Schematic diagram of experimental design and procedures.

<p>Schematic diagram of experimental design and procedures.</p

The effect of MPH on sucrose preference test.

<p>Considerable variation in sucrose intake was observed between the groups. While significant long term anhedonia was detected in the EE group, MPH treatment following EE significantly recovers this effect. * <i>P</i><0.019 versus control; ** <i>P</i><0.0001 versus EE saline; n = 9 to 10 per group.</p

The effect of MPH on CORT and TST levels.

<p>A significant difference in CORT (A) and TST (B) levels was observed. MPH treatment significantly increased CORT level in the EE and EES groups (* P<0.0001; ** P<0.002 compared with their respective controls). TST level was similar across all groups, while MPH treatment increased TST level in both EE and EES groups (* P<0.001; ** P<0.012 compared with their counterpart controls). n = 9 to 10 per group.</p

The effect of MPH on PPI.

<p>Significant differences in PPI scores were observed. EE led to the highest PPI compared with all groups (<i>P</i><0.0001). Following MPH treatment, the EES group showed higher PPI compared with control (<i>P</i><0.0001) and stress (<i>P</i><0.001) groups. A panel of representative traces demonstrate the differences in maximal response inhibition (at pre-intensity of 69 dB) of all four groups, with and without MPH. n = 9 to 10 per group.</p

The effect of MPH on locomotor activity.

<p>A significant difference in distance (A) and velocity (B) were detected between the groups in the open field test. Rats exposed to MPH following EE showed the lowest distance and velocity. These effects were not related to differences in body weight (C). MPH treatment significantly increased freezing duration (D) compared to saline. Following EE, MPH led to the highest freezing duration. * <i>P</i><0.0001 versus control; ** a: <i>P</i><0.022, b: <i>P</i><0.008, c: <i>P</i><0.0001 versus EE saline; n = 9 to 10 per group.</p