Endogenous acetylcholine modulates impulsive action via α4β2 nicotinic acetylcholine receptors in rats

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Nicotine has been well established as an impulsive action-inducing agent, but it remains unknown whether endogenous acetylcholine affects impulsive action via nicotinic acetylcholine receptors. In the present study, the 3-choice serial reaction time task (3-CSRTT), a simple and valid assessment of impulsive action, was employed. Male Wistar/ST rats were trained to detect and respond to 1-s flashes of light presented in one of three holes until stable performance was achieved. Following training on the 3-CSRTT, rats received intracerebroventricular injections of the preferential α4β2 nicotinic acetylcholine receptor antagonist dihydro-β-erythroidine (DHβE; 0, 3, 10, and 30μg) or the selective α7 nicotinic acetylcholine receptor antagonist methyllycaconitine (MLA: 0, 3, 10, and 30 μg) 5 min before test sessions. Injection of 10 μg of DHβE significantly suppressed premature responses, an index of impulsive-like action, without changing other behavioral parameters. On the other hand, MLA infusions failed to affect impulsive-like action at any dose. These results suggest that the central α4β2 nicotinic acetylcholine receptors that enable a provoking effect of endogenous acetylcholine play a critical role in impulsive action. Substances that modulate nicotinic acetylcholine receptors, especially the α4β2 subtype, may be beneficial for the treatment of psychiatric disorders characterized by lack of inhibitory control.
2010-09-01