Kindling
It was reported that the generalized seizure triggering threshold in a group of pregnant amygdaloid kindled rats was significantly higher than that of a nonpregnant control group, which suggested that the physiological changes during pregnancy increased the seizure threshold.
Abstract
At the 17th annual meeting of the Japan Epilepsy Society, we reported that the generalized seizure triggering threshold in a group of pregnant amygdaloid kindled rats was significantly higher than that of a nonpregnant control group. This result suggested that the physiological changes during pregnancy increased the seizure threshold. In order to understand the pharmacological effect of the changes on the seizure threshold during pregnancy, we investigated the generalized seizure triggering threshold of pregnant rats receiving chronic PB medication orally. Some 20 adult female Wistar rats weighing 150g to 200g at the start of the experiment were used. Ten days prior to the beginning of the experiment, bipolar stimulating-recording electrodes were stereotaxically implanted in the left amygdala. The kindling stimulations consisted of a one-sec train of 60 Hz biphasic pulses (suprathreshold for afterdischarge) delivered to the left amygdala until five consecutive full convulsive seizures were achieved. The drug administration was initiated after the animals were fully kindled. This was conducted through an oral cannula, 4 mg/kg of a 0.4% phenobarbital elixir (Phenobal syrup; Fujinaga Pharmacy Co., Japan). As the drug doses are determined on the basis of dosage (mg) per body weight (gram), those increases were in respect with the increasing body weight during pregnancy. After they received PB for 14 days, the generalized seizure triggering threshold was determined, and then the animals were crossed. The generalized seizure triggering threshold was measured on the 7th, 14th and 21st day of the gestational period. The threshold of nonpregnant female rats (N = 10) was also measured at the start of the experiment and on the same days of the pregnant group, which were designated as the control group. The mean values expressed as the difference of threshold before crossing and that in each period during pregnancy are shown in Table 1. The mean value on the 7th day of the gestational period was slightly higher than that before crossing. The mean values on the 14th and 21st day of the gestational period were slightly lower than those before crossing. On the other hand, they were much lower than the threshold before crossing in the non-pregnant group. A statistical analysis showed that the mean values of the pregnant group were significantly higher than those of the non-pregnant group. (p < 0.01 is on the 7th day, p < 0.01 is on the 14th day, and p < 0.05 is on the 21st day). The threshold on the 7th day after delivery was