TrkB expression in MTLE specimens with and without psychiatric comorbidities and in non-epileptic controls. MTLE (a) and MTLE + D (c) exhibited decreased TrkB expression in CA3 when compared to MTLE + P (b) and control group (d). We found TrkB immunoreactive area values (e) higher in the dentate gyrus of epileptic groups with psychiatric comorbidities, and decreased in other subfields of MTLE specimens when compared to controls (double asterisk, p < 0.01; single asterisk, p < 0.05). Differences among epileptic groups were seen in the granular layer, hilus, CA4, CA3, prosubiculum, subiculum, parasubiculum and entorhinal cortex, where MTLE specimens showed decreased TrkB expression when compared to MTLE with psychiatric comorbidities (single hash sign, p < 0.05; double hash sign, p < 0.01). Values from MTLE (black bars), MTLE + D (gray bars), MTLE + P (light gray bars) and from non-epileptic controls (white bars) are indicated as mean ± std. deviation. Scale bar (a-d): 50 μm.