Social confrontation stress decreases hepatic fibroblast growth factor-21 expression in aged mice.

We previously showed that social stress exposure in mature adult mice increased blood corticosterone concentrations at 2 days, disrupted hepatic lipid metabolism-related pathway at 30 days, and increased the risk of overweight with hepatic hypertrophy at 90 days. To further investigate the effects of aging on the physiological responses to social stress, we conducted a study using male BALB/c mice at the ages of 2 months (mature age), 14 months (middle age) and 26 months (old age), and exposed them to confrontation stress for 2 or 7 days. Blood corticosterone concentrations were increased at 2 days of stress, and then returned to baseline concentrations. This change was observed only at 2 months of age. We further examined the effect of aging on hepatic gene expression of fibroblast growth factor-21 () and found that its expression was significantly decreased after 7 days of stress at 14 months of age and after 2 days of stress at 26 months of age, indicating these decreasing effects became more pronounced with age. In conclusion, our study suggests that hepatic expression decrease under exposure to confrontation stress at middle or more age, indicating that stress response on related pathway might be more pronounced with age when exposed to stress.