Abstracts

The aim of the present study is to investigate the influence of hyperthermia on the integrity of blood-brain barrier (BBB) in rats with cortical dysplasia., In this study, 32 one month old baby Sprague-Dawley rats were used for sodium fluorescein (NaFlu) staining method and 72 more animals were used for other parameters in parallel groups. Study groups consist of a control (8), cortical dysplasia (8), hypertermia (8) and cortical dysplasia and hyperthermia (8) groups. The pregnant rats which have been given sodium pentobarbital anesthesia with the dose of 30 mg/kg intraperitonally, were administered gamma irradiation of 145 cGy from the uterus on day E 17. To induce hyperthermia (39.5[plusmn]0.5[deg]C), rats were exposed to an elevated ambient temperature (55-60[deg]C) for 30 minutes. Vital signs such as body temperature and arterial blood pressure were also recorded. Immunohistochemistry and Western blot methods were used to show any alterations in occludin protein, and electron microscopy was performed to evaluate structural properties of BBB in this experiment. On the day of the experiment there was no mortality in hyperthermic animals., Blood pressure levels of rats with hyperthermia and rats with hyperthermia as well as cortical dysplasia increased significantly when compared to control values. Seizures the rats had were observed clinically; the longer the duration of hyperthermia was, the more seizures were seen. Both hyperthermia and cortical dysplasia did not change BBB permeability to NaFlu. Hyperthermia induced a generalized increase in BBB permeability to NaFlu in rats with cortical dysplasia and the highest increases ([gt] 130% over control values) were recorded in diencephalon and cerebellum regions. Western blot analysis of brain capillaries showed that the expression of the transmembrane tight junction protein occludin was not changed in response to dysplasia and hyperthermia., These results indicate that immature rats are resistant to hypertermic BBB disruption. However, hyperthermia may induce significant BBB permeability increase under cortical dysplastic conditions. We conclude that cortical dysplasia as an underlying pathology could increase the disruption of BBB integrity during hyperthermia.,