Figure 2
METH-induced hyperthermia and short-term effects of binge METH on the levels of ORF-1 mRNA in the rat brain.
Adult male Sprague-Dawley rats were administered saline (1 mL/kg) or binge METH (4 × 10 mg/kg, i.p. every 2 h) and killed 24 h later. (A) METH-induced hyperthermia. Core body temperatures (°C) were measured before treatments and 1 h after each METH or saline injection. The black arrows indicate the injection times. Binge METH induced significant hyperthermia during the treatment (***p < 0.001, two-way ANOVA with repeated measures followed by the Student-Newman-Keuls post hoc test, n = 4–7/group). (B) Short-term effect of binge METH on the levels of ORF-1 mRNA in rat brain. Compared with the controls, METH significantly increased ORF-1 mRNA levels in the striatum (1.8-fold, *p < 0.025) and the dentate gyrus (2.3-fold, **p < 0.01) (Student’s two-tailed t-test followed by the Bonferroni correction, n = 4–6 rats/group) at 24 h after METH administration. The data were normalized to the saline controls. (C) Short-term effect of binge METH on LINE-1 promoter methylation in the rat brain. The first ten CpG sites within the promoter region of LINE-1 were analyzed for methylation status (%). A small (−1%) but significant (p < 0.05, Student’s two-tailed t-test, n = 5–7 rats/group) decrease in the average methylation of these sites was observed in the dentate gyrus of binge METH-exposed rats. The decrease was due to the hypomethylation of CpG9 and CpG3 (−3.5%, ****p < 0.0001 and −1.9%, *p < 0.005, respectively, Student’s two-tailed t-test followed by the Bonferroni correction for multiple comparisons, n = 5–7 rats/group). The data are expressed as the mean ± SEM. Abbreviations: ave, average; CpG, cytosine guanine dinucleotide; h, hours; METH, methamphetamine; mRNA, messenger ribonucleic acid; SAL, saline.
