Zebrafish (Danio rerio) as a model for the study of aging and exercise: Physical ability and trainability decrease with age

Abstract

A rapidly aging global population has motivated the development and use of models for human aging. Studies on aging have shown parallels between zebrafish and humans at the internal organization level; however, few parallels have been studied at the whole-organism level. Furthermore, the effectiveness of exercise as a method to mitigate the effects of aging has not been studied in zebrafish. We investigated the effects of aging and intermittent exercise on swimming performance, kinematics and behavior. Young, middle-aged and old zebrafish (20-29, 36-48 and 60-71% of average lifespan, respectively) were exercised to exhaustion in endurance and sprint swimming tests once a week for four weeks. Both endurance and sprint performance decreased with increased age. Swimming performance improved with exercise training in young and middle-aged zebrafish, but not in old zebrafish. Tail-beat amplitude, which is akin to stride length in humans, increased for all age groups with training. Zebrafish turning frequency, which is an indicator of routine activity, decreased with age but showed no change with exercise. In sum, our results show that zebrafish exhibit a decline in whole-organism performance and trainability with age. These findings closely resemble the senescence-related declines in physical ability experienced by humans and mammalian aging models and therefore support the use of zebrafish as a model for human exercise and aging.

Macro- and microstructural descriptions of the zebrafish (Danio rerio) liver

“…The population density was 3 fish per litre. The experiment lasted 13 weeks so that fish age at the end of the experiment was between 16 and 22 months (adults) corresponding to approximately 48% of the average life expectancy in the laboratory [3].…”

Evidence of an Association between Age-Related Functional Modifications and Pathophysiological Changes in Zebrafish Heart

“…Our study examining critical swimming speed and evaluating exercise tolerance showed that critical swimming speed decreased significantly and exercise tolerance declined with aging in zebrafish. A recent study of zebrafish by Gilbert et al [5] has reported that not only swimming speed and endurance but also the ability of exercise training to improve performance decreased with age. The swimming challenge test in fish is similar to the treadmill test in humans in that it describes exercise capacity and endurance.…”

“…Its short life span, transparent embryo, gradual physiological aging, and amenability to genetic engineering have caused it to be used for many development and disease studies. Like humans, aged zebrafish have reduced exercise tolerance [5], degenerative changes in the spinal column [6], and cognitive decline [7,8]. And like humans, differences in genetics have been shown to contribute to differences in life span [9].…”

Age-Related Changes in Locomotor Performance Reveal a Similar Pattern forCaenorhabditis elegans,Mus domesticus,Canis familiaris,Equus caballus, andHomo sapiens

“…Based on these results, we hypothesize that these age-related patterns are common features of the relationship between age and locomotor performance in a wide range of organisms. The shape of the patterns seems to match descriptions of other age-related locomotor performances in different species, such as flight performances in Drosophila (31), honeybees (32), and codling moths (33), maximal sprint speed in dogs and horses (34)(35)(36), physical activity in different rodents and monkeys (16,27,28), grip strength in mouse lemurs (15), hunting rates and success in wolves (37), swimming speed in zebrafish (38), and voluntary activity and electrotactic behavior in C. elegans (29,39). Likewise, other performance traits might follow a similar pattern, such as biting force in mouse lemur (40), cognitive performances in Rhesus monkey (41), attentiveness in domestic dogs (42), pharynx pumping rate in C. elegans (43), and perhaps even photosynthetic yield in cotton leaves (44).…”