Influence of pregnancy on blood-brain barrier integrity during seizures in rats

The effect of pregnancy on blood-brain barrier permeability was investigated during bicuculline-induced seizure in Wistar rats, using Evans-blue as a tracer. The experiments were carried out with two methods to investigate the integrity of the blood-brain barrier, i.e. Evans-blue albumin extravasation was determined as a macroscopical finding. A quantitative estimation with a spectrophotometer using homogenized brain to release the dye was performed to evaluate the macroscopical findings in a separate group of animals. During convulsions the mean arterial blood pressure increased in both pregnant and nonpregnant rats. The extravasation of Evans-blue was more pronounced in the nonpregnant rats. Mean values for Evans-blue dye were found to be 0.29 +/- 0.07 mg% whole brain in nonpregnant control female rats and 0.30 +/- 0.09 mg% whole brain in pregnant rats. This difference was not significant (P > 0.05). Mean values for Evans-blue dye were 1.02 +/- 0.30 mg% whole brain in nonpregnant female rats, and 0.60 +/- 0.12 mg% in the pregnant rats during bicuculline-induced seizures. This difference was significant (P < 0.01). The severe protein leakage was seen in the thalamus, midcaudate, hypothalamus and mesencephalon bilaterally in the nonpregnant rats. However, in pregnant rats, Evans-blue leakage was similar to that of female rats except that the intensity of blood-brain barrier breakdown was less after convulsion.