The influence of maternal treadmill running during pregnancy on short-term memory and hippocampal cell survival in rat pups.

Maternal exercise during pregnancy has been suggested to exert the beneficial effects on the brain functions of offspring. In the present study, we attempted to determine the effects of maternal treadmill running during pregnancy on short-term memory ability, hippocampal cell survival, and the expression of brain-derived neurotrophic factor (BDNF) mRNA in rat pups. After confirming pregnancy, the pregnant rats were divided into two groups: the control group and the running group (n = 6 in each group). Beginning on the 15th day of pregnancy, the pregnant rats in the running group were forced to run on a treadmill for 30 min at a mild-intensity, once a day until delivery. After all the pregnant rats had given birth, there were rat pups available for use in this study in each group (n = 15 in each group). The latency of the step-down avoidance task was used in order to evaluate the short-term memory ability of the rat pups on the 28 days after birth. Immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU) and reverse transcription-polymerase chain reaction (RT-PCR) for BDNF mRNA were performed to determine hippocampal neurogenesis and hippocampal BDNF mRNA expression of the rat pups on the 29 days after birth, respectively. Our results revealed that maternal running during pregnancy resulted in significant increase in the expression of BDNF mRNA, enhanced hippocampal cell survival, and improved the short-term memory capability of rat pups, as compared to those measured in the control group. The findings of our study provide evidence that maternal running during gestational period may enhance the brain functions of offspring.