Figure 8.
Short-duration combined yohimbine and imipramine treatment for 7 d upregulates the mRNA expression of plasticity associated genes like BDNF, VEGF, FGF-2, VGF, and Arc in the dentate gyrus. Rats received treatment with the α2-adrenoceptor antagonist, yohimbine and the antidepressant, imipramine for 7 d before kill and processing for in situ hybridization as described in Materials and Methods. In situ hybridization for BDNF, VEGF, FGF-2, VGF, Arc, and CREB transcripts was performed using specific riboprobes and transcript levels in the hippocampal DG subfield were quantified using densitometric analysis. A, C, E, G, I, K, Representative autoradiograms of hippocampal sections from vehicle-, yohimbine-, imipramine-, and yohimbine + imipramine-treated animals are shown for BDNF (A), VEGF (C), FGF-2 (E), VGF (G), Arc (I) and CREB (K) mRNA. Arrowhead indicates the DG (A). Levels of mRNA in the DG hippocampal subfield are shown in the bar graphs next to the representative autoradiograms. B, D, F, H, J, Levels of BDNF (B), VEGF (D), FGF-2 (F), VGF (H) and Arc (J) mRNA in the DG were significantly increased following 7 d combined yohimbine + imipramine treatment compared with vehicle-treated controls. K, L, CREB mRNA levels were unchanged following combination treatment with yohimbine and imipramine. Results are expressed as percentage of vehicle and are the mean ± SEM (n = 4/group). *p < 0.05 compared with vehicle, #p < 0.05 compared with yohimbine, $p < 0.05 compared with imipramine (ANOVA and Bonferroni post hoc test).