Table 5

Effects of methamphetamine on striatal t-MeHA levels and locomotor activity

Treatment PeriodWithdrawal Period
Day 1Day 5Day 8Day 17
ControlsSensitizedControlsSensitizedControlsSensitized
Basal t-MeHA levels (ng/g)110  ± 597  ± 4132  ± 115-153 124  ± 7138  ± 18101  ± 6145  ± 85-162
Enhancement of t-MeHA levels
 ED50 (mg/kg)0.7  ± 0.30.6  ± 0.30.7  ± 0.31.1  ± 0.62.1  ± 0.60.6  ± 0.31.6  ± 0.5
 E max(percentage of control)252  ± 18249  ± 18225  ± 16234  ± 27248  ± 18251  ± 21231  ± 17
Locomotor activity (photocell counts/90 min)
 MET 2 mg/kg i.p.2390  ± 3124472  ± 4935-150 6177  ± 12835-150 5626  ± 1725-160
 MET 0.5 mg/kg i.p.1158  ± 3923529  ± 5495-160

Mice received methamphetamine (2 mg/kg b.i.d.) (sensitized) or saline (controls) for 5 days. At the end of the treatment (day 5) and after either a 2-day or an 11-day interruption (days 8 and 17, respectively), changes in t-MeHA levels were evaluated 3 h following the administration of saline (basal levels) or methamphetamine in increasing dosages. Values were derived from the dose-response curves. The maximal responses, i.e., corresponding to striatal levels of 260 ± 14, 247 ± 23, 290 ± 33, and 290 ± 33 ng/g for days 1, 5, 8, and 17, respectively, were not significantly modified in sensitized mice.

  • ↵5-150  p < 0.05;

  • ↵5-160  p < 0.01 compared with a single injection (day 1).

  • ↵5-153  p < 0.05;

  • ↵5-162  p < 0.001 vs. respective controls in Mann-Whitney test.