New Perspectives on Avian Models for Studies of Basic Aging Processes

Abstract

Avian models have the potential to elucidate basic cellular and molecular mechanisms underlying the slow aging rates and exceptional longevity typical of this group of vertebrates. To date, most studies of avian aging have focused on relatively few of the phenomena now thought to be intrinsic to the aging process, but primarily on responses to oxidative stress and telomere dynamics. But a variety of whole-animal and cell-based approaches to avian aging and stress resistance have been developed—especially the use of primary cell lines and isolated erythrocytes—which permit other processes to be investigated. In this review, we highlight newer studies using these approaches. We also discuss recent research on age-related changes in neural function in birds in the context of sensory changes relevant to homing and navigation, as well as the maintenance of song. More recently, with the advent of “-omic” methodologies, including whole-genome studies, new approaches have gained momentum for investigating the mechanistic basis of aging in birds. Overall, current research suggests that birds exhibit an enhanced resistance to the detrimental effects of oxidative damage and maintain higher than expected levels of cellular function as they age. There is also evidence that genetic signatures associated with cellular defenses, as well as metabolic and immune function, are enhanced in birds but data are still lacking relative to that available from more conventional model organisms. We are optimistic that continued development of avian models in geroscience, especially under controlled laboratory conditions, will provide novel insights into the exceptional longevity of this animal taxon.

Do Antioxidants Extend Longevity in Invertebrate and Vertebrate Animals?

“…However, fishes are exotherms, just as invertebrates are, but mice (i.e., mammals) are endotherms. So too are birds, which also fail to show a consistent effect of oxidative stress and/or antioxidant capacity on the aging process [119]. Taken together, this suggests that the relevance of oxidative stress as a potential modulator of the aging process in humans is minimal, although it certainly is involved in numerous pathophysiological processes.…”

Declining haematocrit with increasing age in a population of male zebra finchesTaeniopygia guttata

“…Studying animals in the wild, particularly regarding ageing, however, has many potential pitfalls, due in part to animals experiencing episodic variation in food, temperature and moisture extremes, predation or disappearance for other reasons such as dispersal (Harper and Holmes 2021). Coupled with the fact that birds have natural variation in Hct, as well as all other HVs, caused by many variables including age, reproductive status, geographical elevation, season, parasitism and nutritional status, it is difficult to attribute any single parameter to a change in the Hct unless these other variables can be controlled for in a stable environment (Fair et al 2007).…”

The effect of age on delay performance and associative learning tasks in pigeons

“…Similar age-related performance decrements and neural changes are found in nonhuman primates (Puig & Miller, 2012;Wang et al, 2011) and rats (Bizon et al, 2009;Smith et al, 2022), but it is unclear if these are universal properties of aging or are restricted to mammals. Birds are a more recent model of aging that provide a useful outgroup against which to compare mammalian studies (Coppola et al, 2015;Coppola et al, 2016;Harper & Holmes, 2021;Kosarussavadi et al, 2017;Meier et al, 2021). Many avian species have longer life spans than expected compared with mammals of similar body mass (Holmes et al, 2001).…”

“…This is particularly surprising since birds have increased physiological demands, such as higher body temperature, higher blood glucose level, and higher metabolic rate (Holmes et al, 2001). Because of these physiological differences, birds have been used to investigate various biochemical theories of aging at the cellular level (Harper & Holmes, 2021;Holmes et al, 2001). Even though birds have been used to investigate potential protective mechanisms against senescence at the cellular level, relatively little is known about how cognitive performance and the avian brain changes with age, despite being investigated for over 100 years (Coppola et al, 2015;Coppola et al, 2016;Harper & Holmes, 2021;Jarvis et al, 2005;Meier et al, 2021).…”

“…Because of these physiological differences, birds have been used to investigate various biochemical theories of aging at the cellular level (Harper & Holmes, 2021;Holmes et al, 2001). Even though birds have been used to investigate potential protective mechanisms against senescence at the cellular level, relatively little is known about how cognitive performance and the avian brain changes with age, despite being investigated for over 100 years (Coppola et al, 2015;Coppola et al, 2016;Harper & Holmes, 2021;Jarvis et al, 2005;Meier et al, 2021). Cognitive neuroscience experiments with pigeons and corvids frequently show that these birds perform similarly to primates on cognitive tasks (Güntürkün et al, 2017).…”