Activity measures in rhesus monkeys on long-term calorie restriction

Area of Science:

• Gerontology
• Primate Behavior
• Nutritional Science

Background:

• Calorie restriction (CR) is known to extend lifespan and increase activity in various species.
• Rodent studies consistently show enhanced motor activity under CR diets.
• The effects of CR on behavior in non-human primates remain less understood.

Purpose of the Study:

• To investigate the impact of calorie restriction on behavioral activity in rhesus monkeys.
• To determine if CR-induced activity increases observed in rodents are replicated in primates.
• To assess the effects of CR initiation timing on behavioral outcomes.

Main Methods:

• 19 male rhesus monkeys were divided into control (ad libitum diet) and calorie-restricted (30% less) groups.
• CR was initiated at two different ages: early (2.3 years) and later (4.6 years).
• Behavioral activity was measured using ultrasonic motion detectors and video recording.

Main Results:

• Monkeys initiating CR earlier (Group J) showed higher overall activity and more circling compared to the later-initiated group (Group A).
• Compared to controls, CR monkeys (Group AE) exhibited increased gross motor behavior, pacing, stereotypies, and grooming.
• Activity patterns showed diurnal and circadian rhythms, with peaks around mealtimes.

Conclusions:

• Calorie restriction increases motor activity in rhesus monkeys, mirroring findings in rodent models.
• CR does not inhibit or negatively affect the display of behaviors in rhesus monkeys within a laboratory setting.
• This study provides the first evidence of CR-induced activity increases in a primate model.