Reversal of hippocampal sexual dimorphism by gonadal steroid manipulation

Hippocampal slices display a sexually dimorphic pattern of physiological neuromodulation to gonadal steroid administration. To determine if this is the result of organizational or activational hormone action, plasma steroid levels of adult male rats were manipulated. The results support an activational mechanism since steroid levels can be manipulated to abolish, reverse, or maintain the functional dimorphism. The results suggest a role for gonadal steroid action in rapid neuromodulation of brain function.