, nigral, cortical and accumbens NTLI content. Ibogaine treatments profoundly affected NT systems by increasing striatal, nigral, and accumbens NTLI content 12 h after the last drug administration. In contrast, NTLI concentrations were not significantly increased in the frontal cortex after ibogaine treatment. The ibogaine-induced increases in NTLI in striatum, nucleus accumbens and substantia nigra were blocked by coadministration of the selective D1 receptor antagonist, SCH 23390. The D2 receptor antagonist, eticlopride, blocked the ibogaine-induced increase in nigral NTLI, but not in striatum and nucleus accumbens. Ibogaine pretreatment significantly blocked the striatal and nigral increases of NTLI resulting from a single cocaine administration. Whereas many of the responses by NT systems to ibogaine resembled those which occur after cocaine, there were also some important differences. These data suggest that NT may contribute to an interaction between ibogaine and the DA system and may participate in the pharmacological actions of this drug.