Vesicular glutamate transporters (VGLUTs) are responsible for loading
glutamate into synaptic vesicles. Altered VGLUT
protein expression has been suggested to affect quantal size and
glutamate release under both physiological and pathological conditions. In this study, we investigated
mRNA and
protein expression levels of the three VGLUT subtypes in hippocampal tissue of patients suffering from
temporal lobe epilepsy (TLE) with
hippocampal sclerosis (HS), International League Against
Epilepsy type 1 (ILAE type 1) compared to autopsy controls, using quantitative polymerase chain reaction and semi-quantitative western blotting.
mRNA expression levels of the VGLUTs are unaffected in hippocampal epileptic tissue compared to autopsy controls. At the
protein level, VGLUT1 expression remains unaltered, while VGLUT2 is significantly decreased and VGLUT3
protein is significantly increased in hippocampal biopsies from TLE patients compared to controls. Our findings at the
protein level can be explained by previously described histopathological changes observed in HS. Although VGLUTs have been repeatedly investigated in distinct rodent
epilepsy models, their expression levels were hitherto not fully unraveled in the most difficult-to-treat form of
epilepsy: TLE with HS ILAE type 1. We here, demonstrate for the first time that
VGLUT2 protein expression is significantly decreased and VGLUT3
protein is significantly increased in the hippocampus of patients suffering from TLE with HS ILAE type 1 compared to autopsy controls.