Progressive heart P-glycoprotein (P-gp) overexpression after experimental repetitive seizures (ERS) associated with fatal status epilepticus (FSE): Is it related with SUDEP?

Abstract

Patients with refractory epilepsy (RE) have increased risk of Sudden Unexpected Death in Epilepsy (SUDEP), where acute and fatal heart failure is suspected. High seizure frequency, polypharmacy, changes in dosing, persistent low AED levels or poor adherence to therapy are the greatest risk factors of SUDEP and are also features observed in RE. We evaluated the progressive P-gp overexpression in heart, related with the development of fatal status epilepticus (FSE) after experimental repetitive seizures (ERS). Male Wistar rats (180–230g) were daily injected (i.p) with Pentylenetetrazole (PTZ; 45mg/kg; n=18) or saline (Controls; n=6). Severity of seizures was recorded. Four PTZ-treated rats were sacrificed at 4th-7th day respectively. Ten remaining rats, underwent same treatment until develop fatal status epilepticus (FSE). Brains and hearts were studied by immunofluorecent method for P-glycoptrotein (P-gp) expression. Seizures were observed each day of PTZ treatment, associated with a progressive P-gp overexpression in heart and FSE at 9th day. Using the same PTZ model, we previously demonstrated that progressive brain P-gp overexpression contributes to cell membrane depolarization of hippocampus and neocortex. These are the first evidences showing that ERS induces a simultaneous and progressive P-gp overexpression in brain and heart associated with FSE, and suggests a role for this pattern expression of P-gp as risk factor for death during SE. The simultaneous and spontaneous death of all animals during SE observed only at day 9th, suggest that a higher P-gp overexpression in cardiomyocytes could play a role in SUDEP, however, because it is only a study descriptive, further researches are needed to confirm this hypothesis.