Early life LiCl-pilocarpine-induced status epilepticus reduces acutely hippocampal glutamate uptake and Na+/K+ ATPase activity

Abstract

Status epilepticus-induced hippocampal neuronal loss is mainly associated with excitotoxicity induced by increased levels of extracellular glutamate which is normally neutralized by high-affinity uptake mechanism. The energy source for the glutamate uptake is the electrochemical Na+ gradient maintained by Na+/K+ ATPase pump. In this study, we investigated the effect of early-life-induced status epilepticus on hippocampal Na+/K+ ATPase activity and glutamate uptake. Rat pups 15days old were injected i.p. with LiCl (3mEq/kg) 12–18h prior to s.c. pilocarpine administration (60mg/kg). Hippocampal Na+/K+ ATPase activity and glutamate uptake were evaluated 1.5, 12 and 24h after SE induction. LiCl-pilocarpine-induced SE decreased Na+/K+ ATPase activity and glutamate uptake by 42 and 38%, respectively, 1.5h after SE induction. However, 12 and 24h after SE induction the pump activity and glutamate uptake returned to control levels. SE early in life increased hippocampal number of degenerating neurons in the CA1 subfield and dentate gyrus 24h after SE induction. In conclusion, SE induced early in life causes short-term disruption in hippocampal Na+/K+ ATPase activity and glutamate uptake, which may be related to neuronal death found in CA1 subfield.