Fig. 1.

This schematic shows how estradiol and testosterone regulate the LC-NE system. Estradiol enhances NE activity by increasing NE production in LC neurons (blue), decreasing COMT-dependent NE degradation, and reducing presynaptic adrenergic receptors that inhibit NE release. As a possible compensatory action, estradiol also reduces adrenergic receptors on postsynaptic neurons (green). In contrast, testosterone reduces TH, the NE synthetic enzyme, while increasing presynaptic adrenergic receptors that inhibit NE release. DA dopamine, DBH dopamine β-hydroxylase, DOPA l-dihydroxyphenylalanine, COMT catechol-O-methyltransferase, NE norepinephrine