Abstract
Anticipation of daily recurring changes in the environment is critical for survival. When food access is limited to a few hours during the daytime, nocturnal rodents exhibit food-anticipatory activity, which appears a few hours before scheduled mealtime. The rodents are also known to exhibit anticipatory activity for time-restricted palatable meals under ad libitum access to chow. When 1 h of chocolate chip access was given during the day, mice exhibited robust anticipatory activity. In contrast, despite the peanut butter-fed mice eating two times the calories of peanut butter than the chocolate-fed mice did of chocolate chips, we observed only negligible anticipatory activity for daily 1-h peanut butter administration. In ex vivo explants, the phase of the liver in mice subjected to timed-chocolate chip access was significantly advanced, similarly to that in mice subjected to 4-h restricted feeding during the day. Similar to anticipatory activity, negligible phase changes in the liver were observed in the mice given 1 h of peanut butter access during the day. Therefore, robustness of palatable meal-anticipatory activity and phase advance in the liver are unlikely to be in direct response to increased calorie intake during the day. We measured food-seeking nose-poking behavior during food deprivation following daily 1-h chocolate chip access. Mice expressed anticipatory food seeking around the time that they had previously been given daily chocolate chips. This suggests that the time of chocolate chip access is encoded to the same circadian pacemaker that controls food-anticipatory activity.NEW & NOTEWORTHY Anticipatory activity for daily chocolate chip access is stronger than that for daily peanut butter access. Mice given daily chocolate chip access, but not peanut butter access, exhibited altered circadian organization among peripheral clocks. During food deprivation, mice exhibited anticipatory food-seeking behavior at the time they had previously been given chocolate chip access, suggesting that the time of palatable meals is encoded in the circadian pacemaker controlling food-anticipatory activity.