Acute Stress Increases Depolarization-Evoked Glutamate Release in the Rat Prefrontal/Frontal Cortex: The Dampening Action of Antidepressants (original) (raw)
Figure 6
The synaptic facilitation and its Ca2+-dependence are significantly reduced in footshock stressed rats and the effect is efficiently prevented by desipramine pre-treatment.
A) Specimen paired-pulse eEPSCs at increasing Ca2+ concentrations were obtained in vehicle-treated (CNT) and subjected to FS-stress (Stress) rats by stimulating layer V at a time interval of 50 ms and recording from pyramidal neurons. B) The mean paired-pulse ratio (PPR) of the second to the first eEPSC in neurons from vehicle-treated (CNT) (closed squares; n = 11), subjected to FS-stress (Stress) (open circles; n = 11), chronically treated with DMI (DMI) (closed triangles; n = 9) and chronically treated with DMI and then subjected to FS-stress (DMI+Stress) (open triangles; n = 10) rats were plotted as a function of the inter-stimulus interval (from 10 to 250 ms). PPR, at all tested intervals, were significantly lower in cells from FS-stressed rats than in neurons from all the other groups (*p<0.05, Bonferroni post-hoc tests following two-way ANOVA). C) PPR calculated at 50 ms inter-stimulus interval clearly decreased with increasing Ca2+ concentrations in neurons of vehicle-treated (CNT) (n = 6), chronically treated with DMI (DMI) (n = 8) and chronically treated with DMI and then subjected to FS-stress (DMI+Stress) (n = 9) rats. On the contrary, neurons from FS-stress rats (n = 6) showed a lower sensitivity to the changes in external Ca2+ concentration (*p<0.05, FS-stressed vs all the other groups, Bonferroni post-hoc tests following two-way ANOVA). D) Representative eEPSCs traces recorded in vehicle-treated (CNT) (black trace) and subjected to FS-stress (Stress) (grey trace) rats, showing the rise and decay kinetics fitted by mono-exponential curves. E,F) Rise (E), and decay (F) times (means±SEM) of eEPSCs estimated in neurons obtained from vehicle-treated (CNT) (n = 11), subjected to FS-stress (Stress) (n = 11), chronically treated with DMI (DMI) (n = 8) and chronically treated with DMI and then subjected to FS-stress (DMI+Stress) (n = 8) rats. *p<0.05; **p<0.01, Bonferroni post-hoc tests following two-way ANOVA.