Psycho-social stress is one of the important risk factor for depression. Recent studies demonstrate that intake of comfortable foods eases depressive behavior in social defeat stress-induced depressive (SDS) mice. However, continues feeding of comfortable foods increases volume of food intake and body weight, thereby leading to be obesity. In this study, we determined whether small volume intake of comfortable diet which did not affect body weight was enough for improvement of social behavior in SDS-induced mice.
Male C57BL/6J mice were attacked by retired ICR mice for 2.5 min every day. One group was given high fat diet (HFD) as a comfortable food for 2 hours; another group was given HFD ad libitum. Eleven days later, we performed behavioral tests and checked the effect of HFD on psychological behavior in SDS mice.
Compared to non-stressed control group, SDS mice showed negative social interaction with retired ICR mice. Ad libitum intake of HFD improved this negative social behavior with increase of body weight whereas restricted HFD intake showed similar improvement of social interaction without change of body weight. There was no difference on weight of white adipose tissue between restricted HFD group and control group. SDS mice showed higher plasma corticosterone concentration and adrenal gland weight than those of control group. While HFD intake decreased adrenal gland weight, plasma corticosterone level did not decrease. These results suggest a possibility that HFD has a role for the regulation of psychological behavior with no involvement in glucocorticoid.
In conclusion, restricted HFD intake may improve psychological behavior such as social interaction without change of body weight and composition in SDS mice.