Effect of finasteride on behavioural arousal and somatosensory evoked potentials in fetal sheep

This study examines the effect of inhibiting the synthesis of gamma -aminob utyric acid(A) (GABA(A)) agonist steroids on behavioural activity and somat osensory evoked potentials (SEP) in late gestation fetuses. Pregnane steroi d production was suppressed by infusion of the 5 alpha -reductase inhibitor , finasteride in chronically catheterised fetal sheep, 130-135 days gestati on. Finasteride treatment (160 mg in 10 ml of vehicle over 2 h) significant ly increased the incidence of fetal arousal during the period 4-10 h after commencing the infusion (P < 0.05, n = 6), whereas other behavioural parame ters were not effected. In three of four animals, finasteride produced an i ncrease in the amplitude of the N22 peak of the SEP during high voltage ele ctrocortical activity. We conclude that suppressio n of pregnane steroid sy nthesis, by inhibition of the 5<alpha>-reductase enzyme, increases arousal activity in the fetus which is consistent with a reduction in GABA(A) recep tor mediated inhibition. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.