The Na+/K+ ATPase activity is increased in the hippocampus after multiple status epilepticus induced by pilocarpine in developing rats

The effects of repetitive pilocarpine-induced status epilepticus (SE) in the hippocampal Na+/ K(+)ATPase activity were studied in developing rat. Na+/KATPase is a membrane-bound enzyme responsible for the active transport of sodium and potassium ions through the membrane. It is necessary to maintain neuronal excitability. The malfunction of this enzyme has been associated with neuronal hyperexcitability. The pilocarpine-induced status epilepticus in developing rats leads to neuronal hyperexcitability and brain damage. We examined the activity of the Na/K+ ATPase enzyme in hippocampus of rats submitted to 1 episode of status epilepticus on postnatal day 9 and to 3 episodes of pilocarpine-induced status epilepticus on postnatal days 7, 8 and 9. Our findings showed that one status epilepticus episode does not modify the Na+/K(+)ATPase activity in hippocampus of rats studied 7 or 30 days later (at P16 or P39). However, an increase in the Na+/K(+)ATPase activity was detected in hippocampus of rats submitted to three consecutive status epilepticus during the development studied 7 (+ 142%) and 30 (+400%) days following the injections. in addition, a significant reduction in the Na+/K(+)ATPase activity was observed in control rats at P39 compared to P16. Our data suggest that multiple pilocarpine -induced status epilepticus in developing rats induce long-lasting increase in the Na+/K(+)ATPase activity in the hippocampus, reflecting hyperexcitability. (c) 2007 Elsevier B.V. All rights reserved.