Fig. 7. GAD_65/67 expression and GABAergic synaptic contacts are greater in the E18 BDNF-overexpressing hippocampus. (A,B) Non-radioactive in situ hybridization showing the expression patterns of GAD_65/67 in the embryonic wild-type (A) and transgenic (B) hippocampus at E18. Note the increased hybridization signals in the transgenic hippocampus. (C) Northern blot analysis of E18 forebrain showing a 3-fold increase in GAD₆₇ mRNA expression in transgenic embryos (BDNF) compared to control embryos (C). Cyclophylin mRNA levels were used as an internal standard. (D,E) High magnification photomicrographs illustrating calbindin-immunopositive interneurons (arrows) in the stratum oriens of control (D) and transgenic (E) E18 hippocampi. Note the larger calbindin-positive neurons in the BDNF transgenic embryos compared to controls (arrows). (F-H) Electron microphotographs showing GABA immunogold labeling (arrows) in the stratum radiatum of E18 wild-type (F,G) and transgenic (H) hippocampus exhibiting GABA-positive (F,H) and GABA-negative (G) axon terminals (AT) with dendrites (D). (I,J) Histograms representing the greater number of GABA-positive axon terminals (I) and GABA-negative axon terminals (J) in BDNF-overexpressing hippocampus (black bar) than in wild-type hippocampus (white bar). *P<0.05; **P<0.001. Scale bars: 300 µm (A,B); 20 µm (D,E); 0.4 µm (F,G). Abbreviations as in Fig. 1.

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