Characteristics of effects of repeated scopolamine administration on ambulatory activity in mice and methamphetamine sensitivity in the scopolamine-experienced mice: comparison among 6 strains.
Effects of scopolamine (0.5 mg/kg, s.c.) on ambulatory activity were investigated in 6 strains of mice (dd, ICR, BALB, C57BL, C3H and DBA). Scopolamine increased ambulatory activity, and the sensitivities were in the order of ICR greater than C3H greater than BALB greater than DBA greater than C57BL greater than dd. This was different from that produced by methamphetamine (2 mg/kg, s.c.) where the order was ICR greater than dd greater than DBA greater than C3H greater than C57BL greater than BALB. A tolerance to the ambulation-increasing effect of scopolamine was progressively produced in dd, ICR, C57BL and DBA strains, but not in BALB and C3H strains, when the drug was administered 5 times at intervals of 3-4 days. The repeated scopolamine treatment elicited a major enhancement of the sensitivity to the ambulation-increasing effect of methamphetamine (2 mg/kg, s.c.) in BALB and C3H strains and a minor enhancement in the C57BL strain, whereas dd, ICR and DBA strains did not exhibit a marked change in the sensitivity to methamphetamine even after the same treatment with scopolamine. These results suggest that the ambulation-increasing effect of scopolamine is different from that of methamphetamine and that the interaction between scopolamine and methamphetamine varies among different strains of mice.
Division for Behavior Analysis, Gunma University School of Medicine, Maebashi, Japan.
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Kuribara
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Tadokoro
D000818:Animals; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000187:drug effects*; D012601:Scopolamine / Q000494:pharmacology*; D013045:Species Specificity
D008694:Methamphetamine; D012601:Scopolamine