Background: The aim of this study was to assess the effect of training, and noise stress on serotonin plasma level of Wistar rats.

Materials and Methods: For many years, physical activity have been used for the treatment of different neuropsychological dieases. Twenty one male witar rats (9-10 weeks old and 170.82±20.57g weight) were randomly divided into three groups: the noise group (n=7), training+noise group (n=7), and the control group (n=7). The aerobic training was performed 5 days per week, for a 60-day period. The noise stress included exposure to traffic noise 5 hrs/per day over a 60-day period (range:85-110 dB).The control group was not exposed to any noise or exercise, and was kept away from the sources of stress the rats were kept under the same conditions. At the end of the experiment, blood samples were collected and plasma serotonin concentrations were determined.For the statistical data analysis, one-way ANOVA and Tukey post-hoc tests were used (&alpha&le0.05).

Results: Plasma serotonin concentration significantly decreased in noise groups, in comparison with the controls (21.9±2.1, vs.40.8±7.3 &mumol/m, respectively p<0.000). The plasma serotonin levels in the noise +training groups (36.2±3.1) were apparently near to the controls However, resistance training could significantly increase plasma serotonin concentration in the noise+training group rats.

Conclusion: Increased serotonin level following resistance exercises might reduced stress in subjects.