Early consequences of lithium-pilocarpine convulsive status epilepticus (SE) were studied six days after this status had been induced in rat pups at the age of either 12 or 25 days. Studies of spontaneous EEG activity demonstrated the presence of epileptic phenomena (isolated spikes) in both hippocampus and cortex (cortical spikes were more expressed in the older group). There were no marked behavioral correlates of spikes and transition into the ictal phase was exceptional. The motor performance on a rotorod and a horizontal bar was the same in experimental and control rats of both ages. Behavior in the open field was changed in a reverse manner in the two age groups: the locomotor activity of rats with induced seizures at the age of 12 days was significantly lower than that of their control siblings, whereas animals undergoing status at the age of 25 days were hyperactive. In addition, they also exhibited increased exploratory activity (rearing) and their habituation to the open field was deranged. Nissl-stained brain sections demonstrated extensive brain damage in the older group in contrast to the negative findings in younger animals. EEG, behavioral and morphological changes induced by status epilepticus in developing rats persisted for 6 days after the status. They markedly differed according to the age of animals., L. Suchomelová, H. Kubová, R. Haugvicová, R. Druga, P. Mareš., and Obsahuje bibliografii
Anticonvulsant action of vigabatrin (300, 600, 900 and/or 1200 mg/kg i.p.), an inhibitor of GABA-transaminase, was studied in a model of motor sezures elicited by pentylenetetrazol. Five age groups of rats (7, 12, 18, 25 and 90 days old) received a s.c. injection of pentylenetetrazol 4, 6 and/or 24 hours after vigabatrin administration. The incidence of minimal, predominantly clonic seizures was not changed in any age group, but their latencies were prolonged in 18- and 25-day-old rats. Generalized tonic-clonic seizures were influenced in a more complex manner. Incidence of these seizures was decreased in 7-day-old rat pups 24 hours after vigabatrin administration. Higher doses of vigabatrin exhibited a similar effect in adult rats at all intervals studied. Specific suppression or at least restriction of the tonic phase was observed in all groups of immature rats, the effect was more marked 24 hours after vigabatrin than at shorter intervals. The anticonvulsant action of vigabatrin, which could be demonstrated mainly against generalized tonic-clonic seizures, varies markedly during development., R. Haugvicová, H. Kubová, P. Mareš., and Obsahuje bibliografii
Local application of four concentrations of bicuculline methiodide (a specific antagonist of GABAA receptors) was used to study a sensitivity of somatosensory cortex in four age groups of immature rats with implanted electrodes. Presence and latencies of two epileptic phenomena (focal discharges and seizures) were evaluated. Focal discharges exhibited moderate tendency to a decrease of sensitivity to bicuculline methiodide with maturation. Concentration-effect relation of incidence of focal discharges was observed only in 7- and 12-day-old but not in older animals. Results with incidence and latencies of seizures did not show relations to age or concentration of bicuculline. Neither of the epileptic phenomena can be used as a reliable index of cortical maturation., P. Mareš, K. Bernášková, H. Kubová., and Seznam literatury