The pheromone androstenol (5α-androst-16-en-3α-ol) is a neurosteroid positive modulator of GABA_a receptors

Androstenol is a steroidal compound belonging to the group of odorous 16-androstenes, first isolated from boar testes and also found in humans. Androstenol has pheromone-like properties in both animals and humans, but the molecular targets of its pheromonal activity are unknown. Androstenol is structurally similar to endogenous A-ring reduced neurosteroids that act as positive modulators of GABA_A receptors. Here we show that androstenol has neurosteroid-like activity as a GABA_A receptor modulator. In whole-cell recordings from cerebellar granule cells, androstenol (but not its 3β-epimer) caused a concentration-dependent enhancement of GABA-activated currents (EC₅₀, 0.4 μM in cultures; 1.4 μM in slices) and prolonged the duration of spontaneous and miniature inhibitory postsynaptic currents. Androstenol (0.1-1 μM) also potentiated the amplitude of GABA-activated currents in human embryonic kidney 293 cells transfected with recombinant α1β2γ2 and α2β2γ2 GABA_A receptors and, at high concentrations (10-300 μM), directly activated currents in these cells. Systemic administration of androstenol (30-50 mg/kg) caused anxiolytic-like effects in mice in the open-field test and elevated zero-maze and antidepressant-like effects in the forced swim test (5-10 mg/kg). Androstenol, but not its 3β-epimer, conferred seizure protection in the 6-Hz electroshock and pentylenetetrazol models (ED₅₀ values, 21.9 and 48.9 mg/kg, respectively). The various actions of androstenol in the whole-animal models are consistent with its activity as a GABA_A receptor modulator. GABA_A receptors could represent a target for androstenol as a pheromone, for which it is well suited because of high volatility and lipophilicity, or as a conventional hormonal neurosteroid.