Feeding and drinking patterns of ovariectomized old female rats.

Circadian rhythms and patterns of feeding and drinking behavior of ovariectomized old female rats (23 to 34 months of age) were studied and the changes due to the aging process were analyzed. In order to assess sex difference in these patterns in old age, the data were also compared with the previous studies in old male rats. There was significant increase in daily feeding events but not in licking events in old female rats. Circadian rhythms disappeared in 2 out of 7 old female rats in feeding events and 1 out of 8 old female rats in licking events. The remaining old rats which still showed circadian rhythmicity in feeding events and licking events, had smaller meal number/day, larger mean intermeal interval, quicker feeding events/min/meal, larger draft number/day, shorter mean draft duration, longer mean interdraft interval and quicker licking events/min/draft than young female rats. Drinking/feeding ratio was higher in the dark period than the light period in young as well as old female rats. These changes resemble those in old male rats and in ventromedial hypothalamic lesioned rats in the obese stage, but to less extent.