Protein expression of P-glycoprotein in neocortex from patients with frontal lobe epilepsy

Frontal lobe epilepsy (FLE) is the second most frequent type of epilepsy and the surgical outcome depends on the etiology. For instance, patients with posttraumatic FLE (PTE) have a worse surgical outcome compared to patients with FLE related to a tumoral lesion (TL). The present study focuses to determine if the FLE etiology is associated with the P-glycoprotein (P-gp) expression, a condition associated with drug resistance. P-gp expression and cellular localization were determined by Western Blot and immunohistochemical experiments in cortical brain samples obtained from patients with PTE (n = 5), TL (n = 5), and autopsies (n = 5). The neuronal count was estimated by Nissl and stereology procedure. Results showed that the autopsies tissue showed a neuronal count of 3514 ± 304.2 neurons per mm³. The P-gp expression ratio was 0.33 ± 0.02. Its expression was found in endothelial cells. Negligible P-gp expression was detected in neurons and astrocytes. Compared to the autopsies group, the TL group showed no changes in the neuronal count but, there was a decreased P-gp expression ratio (46%, p < 0.05). P-gp was located mainly in neurons, slight in astroglial, and endothelial cells. The PTE group showed a similar P-gp expression ratio compared to the autopsies group. P-gp was expressed in neurons, astrocytes, and endothelial cells in these samples. However, experiments revealed a high P-gp expression in a lower neuronal count (38%, p < 0.05 vs autopsy group). The present study reveals that patients with PTE present neuronal P-gp overexpression. This finding could underlie their worst surgical outcome.