Dopaminergic and cholinergic antagonism in a novel-object detection task with rats

In a free-choice test, rats display a tendency to interact more with a nove l object than a familiar object. In the present report, we assessed the rol e of the dopaminergic and cholinergic systems in the expression of this nov elty detection. Rats were injected with a dopaminergic antagonist (sulpirid e, U-99194A, clozapine, or L-745,870) or a cholinergic antagonist (mecamyla mine or scopolamine) prior to the free-choice novel-object test. The dopami ne antagonists did not block novel-object detection. In contrast, scopolami ne, but not mecamylamine, reliably blocked the expression of novelty detect ion, indicating a role for muscarinic receptors. (C) 2001 Elsevier Science B.V. All rights reserved.