Schematic diagram of experimental design and procedures.

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

Methylphenidate and environmental enrichment ameliorate the deleterious effects of prenatal stress on attention functioning

<div><p></p><p>Either pre- or post-natal environmental factors seem to play a key role in brain and behavioral development and to exert long-term effects. Increasing evidence suggests that exposure to prenatal stress (PS) leads to motor and learning deficits and elevated anxiety, while enriched environment (EE) shows protective effects. The dopaminergic system is also sensitive to environmental life circumstances and affects attention functioning, which serves as the preliminary gate to cognitive processes. However, the effects of methylphenidate (MPH) on the dopaminergic system and attentional functioning, in the context of these life experiences, remain unclear. Therefore, we aimed to examine the effects of EE or PS on distinct types of attention, along with possible effects of MPH exposure. We found that PS impaired selective attention as well as partial sustained attention, while EE had beneficial effects. Both EE and MPH ameliorated the deleterious effects of PS on attention functioning. Considering the possible psychostimulant effect of MPH, we examined both anxiety-like behavior as well as motor learning. We found that PS had a clear anxiogenic effect, whereas EE had an anxiolytic effect. Nevertheless, the treatment with both MPH and/or EE recovered the deleterious effects of PS. In the motor-learning task, the PS group showed superior performance while MPH led to impaired motor learning. Performance decrements were prevented in both the PS + MPH and EE + MPH groups. This study provides evidence that peripubertal exposure to EE (by providing enhanced sensory, motor, and social opportunities) or MPH treatments might be an optional therapeutic intervention in preventing the PS long-term adverse consequences.</p></div