2.15 Statistical analysis
The data were statistically analyzed by SPSS 19.0 (IBM) and are expressed as the means ± SEMs. The experimental data were compared by one-way analysis of variance (ANOVA). A P value < 0.05 was considered statistically significant. The sample size needed for statistical analysis was determined to be at least 5 animals in each group (N=5, where n refers to the number of independent data points).