Figure 2.

Runners exhibit increases in hippocampal GABAergic measures in response to cold water swim stress. These mice ran or were sedentary for 6 weeks, were exposed to cold water swim, and were either perfused 2 h later for immunolabeling or subjected to in vivo microdialysis for measurement of extracellular GABA. A, Following cold water swim stress, runners exhibit a greater percentage of GABAergic interneurons (GAD67 or PV positive) that express c-fos in the ventral dentate gyrus than sedentary mice. B, Confocal images of c-fos (green) colabeled with GAD67 (red, top) and PV (red, bottom). C, No differences were detected in the number of GAD67+ or PV+ cells in the dentate gyrus between runners and sedentary mice. D, Cold water swim stress produces greater extracellular GABA in the ventral dentate gyrus of runners compared with sedentary mice. E, Runners exhibit greater expression of vGAT, but not VGLUT1, throughout the dentate gyrus compared with sedentary mice. F, Confocal images of VGAT and VGLUT1 expression in the dentate gyrus of stressed sedentary and runner mice. Error bars represent SEM. *p < 0.05. ml, Molecular layer. Scale bars: in B, 10 μm; in F, 20 μm.