The spatial learning and memory performance in methamphetamine–sensitized and withdrawn rats

Objective(s): There is controversial evidence about the effect of methamphetamine (METH) on spatial memory. We tested the time- dependent effects of METH on spatial short-term (working) and long-term (reference) memory in METH –sensitized and withdrawn rats in the Morris water maze. Materials and Methods: Rats were sensitized to METH (۲ mg/kg, daily/۵ days, SC). Rats were trained in water maze (۴ trials/day/ for ۵ days). Probe test was performed ۲۴ hr after training. Two days after probe test, working memory training (۲ trials/day/ for ۵ days) was conducted. Acquisition–retention interval was ۷۵ min. The treatment was continued per day ۳۰ and ۱۲۰ min before the test. Two groups of METH –sensitized rats were trained in reference memory after a longer period of withdrawal (۳۰ days). Results: Sensitized rats exhibited significantly longer escape latencies on the training, spent significantly less time in the target zone (all, P<۰.۰۵), and their working memory impaired ۳۰ min after injection. While, METH has no effect on the spatial learning process ۱۲۰ min after injection, and rats spent significantly less time in the target zone (P<۰.۰۵), as well it has no effect on working memory. Also, impairment of reference memory persisted after prolonged abstinence. Conclusion:Our findings indicated that METH impaired spatial learning and memory ۳۰ min after injection, but spared spatial learning, either acquisition or retention of spatial working, but partially impaired retention of spatial reference memory following ۱۲۰ min after injection in sensitized rats, which persisted even after prolonged abstinence.

کلیدواژه ها:

Long -term memory ، METH- sensitized rats ، Short -term memory ، Spatial Memory