Behavioral and biochemical effects of intracerebrally injected alkaloids.

Tetrahydroisoquinolines and beta-carbolines, substances which may form in the brain following the ingestion of alcohol, could be responsible for some of the behavioral effects of alcohol. When certain of these alkaloids are infused into the brain of the rat they induce an enhanced consumption of alcohol in a free-choice situation, both during infusion and for months after the cessation of infusion. In investigating the possible mechanism behind this permanent change in preference for alcohol, it does not appear that the post-synaptic side of the catecholamine neurons is involved. Likely candidates for future investigation include the pre-synaptic side of the catecholamine neurons and the serotonergic and opiate systems.