Learning and cholinergic neurotransmission in old animals: the effect of Hydergine.

In the present work, a study of the number of functional receptors has been made with 3HQNB given to resting awaken animals during a learning process. Ageing leads to a decrease in the ability of learning associated with an increase in the number of large movements. The number of cholinergic receptors is also reducel if we compare 22 month old animals with 4 month old animals maintained under usual conditions. Learning conditioning leads to a stimulation of the cholinergic system with a release of acetylcholine. The mediator takes the 3HQNB out of its fixation areas which causes an apparent decrease in the number of receptors. This result is more significant in young animals than in aged ones because of the possibility of activation in the cholinergic system. The treatment by dihydroergotoxine partially re-establishes the learning abilities in animals and, at the same time, increases the number of cholinergic receptors This effect could explain the actions of this drug on the memory process in ageing persons.