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Wilkinson GS, Adams DM, Rayner JG. Sex, season, age and status influence urinary steroid hormone profiles in an extremely polygynous neotropical bat. Horm Behav 2024; 164:105606. [PMID: 39059233 PMCID: PMC11330717 DOI: 10.1016/j.yhbeh.2024.105606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 06/17/2024] [Accepted: 07/16/2024] [Indexed: 07/28/2024]
Abstract
Several polygynous mammals exhibit reproductive skew in which only a few males reproduce. Successful males need strength, stamina and fighting ability to exclude competitors. Consequently, during the mating season their androgens and glucocorticoids are expected to increase to support spermatogenesis and aggressive behavior. But, during the nonmating season these hormones should decline to minimize deleterious effects, such as reduced immune function. Bats that exhibit harem polygyny in which males aggressively defend large groups of females year-round are ideal for assessing hormonal and other consequences of extreme polygyny. Here we use DNA methylation to estimate age and gas chromatography, tandem mass spectrometry to profile steroid metabolites in urine of wild greater spear-nosed bats, Phyllostomus hastatus, across seasons. We find that condition, measured by relative weight, is lower during the mating season for both sexes, although it remains high in harem males during the mating season. Average age of females is greater than males, and females exhibit substantial seasonal differences in androgens, estrogens and glucocorticoids with higher levels of all hormones during the mating season. Males, however, show little seasonal differences but substantial age-associated increases in most steroid metabolites. Harem males have larger, persistently scrotal testes and are older than bachelor males. While cortisone generally declines with age, harem males maintain higher amounts of biologically active cortisol than bachelor males all year and cortisol levels increase more quickly in response to restraint in males than in females. Taken together, these results suggest that attaining reproductive dominance requires hormone levels that reduce lifespan.
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Affiliation(s)
| | - Danielle M Adams
- Department of Biology, University of Maryland, College Park, MD 20742
| | - Jack G Rayner
- Department of Biology, University of Maryland, College Park, MD 20742
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2
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Alonge MM, Greville LJS, Ma X, Faure PA, Bentley GE. Acute restraint stress rapidly impacts reproductive neuroendocrinology and downstream gonad function in big brown bats (Eptesicus fuscus). J Exp Biol 2023; 226:jeb245592. [PMID: 37827114 PMCID: PMC10629485 DOI: 10.1242/jeb.245592] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 08/23/2023] [Indexed: 10/14/2023]
Abstract
Animals face unpredictable challenges that require rapid, facultative physiological reactions to support survival but may compromise reproduction. Bats have a long-standing reputation for being highly sensitive to stressors, with sensitivity and resilience varying both within and among species, yet little is known about how stress affects the signaling that regulates reproductive physiology. Here, we provide the first description of the molecular response of the hypothalamic-pituitary-gonadal (HPG) axis of male big brown bats (Eptesicus fuscus) in response to short-term stress using a standardized restraint manipulation. This acute stressor was sufficient to upregulate plasma corticosterone and resulted in a rapid decrease in circulating testosterone. While we did not find differences in the mRNA expression of key steroidogenic enzymes (StAR, aromatase, 5-alpha reductase), seminiferous tubule diameter was reduced in stressed bats coupled with a 5-fold increase in glucocorticoid receptor (GR) mRNA expression in the testes. These changes, in part, may be mediated by RFamide-related peptide (RFRP) because fewer immunoreactive cell bodies were detected in the brains of stressed bats compared with controls - suggesting a possible increase in secretion - and increased RFRP expression locally in the gonads. The rapid sensitivity of the bat testes to stress may be connected to deleterious impacts on tissue health and function as supported by significant transcriptional upregulation of key pro-apoptotic signaling molecules (Bax, cytochrome c). Experiments like this broadly contribute to our understanding of the stronger ecological predictions regarding physiological responses of bats within the context of stress, which may impact decisions surrounding animal handling and conservation approaches.
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Affiliation(s)
- Mattina M. Alonge
- University of California, Berkeley, Department of Integrative Biology, Berkeley, CA 94720-3200, USA
| | - Lucas J. S. Greville
- McMaster University, Department of Psychology, Neuroscience & Behaviour, Hamilton, ON, Canada, L8S 4L8
- University of Waterloo, Department of Biology, Waterloo, ON, Canada, N2L 3G1
| | - Xuehao Ma
- University of California, Berkeley, Department of Integrative Biology, Berkeley, CA 94720-3200, USA
- Helen Wills Neuroscience Institute, Berkeley, CA 94720, USA
| | - Paul A. Faure
- McMaster University, Department of Psychology, Neuroscience & Behaviour, Hamilton, ON, Canada, L8S 4L8
| | - George E. Bentley
- University of California, Berkeley, Department of Integrative Biology, Berkeley, CA 94720-3200, USA
- Helen Wills Neuroscience Institute, Berkeley, CA 94720, USA
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3
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Edwards MJ, Stanley CR, Hosie CA, Richdon S, Price E, Wormell D, Smith TE. Social roles influence cortisol levels in captive Livingstone's fruit bats (Pteropus livingstonii). Horm Behav 2022; 144:105228. [PMID: 35772196 DOI: 10.1016/j.yhbeh.2022.105228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/03/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022]
Abstract
A critical component of conserving and housing species ex situ is an explicit scientific understanding of the physiological underpinnings of their welfare. Cortisol has been repeatedly linked to stress, and therefore used as an indicator of welfare for many species. In order to measure cortisol in the Livingstone's fruit bat (Pteropus livingstonii; a critically endangered keystone species) without disturbing the captive population, we have developed and validated a non-invasive, novel hormone extraction procedure and faecal glucocorticoid assay. A total of 92 faecal samples, 73 from the P. livingstonii breeding colony at Jersey Zoo, Channel Islands and 19 samples from P. livingstonii housed at Bristol Zoological Gardens, UK, have been collected and analyzed. Mixed-effect modelling of the influence of physiological state variables on cortisol concentration revealed that lactating females had higher cortisol levels than non-lactating females, indicating that our assay is measuring biologically relevant hormone concentrations. Males and older bats also had higher cortisol than non-lactating females and younger individuals. Further analysis applied social network methodology to compare the cortisol levels of bats with different social roles. We found that individuals that linked social groups possessed higher than average cortisol levels and conversely, individuals with high-quality, positive relationships had lower cortisol levels. These results demonstrate, for the first time in a bat species, social mediation of stress hormones. Lastly, the frequency of vocalisation was found to positively correlate with cortisol concentration in males, suggesting that this behaviour may be used by animal management as a visual indicator of a bat's hormonal status. Hence, this research has provided unique insights and empirical scientific knowledge regarding the relationship between the physiology and social behaviour of P. livingstonii, therefore allowing for recommendations to be made to optimise bat welfare at the individual level.
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Affiliation(s)
- Morgan J Edwards
- Animal Behaviour and Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4BJ, UK.
| | - Christina R Stanley
- Animal Behaviour and Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4BJ, UK.
| | - Charlotte A Hosie
- Animal Behaviour and Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4BJ, UK.
| | - Sarah Richdon
- Institute of Conservation Science & Learning, Bristol Zoological Society, Clifton, Bristol BS8 3HA, UK.
| | - Eluned Price
- Durrell Wildlife Conservation Trust, Trinity, Jersey JE3 6AP, UK.
| | - Dominic Wormell
- Durrell Wildlife Conservation Trust, Trinity, Jersey JE3 6AP, UK.
| | - Tessa E Smith
- Animal Behaviour and Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4BJ, UK.
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4
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Mishra I, Knerr RM, Stewart AA, Payette WI, Richter MM, Ashley NT. Light at night disrupts diel patterns of cytokine gene expression and endocrine profiles in zebra finch (Taeniopygia guttata). Sci Rep 2019; 9:15833. [PMID: 31676761 PMCID: PMC6825233 DOI: 10.1038/s41598-019-51791-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 10/08/2019] [Indexed: 11/22/2022] Open
Abstract
Increased exposure to light pollution perturbs physiological processes through misalignment of daily rhythms at the cellular and tissue levels. Effects of artificial light-at-night (ALAN) on diel properties of immunity are currently unknown. We therefore tested the effects of ALAN on diel patterns of cytokine gene expression, as well as key hormones involved with the regulation of immunity, in zebra finches (Taeniopygia guttata). Circulating melatonin and corticosterone, and mRNA expression levels of pro- (IL-1β, IL-6) and anti-inflammatory (IL-10) cytokines were measured at six time points across 24-h day in brain (nidopallium, hippocampus, and hypothalamus) and peripheral tissues (liver, spleen, and fat) of zebra finches exposed to 12 h light:12 h darkness (LD), dim light-at-night (DLAN) or constant bright light (LLbright). Melatonin and corticosterone concentrations were significantly rhythmic under LD, but not under LLbright and DLAN. Genes coding for cytokines showed tissue-specific diurnal rhythms under LD and were lost with exposure to LLbright, except IL-6 in hypothalamus and liver. In comparison to LLbright, effects of DLAN were less adverse with persistence of some diurnal rhythms, albeit with significant waveform alterations. These results underscore the circadian regulation of biosynthesis of immune effectors and imply the susceptibility of daily immune and endocrine patterns to ALAN.
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Affiliation(s)
- Ila Mishra
- Department of Biology, Western Kentucky University, Bowling Green, KY, USA
| | - Reinhard M Knerr
- Department of Biology, Western Kentucky University, Bowling Green, KY, USA
| | | | - Wesley I Payette
- Department of Biology, Western Kentucky University, Bowling Green, KY, USA
| | - Melanie M Richter
- Department of Biology, Western Kentucky University, Bowling Green, KY, USA
| | - Noah T Ashley
- Department of Biology, Western Kentucky University, Bowling Green, KY, USA.
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5
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Becker DJ, Czirják GÁ, Rynda-Apple A, Plowright RK. Handling Stress and Sample Storage Are Associated with Weaker Complement-Mediated Bactericidal Ability in Birds but Not Bats. Physiol Biochem Zool 2019; 92:37-48. [PMID: 30481115 DOI: 10.1086/701069] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Variation in immune defense influences infectious disease dynamics within and among species. Understanding how variation in immunity drives pathogen transmission among species is especially important for animals that are reservoir hosts for zoonotic pathogens. Bats, in particular, have a propensity to host serious viral zoonoses without developing clinical disease themselves. The immunological adaptations that allow bats to host viruses without disease may be related to their adaptations for flight (e.g., in metabolism and mediation of oxidative stress). A number of analyses report greater richness of zoonotic pathogens in bats than in other taxa, such as birds (i.e., mostly volant vertebrates) and rodents (i.e., nonvolant small mammals), but immunological comparisons between bats and these other taxa are rare. To examine interspecific differences in bacterial killing ability (BKA), a functional measure of overall constitutive innate immunity, we use a phylogenetic meta-analysis to compare how BKA responds to the acute stress of capture and to storage time of frozen samples across the orders Aves and Chiroptera. After adjusting for host phylogeny, sample size, and total microbe colony-forming units, we find preliminary evidence that the constitutive innate immune defense of bats may be more resilient to handling stress and storage time than that of birds. This pattern was also similar when we analyzed the proportion of nonnegative and positive effect sizes per species, using phylogenetic comparative methods. We discuss potential physiological and evolutionary mechanisms by which complement proteins may differ between species orders and suggest future avenues for comparative field studies of immunity between sympatric bats, birds, and rodents in particular.
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Tsang SM, Wiantoro S, Veluz MJ, Simmons NB, Lohman DJ. Low Levels of Population Structure among Geographically Distant Populations of Pteropus vampyrus (Chiroptera: Pteropodidae). ACTA CHIROPTEROLOGICA 2018. [DOI: 10.3161/15081109acc2018.20.1.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Susan M. Tsang
- Department of Biology, City College and the Graduate Center, The City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
| | - Sigit Wiantoro
- Museum Zoologicum Bogoriense, Indonesian Institute of Sciences, Jl. Raya Jakarta-Bogor, Km. 46, Cibinong, 16911, Indonesia
| | - Maria Josefa Veluz
- Zoology Division, National Museum of the Philippines, Padres Burgos Ave, Ermita, Manila, 1000 Metro Manila, Philippines
| | - Nancy B. Simmons
- Department of Mammalogy, American Museum of Natural History, Central Park West and 79th Street, New York, NY, 10024, USA
| | - David J. Lohman
- Department of Biology, City College and the Graduate Center, The City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
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7
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McMichael L, Edson D, Smith C, Mayer D, Smith I, Kopp S, Meers J, Field H. Physiological stress and Hendra virus in flying-foxes (Pteropus spp.), Australia. PLoS One 2017; 12:e0182171. [PMID: 28767708 PMCID: PMC5540484 DOI: 10.1371/journal.pone.0182171] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/13/2017] [Indexed: 11/19/2022] Open
Abstract
Pteropid bats (flying-foxes) are the natural reservoir of Hendra virus, an emergent paramyxovirus responsible for fatal infection in horses and humans in Australia. Pteropus alecto (the Black flying-fox) and the paraphyletic P. conspicillatus (the Spectacled flying-fox) appear to be the primary reservoir hosts. Previous studies have suggested that physiological and ecological factors may underpin infection dynamics in flying-foxes, and subsequent spillover to horses and in turn humans. We sought to examine temporal trends in urinary cortisol concentration in wild Australian flying-fox populations, to elucidate the putative relationship between Hendra virus infection and physiological stress. Pooled and individual urine samples were non-invasively collected from under roosting flying-foxes at two latitudinally disparate regions in the eastern Australian state of Queensland. Hendra virus detection, and (in individual urine samples) sex and species determination were PCR-based. Urinary cortisol measurement used a validated enzyme immunoassay. We found no direct correlation between increased urinary cortisol and Hendra virus excretion, but our findings do suggest a biologically plausible association between low winter temperatures and elevated cortisol levels in P. alecto in the lower latitude Southeast Queensland roosts. We hypothesize an indirect association between low winter temperatures and increased Hendra virus infection and excretion, mediated by the physiological cost of thermoregulation. Our findings and our approach are directly relevant to elaboration of the disease ecology of Nipah virus and other emerging henipaviruses in bats. More broadly, they inform investigation of emerging disease infection dynamics across the wildlife/livestock/human interface.
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Affiliation(s)
- Lee McMichael
- University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia
- Biosecurity Queensland, Department of Agriculture and Fisheries, Brisbane, Queensland, Australia
- * E-mail:
| | - Daniel Edson
- Biosecurity Queensland, Department of Agriculture and Fisheries, Brisbane, Queensland, Australia
- Department of Agriculture and Water Resources, Canberra, Australian Capital Territory, Australia
| | - Craig Smith
- Biosecurity Queensland, Department of Agriculture and Fisheries, Brisbane, Queensland, Australia
| | - David Mayer
- Department of Agriculture and Fisheries, Brisbane, Queensland, Australia
| | - Ina Smith
- Australian Animal Health Laboratory, Geelong, Victoria, Australia
| | - Steven Kopp
- University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia
| | - Joanne Meers
- University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia
| | - Hume Field
- EcoHealth Alliance, New York, New York, United States of America
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8
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Hengjan Y, Pramono D, Takemae H, Kobayashi R, Iida K, Ando T, Kasmono S, Basri C, Fitriana YS, Arifin EMZ, Ohmori Y, Maeda K, Agungpriyono S, Hondo E. Daytime behavior of Pteropus vampyrus in a natural habitat: the driver of viral transmission. J Vet Med Sci 2017; 79:1125-1133. [PMID: 28496012 PMCID: PMC5487794 DOI: 10.1292/jvms.16-0643] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Flying foxes, the genus Pteropus, are considered viral reservoirs. Their
colonial nature and long flight capability enhance their ability to spread viruses
quickly. To understand how the viral transmission occurs between flying foxes and other
animals, we investigated daytime behavior of the large flying fox (Pteropus
vampyrus) in the Leuweung Sancang conservation area, Indonesia, by using
instantaneous scan sampling and all-occurrence focal sampling. The data were obtained from
0700 to 1700 hr, during May 11–25, 2016. Almost half of the flying foxes (46.9 ± 10.6% of
all recorded bats) were awake and showed various levels of activity during daytime. The
potential behaviors driving disease transmission, such as self-grooming, mating/courtship
and aggression, peaked in the early morning. Males were more active and spent more time on
sexual activities than females. There was no significant difference in time spent for
negative social behaviors between sexes. Positive social behaviors, especially maternal
cares, were performed only by females. Sexual activities and negative/positive social
behaviors enable fluid exchange between bats and thus facilitate intraspecies
transmission. Conflicts for living space between the flying foxes and the ebony leaf
monkey (Trachypithecus auratus) were observed, and this caused daily
roosting shifts of flying foxes. The ecological interactions between bats and other
wildlife increase the risk of interspecies infection. This study provides the details of
the flying fox’s behavior and its interaction with other wildlife in South-East Asia that
may help explain how pathogen spillover occurs in the wild.
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Affiliation(s)
- Yupadee Hengjan
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Didik Pramono
- Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor 16680, Indonesia
| | - Hitoshi Takemae
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Ryosuke Kobayashi
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Keisuke Iida
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Takeshi Ando
- Japan International Cooperation Agency (JICA), Jakarta 10270, Indonesia
| | - Supratikno Kasmono
- Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor 16680, Indonesia
| | - Chaerul Basri
- Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor 16680, Indonesia
| | | | - Eko M Z Arifin
- Livestock, Fisheries and Marine Services, Garut 44118, Indonesia
| | - Yasushige Ohmori
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Ken Maeda
- Laboratory of Veterinary Microbiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Srihadi Agungpriyono
- Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Bogor 16680, Indonesia
| | - Eiichi Hondo
- Laboratory of Animal Morphology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Kelm DH, Popa-Lisseanu AG, Dehnhard M, Ibáñez C. Non-invasive monitoring of stress hormones in the bat Eptesicus isabellinus - Do fecal glucocorticoid metabolite concentrations correlate with survival? Gen Comp Endocrinol 2016; 226:27-35. [PMID: 26673871 DOI: 10.1016/j.ygcen.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 09/29/2015] [Accepted: 12/04/2015] [Indexed: 12/27/2022]
Abstract
Chronic stress may negatively impact fitness and survival in wildlife. Stress hormone analysis from feces is a non-invasive tool for identifying stressors and deducing about individual and population level fitness. Although many bat populations are endangered, fecal stress hormone analysis has not been established in bats as a method for focusing conservation efforts. The isabelline serotine bat, Eptesicus isabellinus, is exposed to human disturbance as its roosts are mostly found in anthropogenic structures. Moreover, this bat is host to various diseases and survival rates between colonies may vary significantly. To validate the analysis of fecal glucocorticoid metabolites, we applied an adrenocorticotropic hormone (ACTH) challenge and tested four different enzyme immunoassays (EIA) for measuring glucocorticoid concentrations. Cortisol and its metabolites showed the highest increase in blood and feces after the ACTH challenge, but corticosterone and its metabolites also increased significantly. Baseline fecal cortisol metabolite (FCM) concentrations did not increase until 1.5h after the animals were captured, which is a convenient time lag for sample collection from captured animals. We furthermore compared baseline FCM concentrations between five colonies of E. isabellinus in Andalusia, Spain, and tested for their correlation with survival rates. FCM concentrations did not vary between colonies, but FCM levels increased with the animals' age. FCM analysis may prove a useful tool for identifying bat colonies that experience uncommon environmental stress. However, inter-individual variation in hormone secretion, due to factors such as age, may require additional information to properly interpret differences in hormone concentrations.
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Affiliation(s)
- Detlev H Kelm
- Estación Biológica de Doñana (CSIC), c/ Americo Vespucio s/n, 41092 Sevilla, Spain.
| | - Ana G Popa-Lisseanu
- Estación Biológica de Doñana (CSIC), c/ Americo Vespucio s/n, 41092 Sevilla, Spain
| | - Martin Dehnhard
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany
| | - Carlos Ibáñez
- Estación Biológica de Doñana (CSIC), c/ Americo Vespucio s/n, 41092 Sevilla, Spain
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10
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Parry-Jones K, Webster KN, Divljan A. Baseline levels of faecal glucocorticoid metabolites and indications of chronic stress in the vulnerable grey-headed flying-fox, Pteropus poliocephalus. AUSTRALIAN MAMMALOGY 2016. [DOI: 10.1071/am15030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The physiological stress hormone levels and physical condition of captured urban flying-foxes experiencing a food shortage were compared with those of free-living rural flying-foxes with access to supplementary food. Glucocorticoid hormone levels were determined by measuring glucocorticoid metabolites (GCMs) from the faeces of individual animals. The rural flying-foxes were in good condition with high Body Condition Indexes (BCIs) and low levels of GCMs, the range of which may be considered the baseline for this species. In comparison, urban flying-foxes had lower BCIs and elevated levels of GCMs: 75% had levels that were higher than the rural range and 30% were higher by an order of magnitude. Such elevated levels of glucocorticoid (‘stress’) hormones are characteristic of chronic stress. While urbanisation can cause chronic stress, given the low BCIs observed, it is more likely that food shortage was the major stressor in this study. While the rural male and female flying-foxes showed no significant differences in either their levels of faecal glucocorticoid metabolites or their BCIs, significantly different results were found between male and female urban flying-foxes: males were in relatively better condition than females but had higher levels of faecal glucocorticoid metabolites. The autumn and winter reproductive constraints on food-restricted flying-foxes probably explain the differences observed. Additional droppings collected under the urban colony gave similar results to those collected from captured flying-foxes at the same location, and could be a useful non-invasive method for determining the levels of physiological stress in flying-fox colonies.
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11
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Cockrem JF. Individual variation in glucocorticoid stress responses in animals. Gen Comp Endocrinol 2013; 181:45-58. [PMID: 23298571 DOI: 10.1016/j.ygcen.2012.11.025] [Citation(s) in RCA: 214] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 11/15/2012] [Accepted: 11/18/2012] [Indexed: 12/30/2022]
Abstract
When stimuli from the environment are perceived to be a threat or potential threat then animals initiate stress responses, with activation of the hypothalamo-pituitary-adrenal axis and secretion of glucocorticoid hormones (cortisol and corticosterone). Whilst standard deviation or standard error values are always reported, it is only when graphs of individual responses are shown that the extensive variation between animals is apparent. Some animals have little or no response to a stressor that evokes a relatively large response in others. Glucocorticoid responses of fish, amphibian, reptiles, birds, and mammals are considered in this review. Comparisons of responses between animals and groups of animals focused on responses to restraint or confinement as relatively standard stressors. Individual graphs could not be found in the literature for glucocorticoid responses to capture or restraint in fish or reptiles, with just one graph in mammals with the first sample was collected when animals were initially restrained. Coefficients of variation (CVs) calculated for parameters of glucocorticoid stress responses showed that the relative magnitudes of variation were similar in different vertebrate groups. The overall mean CV for glucocorticoid concentrations in initial (0 min) samples was 74.5%, and CVs for samples collected over various times up to 4 h were consistently between 50% and 60%. The factors that lead to the observed individual variation and the extent to which this variation is adaptive or non-adaptive are little known in most animals, and future studies of glucocorticoid responses in animals can focus on individual responses and their origins and significance.
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Affiliation(s)
- John F Cockrem
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand.
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12
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Lewanzik D, Kelm DH, Greiner S, Dehnhard M, Voigt CC. Ecological correlates of cortisol levels in two bat species with contrasting feeding habits. Gen Comp Endocrinol 2012; 177:104-12. [PMID: 22429728 DOI: 10.1016/j.ygcen.2012.02.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 01/17/2012] [Accepted: 02/28/2012] [Indexed: 11/18/2022]
Abstract
The immediate release of adrenal glucocorticoids can be crucial for an animal's survival when facing a stressor, but constantly elevated or exceptionally high glucocorticoid levels are usually detrimental for health. Although baseline and maximal secretion of glucocorticoids are regulated within narrow ranges within species, plasma glucocorticoid levels vary largely across vertebrates. We asked what ecological factors affect baseline plasma cortisol levels (CortI) and maximum levels (CortMax) following a physiological challenge through administration of adrenocorticotropic hormone (ACTH). Specifically, we studied whether seasonal fluctuations in food abundance correlate with the capacity of cortisol increases in two phyllostomid bat species with contrasting feeding habits: the sanguinivorous vampire bat (Desmodus rotundus) and the frugivorous short-tailed fruit bat (Carollia perspicillata). Both species coexist in habitats with various levels of seasonality (dry and rainforest). On a seasonal basis, resource abundance is more stable for vampire than for fruit bats, but previous studies suggested that daily foraging success may vary more for vampire than for fruit bats. CortI and CortMax varied seasonally in C. perspicillata from dry and rainforests, with the exception of CortMax in rainforest bats. Although we expected food availability to be stable year-round for vampire bats, we found CortI and CortMax of vampires to be higher during the rainy season than during the dry season. Also, we found CortMax to be higher in vampires from the rainforest than in those from the dry forest. CortMax of vampires were among the highest measured for a free-ranging mammal; a pattern that could be related to the species' vulnerability to starvation. We conclude that food availability modulates cortisol levels in free-ranging species that face seasonally fluctuating resources; in species, however, that benefit from food which is constantly abundant, other factors than food may become more important in modulating cortisol levels.
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Affiliation(s)
- Daniel Lewanzik
- Evolutionary Ecology Research Group, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany.
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Buffenstein R, Pinto M. Endocrine function in naturally long-living small mammals. Mol Cell Endocrinol 2009; 299:101-11. [PMID: 18674586 PMCID: PMC4399555 DOI: 10.1016/j.mce.2008.04.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 04/11/2008] [Indexed: 12/19/2022]
Abstract
The complex, highly integrative endocrine system regulates all aspects of somatic maintenance and reproduction and has been widely implicated as an important determinant of longevity in short-lived traditional model organisms of aging research. Genetic or experimental manipulation of hormone profiles in mice has been proven to definitively alter longevity. These hormonally induced lifespan extension mechanisms may not necessarily be relevant to humans and other long-lived organisms that naturally show successful slow aging. Long-lived species may have evolved novel anti-aging defenses germane to naturally retarding the aging process. Here, we examine the available endocrine data associated with the vitamin D, insulin, glucocorticoid and thyroid endocrine systems of naturally long-living small mammals. Generally, long-living rodents and bats maintain tightly regulated lower basal levels of these key pleiotropic hormones than shorter lived rodents. Similarities with genetically manipulated long-lived rodent models of aging suggest that evolutionary well-conserved hormonal mechanisms are integrally involved in lifespan determination.
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Affiliation(s)
- Rochelle Buffenstein
- The Sam and Ann Barshop Institute for Longevity and Aging Studies & Department of Physiology, University of Texas Health Science Center at San Antonio, TX 78245, United States.
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