Time-dependent increase in methamphetamine brain levels in adult zebrafish waterborne exposed to 40 mg/L methamphetamine (METH) for 3 and 48 h and anxiety-like behavior, assessed in standard 6-min novel tank test (NTT) of zebrafish exposed to the same concentration and times. Data from each experiment were normalized to the corresponding control values. The combined data is reported as scatter plot with the median (n = 6–8 for METH levels in the brain and n = 14–15 for the NTT results), **p < 0.01, ***p < 0.001; Student’s t-test for METH levels in brain and Kruskal Wallis test with Bonferroni correction for NTT endpoints. Data from two independent experiments.

Increased motor activity in fish waterborne exposed to 40 mg/L methamphetamine. The total distance (m) moved during the first hour of the exposure for control fish and exposed fish was measured for each individual fish in shoals of six animals. Data reported as scatter plot with the median (n = 12), ***p < 0.001; Student’s t-test. Data from two independent experiments.

Anxiety-like behavior, assessed in standard 6-min dark-light test (DLT), in adult zebrafish waterborne exposed to 40 mg/L methamphetamine (METH) for 3 and 48 h. Data from each experiment were normalized to the corresponding control values. The combined data is reported as scatter plot with the median (n = 15–18), *p < 0.05, **p < 0.01, ***p < 0.001; Kruskal Wallis test with Bonferroni correction. Data from two independent experiments.

Social behavior in adult zebrafish waterborne exposed to 40 mg/L methamphetamine (METH) for 3 and 48 h. (A) Shoaling test results, including the average and the farthest interfish distances. (B) Social preference test results, including time and distance of the fish in each of the three virtual zones of the experimental tank: empty, center and conspecific. Data from each experiment were normalized to the corresponding control values. The combined data is reported as scatter plot with the median (n = 18 for shoaling test and n = 17–20 for social preference test), *p < 0.05, **p < 0.01, ***p < 0.001; one-way ANOVA with Dunnett’s multiple comparison test (Social Preference Test data) or Kruskal Wallis test with Bonferroni correction (Shoaling test data). Data from two independent experiments.

Significant decrease in the monoaminergic neurotransmitters and other neurochemicals in the brain of zebrafish waterborne exposed to 40 mg/L methamphetamine for 3 and 48 h. In each experiment, levels of each neurochemical were normalized to the corresponding control values. For each neurochemical, the combined data is reported as scatter plot with the median (n = 7–8 for 3 h exposure and n = 15–16 for 48 h exposure), *p < 0.05, **p < 0.01, ***p < 0.001; one-way ANOVA with Dunnett’s multiple comparison test (dopamine, norepinephrine, serotonin) or Kruskal Wallis test with Bonferroni correction (DOPAC, 3-MT, HVA). Data from two independent experiments.

Time-course of the expression of genes involved in the synthesis and transport of catecholamines and neuroinflammation in zebrafish brain after waterborne exposure to 40 mg/l methamphetamine. (A) Expression of th1 and slc18a2, but nor slc6a3 exhibits an early response to methamphetamine. (B) Expression of th2, dbh and gfap exhibits a late response. Data reported as scatter plot with the median. *p < 0.05, **p < 0.01; one-way ANOVA with Dunnett’s multiple comparison test (th1, th2, dbh, slc18a2) or Kruskal Wallis test with Bonferroni correction (slc6a3, gfap). Data from two to three independent experiments (n = 8–16 for th1, th2 and gfap and n = 8 for slc18a2, dbh and slc6a3).