Rats with cobalt epilepsy in the estrous cycle revealed fluctuation of the levels of inhibitory neurotransmitters (especially GABA), but not of excitatory. The most significant changes were found out in the contralateral cortex, where the levels of GABA and glycine considerably decreased during the diestrus-2 phase (corresponding to menstruation). Neurophysiology characteristics indicate the increasing of epileptic activity mainly in the contralateral cortex during the diestrus-2 phase. These data indicate a close interaction between the ovarian hormonal system and the GABA-ergic system in the mechanisms of seizures states. Cyclical fluctuations of steroid hormones are of essential meaning for the course of epilepsy during the menstrual cycle.
