[Models for the study of memory and neurosteroids].

The steroids dehydroepiandrosterone sulfate (DHEA-S) and pregnenolone sulfate (Preg-S) are naturally synthetized in the brain. They improve short term and long term memory performances in a variety of learning tasks and models of amnesia in rodents. DHEA-S and Preg-S modulate GABAergic and glutamatergic synaptic transmission through direct interactions with GABA-A, NMDA and/or sigma 1 membrane receptors. In addition, these two neurosteroids facilitate the release of acetylcholine and modulate synaptic plasticity phenomena in cerebral structures, such as the hippocampus, known to play a role in learning and memory processes. The possible links between these actions and the promnestic effects of DHEA-S and Preg-S are discussed in the present review.