The effect of progesterone on the spontaneous interictal spike evoked by the application of penicillin to the cat's cerebral cortex.

The effect of intravenous infusion of progesterone and Mebumal (ACO, Sweden; penotobarbital, INN) on the frequency and amplitude of the spontaneous interictal spikes from a penicillin focus in the cerebral cortex was investigated in ovariectomized cats anaesthetized with chloralose. The plasma concentration of progesterone was determined. It was found that the generation of penicillin spikes was depressed by progesterone in plasma concentrations as low as 40 ng/ml. Equimolar doses of Mebumal were less effective.