Take the monkey and run

Abstract

Background: The common marmoset (Callithrix jacchus) is a small, New World primate that is used extensively in biomedical and behavioral research. This short-lived primate, with its small body size, ease of handling, and docile temperament, has emerged as a valuable model for aging and neurodegenerative research. A growing body of research has indicated exercise, aerobic exercise especially, imparts beneficial effects to normal aging. Understanding the mechanisms underlying these positive effects of exercise, and the degree to which exercise has neurotherapeutic effects, is an important research focus. Thus, developing techniques to engage marmosets in aerobic exercise would have great advantages.

New method: Here we describe the marmoset exercise ball (MEB) paradigm: a safe (for both experimenter and subjects), novel and effective means to engage marmosets in aerobic exercise. We trained young adult male marmosets to run on treadmills for 30 min a day, 3 days a week.

Results: Our training procedures allowed us to engage male marmosets in this aerobic exercise within 4 weeks, and subjects maintained this frequency of exercise for 3 months.

Comparison with existing methods: To our knowledge, this is the first described method to engage marmosets in aerobic exercise. A major advantage of this exercise paradigm is that while it was technically forced exercise, it did not appear to induce stress in the marmosets.

Conclusions: These techniques should be useful to researchers wishing to address physiological responses of exercise in a marmoset model.

Keywords: Aging research; Exercise; Marmoset (Callithrix jacchus); Primate models.

Fig. 1

(a) A marmoset securely contained in the clear plastic capture container. (b) A marmoset in the exercise ball, ready to engage in treadmill running. The backs of subjects were shaved in order to facilitate viewing of the identification tattoo.

Fig. 2

Illustration of the rectangular frame, constructed of PVC, that was secured to the treadmill to secure the exercise ball on the treadmill during operation. Illustration by M. Karen Hambright.

Fig. 3

Still image of marmoset in exercise ball on treadmill. On the online version this is an approximate 90s video showing a marmoset running on the treadmill

Fig. 4

Mean weights of marmosets throughout the acclimation (weeks 1–4) and exercise (weeks 5–16) sessions. While subjects in the exercise group had a higher mean weight throughout the study than the marmosets that did not continue to exercise after the acclimation period, individual weights in that group also showed a large range (303–578 g).