Increased expression of BDNF transcript with exon VI in hippocampi of patients with pharmaco-resistant temporal lobe epilepsy

A putative role of the brain-derived neurotrophic factor (BDNF) in epilepsy has emerged from in vitro and animal models, but few studies have analyzed human samples. We assessed the BDNF expression of transcripts with exons I (BDNFI), II (BDNFII), IV (BDNFIV) and VI (BDNFVI) and methylation levels of promoters 4 and 6 in the hippocampi of patients with pharmaco-resistant temporal lobe epilepsy (TLE) (n = 24). Hippocampal sclerosis (HS) and pre-surgical pharmacological treatment were considered as clinical independent variables. A statistical significant increase for the BDNFVI (p < 0.05) was observed in TLE patients compared to the autopsy control group (n = 8). BDNFVI was also increased in anxiety/depression TLE (N = 4) when compared to autopsies or to the remaining group of patients (p < 0.05). In contrast, the use of the antiepileptic drug Topiramate (TPM) (N = 3) was associated to a decrease in BDNFVI expression (p < 0.05) when compared to the remaining group of patients. Methylation levels at the BDNF promoters 4 and 6 were similar between TLE and autopsies and in relation to the use of either Sertraline (SRT) or TPM. These results suggest an up-regulated expression of a specific BDNF transcript in patients with TLE, an effect that seems to be dependent on the use of specific drugs.