Fig. 8. BDNF-overexpression alters KCC2 mRNA expression and GABA_A receptor-evoked responses in E18 transgenic embryos. (A) Semiquantitative RT-PCR analysis showing the expression levels of KCC2 mRNA in two wild-type (control) and two transgenic (BDNF) forebrains. Note the marked increase in KCC2 mRNA levels in BDNF-overexpressing embryos compared to controls. GAPDH RT-PCR analysis was used as reference. (B,C) Non-radioactive in situ hybridizations illustrating neuronal somata expressing consistent levels of KCC2 mRNA through the hippocampus of transgenic BDNF-overexpressing embryos (C), whereas KCC2 mRNA expression levels in the control hippocampus are close to background (B). (D,E) Plot of F/F over time illustrating representative examples of GABA_A-evoked responses in wild-type (control) and transgenic (BDNF) neurons from E18 hippocampal slices. Administration of 10 µM muscimol (arrows) caused a [Ca²⁺]_i increase in both control and transgenic neurons, although the response was impaired in BDNF-overexpressing embryos (E). (F) Histograms representing the percentage of neurons responding to muscimol by [Ca²⁺]_i increase and the F/F amplitude in control (white bars) and BDNF-overexpressing hippocampi (black bars). Values are mean ± s.e.m. Scale bar: 200µm. *P<0.0001. Abbreviations as in Fig. 1.