How do sex and stress hormones affect nerve cells?

Gonadal and adrenal hormones regulate both structure and neurochemical function in neurons that express receptors for them. Gonadal hormone effects mediate sexual differentiation of the brain and reproductive tract, and their actions during early development program groups of cells in the nervous system to respond in male- or female-typical ways to hormones in adulthood. Induction of synapse formation is one consequences of brain sexual differentiation, but hormonally directed synaptic plasticity is by no means confined to early development and in fact occurs cyclically during reproductive cycles in a number of brain regions of the female rat, including the hippocampus. The hippocampus responds to adrenal steroids as well and undergoes changes in dendritic branching as a result of repeated stress. Implications of hormonally directed changes in brain structure and neurochemistry are discussed with respect to human pathophysiology.