Influence of various drugs on the voluntary intake of nicotine by rats.

The effects of the dopaminergic agonists (L-dopa, pergolide) and antagonists (haloperidol, clozapin) and a cholinergic agonist (tacrine) and antagonist (mecamylamine) on the voluntary intake of nicotine were investigated with the 2-bottle paradigm with the test drugs being dissolved directly in the drinking fluid of the animals. This method was found to be a reliable procedure to quickly screen compounds with specific sites of action in the brain for their effects on the voluntary intake of nicotine or perhaps other substances of abuse as well. L-dopa, pergolide and haloperidol did not affect the intake of nicotine, whereas tacrine increased it slightly and clozapine and mecamylamine markedly. These results indicate that blockade of nicotinic and dopaminergic D4 receptors partially reduce the desired effect of nicotine by forcing the animals to consume more of this substance. Copyright 2000 S. Karger AG, Basel