Effect of swimming exercise on spatial learning and memory, and voluntary morphine consumption in maternally separated rats in adulthood

Maternal separation (MS) can lead to learning and memory deficits, and also the risk of addiction. On the other hand, physical activities may lead to long-term changes in the mesolimbic dopamine pathway and the hippocampus. This study was designed to examine the effect of swimming exercise on the spatial learning and memory and voluntary morphine consumption in maternally separated male and female rats.

Rat pups were separated daily from their mothers for 3h during postnatal days 2–15. All pups were weaned on day 21. The exercising rats were exposed to swimming exercise for 1 hour per day during postnatal days 28–57. At the end of this period, rats were tested for the spatial learning and memory in the Morris Water Maze, and voluntary morphine consumption using a two‐bottle choice paradigm.

We found that the MS male and female pups showed longer escape latencies to find the platform as training progressed than No MS/no swim rats. Also, swimming exercise shortened the latency to escape in the male and female MS pups than MS/no swim pups. MS and swimming had no effect on spatial memory in the probe test. Also, voluntary morphine consumption was higher in the male and female MS/no swim than No MS/no swim pups, while swimming exercise decreased it.

Our results have shown that swimming exercise during adolescence may be of benefit for prevention of drug abuse and recovery from cognitive deficits following neonatal MS.