Influence of penicillin-induced epileptic activity during pregnancy on postnatal hippocampal nestin expression in rats: light and electron microscopic observations.

Objects: Current data concerning the effects of maternal epileptic phenomena on newborns are limited. In clinical practice, therefore, it is difficult to suggest proper guidelines on this issue. This study was carried out to investigate the morphological changes in the hippocampus of newborn pups of rats subjected to experimental epilepsy during pregnancy.

Methods: Eighteen Swiss Albino rats were randomly divided into three groups (n=6): experimental group, saline-injected sham surgery group, and intact control group. In the experimental group of rats, an acute grand mal epileptic seizure was induced by 400 IU penicillin-G administration into their intra-hippocampal CA3 region with a stereotaxic device during the 13th day of their pregnancy. On the first neonatal day, pups were perfused with intracardiac fixative solution under anesthesia, and newborn hippocampi were dissected surgically for light and electron microscopic examinations. In an immunohistochemical study using Rat-401 mono-clonal antibody and peroxidase, nestin expression was analyzed in the developing hippocampal tissue.

Results: Histologically, normal migration and hippocampal maturation were determined in the newborn rat hippocampus in the control and the sham-operated groups. It was observed that the morphological structure of hippocampus in the experimental group corresponded to the early embryonal period. Most importantly, it was found that nestin (+)cell density was increased in the experimental epilepsy group in contrast to the control and sham groups.

Conclusion: It has been concluded that epileptic seizures during embryonic life may cause impaired hippocampal neurogenesis and maturation,explaining the potentially harmful effects of epileptic seizures on the embryo at the early stage of neuronal differentiation. This is the first report regarding the alterations in nestin expression in newborn rat hippocampus. In the light of such findings, it will also be necessary to evaluate the functional consequences of a va-riety of epileptic seizures on learning and memory in neonates.