Treadmill exercise alleviates short-term memory impairments of pups born to old and obese mother rats.

Obesity causes atrophy of the brain, leading to deterioration in working memory, learning, and cognitive function. The status of short-term memory in rat pups born to older obese mother rats was verified, and the effect of treadmill exercise on short-term memory in rat pups was investigated. Step-down avoidance test for short-term memory, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining for apoptosis, and immunohistochemistry for Ki67 for new cell generation were done. The old female rats were fed with normal diet (5% of fat), and the old and obese female rats were fed with high-fat diet (60% of fat) for up to 50 weeks in age (for 44 weeks in experimental period). The newborn rats were divided into four groups according to the conditions of the mother rats as follows: the rat pups group born to old rats, the rat pups group born to old rats with exercise, the rat pups group born to old and obese rats, the rat pups group born to old and obese rats with exercise. Maternal exercise improved short-term memory, decreased TUNEL-positive cell number, and increased Ki67-positive cell number of the pups born to old and obese rats. Maternal exercise has been found to contribute to eliminating the health risks of fetuses born to old obese mothers.