The Feeding Pattern of C57BL/6J Mice

The feeding pattern and control of energy intake in social mice are poorly understood. Here, we determined and quantify the normal nocturnal feeding pattern of group-housed male and female mice of the C57BL/6J genetic background fed a chow diet. Mice at 10 and 20weeks of age showed the expected age-dependent increase in lean and fat mass being them more pronounced in males. Under ad libitum conditions, male and female mice ate comparable amounts of food per unit of body weight irrespective of gender. The analysis of the feeding microstructure revealed that energy intake in females is the result of significantly increased nocturnal meal size, but decreased meal frequency, relative to males suggesting that food has reduced satiation value to social females than to males. The intermeal interval was significantly increased in female mice relative to males, but only at 10weeks of age, indicating increased satiety value of food in younger females. The increased meal size observed in females was accompanied by increased meal duration, which translated to significant reduction in the feeding rate of younger females but not in older mice fed ad libitum. In response to prolonged fasting, male and female mice lost comparable body mass, but females recovered it faster than males in spite of eating equivalent amount of food as males. Further, younger but not older female mice fasted 16hs robustly increased their meal size during the first hours of re-feeding whereas males did not, suggesting reduced inhibition of satiation in fasted young female mice relative to males. Both, fasted males and female mice significantly reduced their intermeal interval during the first hours of re-feeding to similar extents independently of their age suggesting that fasting inhibits satiety in mice. Therefore, when taken together these results demonstrate that satiation and satiety signals governing energy intake in mice are sex- and age-dependent