Author(s): HAYASHI, N., TOMIGA, Y., KUSANO, M., MIYAMOTO, S., HASHIMOTO, S., ITO, A., HIGAKI, Y., Institution: FUKUOKA UNIVERSITY, Country: JAPAN, Abstract-ID: 809

INTRODUCTION:
Exercise is known to have beneficial effects on mood disorders, including anxiety and depression. These effects are partly mediated by hippocampal brain-derived neurotrophic factor (BDNF), a key molecule underlying exercise-induced anxiolytic effects. Recent studies have suggested that exercise during pregnancy reduces postpartum depression. However, its effects on affective behavior during pregnancy remain unclear. Therefore, this study aimed to examine the effects of exercise during pregnancy on maternal hippocampal BDNF expression and anxiety-like behaviors.
METHODS:
Female C57BL/6J mice were divided into four groups: non-pregnant/sedentary (NPSed), non-pregnant/exercise (NPEx), pregnant/sedentary (PSed), and pregnant/exercise (PEx). Breeding was conducted using harems. After three days of breeding, the mice were individually reared in cages with or without a voluntary running wheel, and only the Ex group was allowed free access to the wheel. On gestational day 12, anxiety-like behaviors were measured using the elevated plus maze (EPM) test, and the number of open, closed, and total (open + closed) arm entries were analyzed. Dams were euthanized on gestational day 13.5, and the hippocampi were collected. Western blotting analysis was performed to determine hippocampal BDNF protein levels.
RESULTS:
Pregnancy, but not exercise, increased body weight and daily food intake (main effect of pregnancy, p < 0.05). The running distance was lower in the PEx group than that in the NPEx group (p < 0.05). In the EPM test, there were no differences in total arm entries among the groups, suggesting that neither pregnancy nor exercise altered locomotor activity. While the number and percentage of open arm entries relative to the total arm entries were comparable among the groups, closed arm entries decreased with exercise (main effect of exercise, p<0.05). These results suggest that exercise training during pregnancy partially reduces anxiety-like behaviors. Consistent with these results, hippocampal BDNF protein expression levels were increased by exercise (main effect of exercise, p<0.05) but did not change during pregnancy.
CONCLUSION:
We found that exercise training increased hippocampal BDNF protein expression and partially attenuated anxiety-like behaviors during pregnancy. During pregnancy, it is well known that estrogen levels are four times higher than those in non-pregnant animals. A previous study demonstrated the combined effects of estrogen and exercise on hippocampal BDNF expression in ovariectomized female rodents. Our data indicated that pregnancy-associated high estrogen levels did not alter exercise-induced increases in BDNF protein expression. Further studies are required to clarify the underlying mechanisms through which exercise during pregnancy regulates hippocampal BDNF expression and maternal mental health.