Learning induces changes in the central cholinergic system of the rat in a sexually dimorphic pattern.

The involvement of the central cholinergic system in learning and the possible sexual dimorphism in related brain responses were investigated. Rats were exposed to different environmental conditions and to active avoidance learning. The resulting changes were studied using the following approaches: muscarinic receptor binding (MRB), acetylcholinesterase (AChE) and choline acetyltransferase (CAT) activities. The statistical evaluation of the data reveal that learning induces changes, especially in the postsynaptic component of the central cholinergic system, which shows some sexual dimorphism, and that males and females respond with different levels of increased cholinergic activity to informal and associative learning.