Control of food intake and meal patterns in monkeys.

Control of food intake and meal patterns in monkeys. PHYSIOL. BEHAV. 27(5) 803-810, 1981.-Feeding patterns have been studied in 10 adult male rhesus monkeys (Macaca mulatta) adapted to primate restraint chairs for physiological studies. Using an automated computer-monitored liquid diet feeding system, feeding behavior was studied under 8 hour and 24 hour feeding schedules. Caiorie/kg intake was significantly reduced with the 8 hour schedule (0<0.05). Average rate of weight gain and feeding efficiency were also lower with 8 hour feeding, but not significantly different from 24 hour ad lib feeding (0>0.10). Meal size was negatively correlated with meal frequency across monkeys, but not within monkeys. Although monkeys ingested 78% of their voluntary intake during the light hours, there was no difference in meal size, meal duration, or rate of feeding between light and dark periods. With feeding restricted to 8 hours during the light period, meal size was positively correlated with the length of the interval preceding the meal in 4 of 6 monkeys, and meal size was also positively correlated with length of the postmeal interval in 3 of 6 monkeys. In contrast, 24 hour ad lib fed monkeys showed no relationship between premeal interval and subsequent meal size, but a positive correlation between meal size and postmeal interval in 3 of 4 monkeys. We conclude that feeding schedule or deprivation state may alter the relative roles of "hunger" and "satiety" signals in regulating food intake amounts and patterns. Macaca mulatta Feeding pattern Intermeal interval Meal frequency Meal size Meal duration Hunger Satiety INVESTIGATIONS of the physiology underlying the regulation of feeding behavior depend significantly upon the ability to define and characterize spontaneous patterns of intake under specified nutritional conditions. Studies of feeding regulation have been carried out primarily in may provide data important to understanding human feeding behavior. We now present an analysis of feeding patterns and caloric intakes of adult rhesus monkeys, in a model developed specifically to permit sensitive and detailed simultaneous assessment of the multiple behavioral and physiological parameters involved in the regulation of food intake. Results support the use of monkeys in studies of the physiological controls of feeding, and emphasize the importance of within animal comparisons when seeking to demonstrate effects on feeding behavior. METHOD Subjects The feeding behavior of 10 male rhesus monkeys fMacaca mulatta) was studied under chair-restrained conditions prior to or between experiments requiring chronic intravenous catheterization. Six monkeys were …