Neuroendocrine and immune characteristics of aging in avian species

Abstract

Avian species show a remarkable diversity in lifespan. The differing lifespan patterns are found across a number of birds, in spite of higher body temperature and apparent increased metabolic rate. These characteristics make study of age-related changes of great interest, especially for understanding the biology of aging associated with surprisingly long lifespan in some birds. Our studies have focused on a short-lived avian model, the Japanese quail in order to describe reproductive aging and the neuroendocrine characteristics leading to reproductive senescence. Biomarkers of aging used in mammalian species include telomere length, oxidative damage, and selected metabolic indicators. These markers provide confirming evidence that the long-lived birds appear to age more slowly. A corollary area of interest is that of immune function and aging. Immune responses have been studied in selected wild birds and there has been a range of studies that have considered the effects of stress in wild and domestic species. Our laboratory studies have specifically tested response to immune challenge relative to aging in the quail model and these studies indicate that there is an age-related change in the qualitative aspects of the response. However, there are also intriguing differences in the ability of the aging quail to respond that differ from mammalian data. Finally, another approach to understanding aging is to attempt to develop or test strategies that may extend lifespan and presumably health. One area of great interest has been to consider the effect of calorie restriction, which is a treatment shown to extend lifespan in a variety of species. This approach is routinely used in domestic poultry as a means for extending reproductive function and enhancing health. Our data indicate that moderate calorie restriction has beneficial effects, and that physiological and endocrine responses reflect these benefits.

Insights into Biomedicine from Animal Adaptations

“…The brain content of GnRH decreases in both males and females with senescence; interestingly in senescent males, the decrease in GnRH is seen in both the POA and ME, while in senescent females the decline is seen in the ME but not the POA. These findings are consistent with the observation that neuronal cell number changes little with aging in females but in males, cell number decreases with aging (81). In addition, the observations of Dellovade et al (31) indicate that individual male quail reproductively age at different rates and that this rate reflects the aging of the underlying neuroendocrine system that regulates reproductive behaviors.…”

Dynamic spleen mass in wild and domestic American mink

“…We have concluded that differences in spleen mass between wild and domestic mink, and between feral domestic mink and domestic mink on farms are the result of differences in the prevalence and abundance of parasites and pathogens. Nonetheless, spleen size can be affected by other factors, including age (Ottinger & Lavoie, ; Cowan et al ., ), stress (McEwan et al ., ), and season (Silverin et al ., ). We argue that age is unlikely to be a factor because even if wild and domestic mink vary in age, age differences are unlikely to explain differences in spleen mass between domestic and feral mink, given that feral mink had escaped from mink farms.…”

Integrating Environment and Aging Research: Opportunities for Synergy and Acceleration

“…These adaptations are also observed in non-mammalian species, with comparison of short- and long-lived species such as in birds ( Ogburn et al, 2001 ). Furthermore, short-lived species show many age-related declines in neural and endocrine systems and increased incidence of cancer ( Gorham and Ottinger, 1986 ; Ottinger et al, 2004 ; Ottinger and Lavoie, 2007 ; Ottinger, 2007 ; Johnson and Giles, 2013 ). As such, these comparative studies offer significant insights into conserved mechanisms occurring throughout vertebrates during the aging process ( National Academy of Sciences, 2014 ; Niedernhofer et al, 2017 ).…”