The Raman microspectroscopic study of epileptic tissue

Absence epilepsy is the neurological syndrome characterized by the pathological spike-and wave discharges present in the electroencephalogram, accompanying a sudden loss of consciousness. WAG/Rij rats, used in this study, are the well-established animal model of this pathology, which share epileptic symptoms with human patients suffering from absence seizures. Two different brain areas were specified: the somatosensory cortex (Sc) and dorsal lateral geniculate nucleus of the thalamus (DLG), considered as epileptic foci discharges. Experiments were performed on brain slices obtained from 2-3 weeks old WAG/Rij male rats, before the first episodes of seizures and Wistar rats as the control. No fixation method was used to prepare the samples. The Raman spectra of the fresh brain scraps kept in artificial cerebrospinal fluid, excited by 785 nm and 442 nm laser lines, were collected using a water immersive objective and StreamLine fast Raman imaging technique. A Principal Component Analysis (PCA) was used to evaluate the Raman data. Our studies showed differences in the spectra for the investigated groups of rats, indicating the presence of glial fibrillary acidic protein (GFAP) in the examined WAG/Rij brain regions. This study also assessed GFAP immunoreactivity in the brain tissue of healthy and epileptic rats.