Different Synaptic Stimulation Patterns Influence Local Androgenic and Estrogenic Neurosteroid Availability Triggering Hippocampal Synaptic Plasticity in Male Rats

The study investigated how local synthesis of 17β-estradiol (E2) and 5α-dihydrotestosterone (DHT) influenced synaptic plasticity in the hippocampal CA1 region of male rat brain slices. Using electrophysiological recordings, the researchers examined long-term depression (LTD) and long-term potentiation (LTP) under the inhibition of DHT synthesis by finasteride (FIN) and E2 synthesis by letrozole (LET). They found that blocking DHT synthesis with FIN converted LTD into LTP and enhanced LTP, effects that were reversed by exogenous DHT. Inhibition of E2 synthesis reduced LTP amplitude, while exogenous E2 either enhanced LTP or converted LTD into LTP. The study concluded that the availability of E2 and DHT, combined with specific synaptic stimulation patterns, determined the sign and amplitude of long-term synaptic effects.