Nicotinic-Muscarinic Interactions in Cognitive Function

Nicotinic and muscarinic receptor subtypes of the cholinergic system each have a long history of study. However, investigation has mainly concentrated on their separate actions. Their potential interactions have received very little attention, despite the fact that they both are stimulated by the same endogenous ligand. There are a variety of mechanisms by which these two types of cholinergic receptors might act in concert with regard to normal function, disease processes, and the effects of drugs and toxicants. In this chapter we review neurochemical, anatomical, and behavioral mechanisms for the interaction of nicotinic and muscarinic effects and what consequences these interactions may have on cognitive function. This oldest and best established case of receptor types for a single transmitter provides a good example of how the study of the function of such structures can easily get tracked into how they function separately, ignoring the critical investigation of how they interact.