Neuroactive steroids are endogenous neuromodulators, synthesized de novo in the brain as well as adrenal glands, ovaries, and testes (see Biggio and Purdy 2001 for review). Among these compounds, the 3α,5α- and 3α,5β-reduced metabolites of progesterone (Majewska et al. 1986; Morrow et al. 1987), deoxycorticosterone (Majewska et al. 1986; Morrow et al. 1987), dihydroepiandrosterone (DHEA) (Frye et al. 1996; Kaminski et al. 2005; Park-Chung et al. 1999), and testosterone (Kaminski et al. 2005, 2006) enhance GABAergic neurotransmission. Their systemic administration induces anxiolytic, anticonvulsant, sedative-hypnotic, and cognitive-impairing effects, similar to other GABAA receptor positive modulators and ethanol (see Morrow et al. 2006 for review).
