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Veloso-Frías J, Soto-Gamboa M, Mastromonaco G, Acosta-Jamett G. Seasonal Hair Glucocorticoid Fluctuations in Wild Mice ( Phyllotis darwini) within a Semi-Arid Landscape in North-Central Chile. Animals (Basel) 2024; 14:1260. [PMID: 38731264 PMCID: PMC11083726 DOI: 10.3390/ani14091260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/15/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
Mammals in drylands face environmental challenges exacerbated by climate change. Currently, human activity significantly impacts these environments, and its effects on the energy demands experienced by individuals have not yet been determined. Energy demand in organisms is managed through elevations in glucocorticoid levels, which also vary with developmental and health states. Here, we assessed how anthropization, individual characteristics, and seasonality influence hair glucocorticoid concentration in the Darwin's leaf-eared mouse (Phyllotis darwini) inhabiting two areas with contrasting anthropogenic intervention in a semi-arid ecosystem of northern Chile. Hair samples were collected (n = 199) to quantify hair corticosterone concentration (HCC) using enzyme immunoassays; additionally, sex, body condition, and ectoparasite load were recorded. There were no differences in HCC between anthropized areas and areas protected from human disturbance; however, higher concentrations were recorded in females, and seasonal fluctuations were experienced by males. The results indicate that animals inhabiting semi-arid ecosystems are differentially stressed depending on their sex. Additionally, sex and season have a greater impact on corticosterone concentration than anthropogenic perturbation, possibly including temporal factors, precipitation, and primary production. The influence of sex and seasonality on HCC in P. darwini make it necessary to include these variables in future stress assessments of this species.
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Affiliation(s)
- Joseline Veloso-Frías
- Institute of Preventive Veterinary Medicine, Austral University of Chile, Valdivia 5090000, Chile;
| | - Mauricio Soto-Gamboa
- Institute of Environmental and Evolutionary Sciences, Austral University of Chile, Valdivia 5090000, Chile;
| | | | - Gerardo Acosta-Jamett
- Institute of Preventive Veterinary Medicine, Austral University of Chile, Valdivia 5090000, Chile;
- Center for Surveillance and Evolution of Infectious Diseases (CSEID), Austral University of Chile, Valdivia 5090000, Chile
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Correa LA, Aspillaga-Cid A, Bauer CM, Silva-Álvarez D, León C, Ramírez-Estrada J, Soto-Gamboa M, Hayes LD, Ebensperger LA. Social environment and anogenital distance length phenotype interact to explain testosterone levels in a communally rearing rodent: Part 1: The male side. Horm Behav 2024; 160:105479. [PMID: 38278060 DOI: 10.1016/j.yhbeh.2024.105479] [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: 08/30/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/28/2024]
Abstract
In vertebrates, male testosterone levels vary across the year being generally higher during the mating season relative to the offspring rearing season. However, male testosterone levels may also be associated with male anogenital distance (AGD) length (a proxy of prenatal androgen exposition), and influenced by the social group environment. In social species, it has been proposed that high levels of testosterone could be incompatible with the development of an amicable social environment. Thus, in these species, it is predicted that males have relatively low levels of testosterone. Our goal was to examine the potential association between male serum testosterone levels, season, male AGD length, and the social environment in the rodent Octodon degus under natural conditions. We quantified male serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in each social group, as well as the composition of groups, in terms of the AGD length of the female and male group mates, from 2009 to 2019. Our results revealed that male testosterone levels covary with season, being highest during the offspring rearing season. Additionally, male testosterone levels vary with male AGD length, and female and male social group environments. More importantly, male degus exhibit low levels of testosterone that are indistinguishable from female levels during offspring rearing season. Similar to other highly social mammals, where males and females live together year-round, male amicable behavior could be the best male mating strategy, thus leading to a reduction in circulating testosterone levels.
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Affiliation(s)
- Loreto A Correa
- Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino la Pirámide 5750, Huechuraba, Santiago, Chile.
| | - Antonia Aspillaga-Cid
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carolyn M Bauer
- Department of Biology, Swarthmore College, Swarthmore, PA, USA
| | - Danna Silva-Álvarez
- Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino la Pirámide 5750, Huechuraba, Santiago, Chile
| | - Cecilia León
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Ramírez-Estrada
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mauricio Soto-Gamboa
- Laboratorio de Ecología Conductual y Conservación, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Loren D Hayes
- Department of Biology, Geology and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA
| | - Luis A Ebensperger
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Correa LA, Aspillaga-Cid A, León C, Bauer CM, Ramírez-Estrada J, Hayes LD, Soto-Gamboa M, Ebensperger LA. Social environment and anogenital distance length phenotype interact to explain testosterone levels in a communally rearing rodent: Part 2: The female side. Horm Behav 2024; 160:105486. [PMID: 38295731 DOI: 10.1016/j.yhbeh.2024.105486] [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: 10/05/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 03/26/2024]
Abstract
Testosterone is known as a "male" hormone; however, females also synthetize testosterone, which influences female sexual and aggressive behavior. In female vertebrates, as in males, testosterone levels can vary seasonally. However, female testosterone levels may also be related with female anogenital distance (AGD) length phenotype (a proxy of prenatal androgen exposure), and the social group environment. We used data from a long-term rodent study (2009-2019) in a natural population of degus (Octodon degus) to examine the potential associations between female serum testosterone levels, season, female AGD phenotype, and social group composition. We quantified female serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in social groups, as well the composition of groups, in terms of the AGD of the female and male group mates. Our results indicate that female testosterone levels vary with season, being highest during the offspring rearing season. Additionally, female testosterone levels were associated with the number of male group-members and the AGD of male group-members but were not associated with female social environment and focal female AGD phenotype. Together, our results suggest that female testosterone levels are sensitive to intersexual interactions. Our results also reveal that female and male testosterone levels do not differ between the sexes, a finding previously reported only in rock hyraxes. We discuss how the complex social system of degus could be driving this physiological similarity between the sexes.
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Affiliation(s)
- Loreto A Correa
- Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino la Pirámide 5750, Huechuraba, Santiago, Chile.
| | - Antonia Aspillaga-Cid
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Carolyn M Bauer
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Loren D Hayes
- Department of Biology, Geology and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA
| | - Mauricio Soto-Gamboa
- Laboratorio de Ecología Conductual y Conservación, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
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Yao YZ, Brennan FE, Carvajal CA, Vecchiola A, Tapia-Castillo A, Fardella CE, Fuller PJ. Cortisol resistance in the degu (Octodon degus). Steroids 2022; 184:109037. [PMID: 35429494 DOI: 10.1016/j.steroids.2022.109037] [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: 01/28/2022] [Revised: 03/23/2022] [Accepted: 04/11/2022] [Indexed: 11/21/2022]
Abstract
Cortisol resistance has also been reported in the degu, Octodon degus, a New World hystricomorph endemic to central Chile. The degu is used as a model for studies of stress and diurnal rhythms, parental behaviour and female masculinization. Another New World hystricomorph, the guinea pig, also exhibits glucocorticoid resistance, a result of amino acid sequences that differ from other mammalian glucocorticoid receptors (GR). Mutations in the ligand-binding domain of the human GR have been identified in familial or sporadic generalised cortisol resistance as have variants in the guinea pig. To address the possibility that the high levels of cortisol observed in the degu are a result of the same or similar sequence variations observed in the guinea pig GR, we have cloned, expressed and characterised the ligand-binding domain (LBD) of the degu GR. Somewhat unexpectedly, neither the amino acids nor the region involved in the resistance observed in the guinea pig GR are relevant in the degu GR. The relative resistance to cortisol observed in the degu GR is conferred by the substitution of two isoleucine residues, which are highly conserved in the GR across species, with a valine doublet. These amino acids lie in the region between helices 5 and 6 of the GR LBD, a region known to be important in determining the affinity of ligand-binding in steroid receptors.
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Affiliation(s)
- Yi-Zhou Yao
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research and the Monash University, Department of Molecular Translational Science, Clayton, Victoria 3168, Australia
| | - Francine E Brennan
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research and the Monash University, Department of Molecular Translational Science, Clayton, Victoria 3168, Australia
| | - Cristian A Carvajal
- Departamento de Endocrinologia, Facultad de Medicina, and Centro Traslacional de Endocrinología (CETREN UC) Pontificia, Universidad Catolica de Chile, Santiago, Chile
| | - Andrea Vecchiola
- Departamento de Endocrinologia, Facultad de Medicina, and Centro Traslacional de Endocrinología (CETREN UC) Pontificia, Universidad Catolica de Chile, Santiago, Chile
| | - Alejandra Tapia-Castillo
- Departamento de Endocrinologia, Facultad de Medicina, and Centro Traslacional de Endocrinología (CETREN UC) Pontificia, Universidad Catolica de Chile, Santiago, Chile
| | - Carlos E Fardella
- Departamento de Endocrinologia, Facultad de Medicina, and Centro Traslacional de Endocrinología (CETREN UC) Pontificia, Universidad Catolica de Chile, Santiago, Chile
| | - Peter J Fuller
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research and the Monash University, Department of Molecular Translational Science, Clayton, Victoria 3168, Australia.
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5
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Caniklioğlu M, Öztekin Ü, Caniklioğlu A, Selmi V, Sarı S, Işıkay L. Can Annual Daylight Cycles and Seasons Have an Effect on Male Sexual Functions? Cureus 2021; 13:e18879. [PMID: 34804728 PMCID: PMC8599110 DOI: 10.7759/cureus.18879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2021] [Indexed: 11/09/2022] Open
Abstract
Introduction Mammals' sexual functions exhibit seasonal variations that have been attributed to changes in the daylight. In this study, taking into consideration endocrine and psychogenic status, we aimed to investigate whether human males experience changes in erectile functions and sexual desire depending on daylight periods and seasons, and whether periodicity exists in human sexual behavior. Materials and methods International Index of Erectile Function (IIEF) and psychiatric scale scores of 221 male patients were evaluated. In addition, hormonal parameters of the patients were examined. These data were first evaluated in two groups (summer and winter) according to local daylight amounts the participants received. Then IIEF scores were also analyzed according to four conventional seasons (winter, spring, summer, and autumn). Results There was no significant difference in laboratory data, psychiatric scale scores and IIEF evaluations between summer and winter groups. Moreover, no significant difference was found in terms of sexual desire and erectile functions in terms of four seasons (p > 0.05). Conclusion According to the results of this study, there is no periodicity in human sexual functions both in relation to daylight and four seasons.
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Affiliation(s)
| | | | - Ayşen Caniklioğlu
- Clinical Biochemistry, Bozok University Faculty of Medicine, Yozgat, TUR
| | - Volkan Selmi
- Urology, Bozok University Faculty of Medicine, Yozgat, TUR
| | - Sercan Sarı
- Urology, Bozok University Faculty of Medicine, Yozgat, TUR
| | - Levent Işıkay
- Urology, Bozok University Faculty of Medicine, Yozgat, TUR
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6
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Octodon degus: a natural model of multimorbidity for ageing research. Ageing Res Rev 2020; 64:101204. [PMID: 33152453 DOI: 10.1016/j.arr.2020.101204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 12/14/2022]
Abstract
Integrating the multifactorial processes co-occurring in both physiological and pathological human conditions still remains one of the main challenges in translational investigation. Moreover, the impact of age-associated disorders has increased, which underlines the urgent need to find a feasible model that could help in the development of successful therapies. In this sense, the Octodon degus has been indicated as a 'natural' model in many biomedical areas, especially in ageing. This rodent shows complex social interactions and high sensitiveness to early-stressful events, which have been used to investigate neurodevelopmental processes. Interestingly, a high genetic similarity with some key proteins implicated in human diseases, such as apolipoprotein-E, β-amyloid or insulin, has been demonstrated. On the other hand, the fact that this animal is diurnal has provided important contribution in the field of circadian biology. Concerning age-related diseases, this rodent could be a good model of multimorbidity since it naturally develops cognitive decline, neurodegenerative histopathological hallmarks, visual degeneration, type II diabetes, endocrinological and metabolic dysfunctions, neoplasias and kidneys alterations. In this review we have collected and summarized the studies performed on the Octodon degus through the years that support its use as a model for biomedical research, with a special focus on ageing.
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7
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Rivera DS, Lindsay CB, Oliva CA, Codocedo JF, Bozinovic F, Inestrosa NC. Effects of long-lasting social isolation and re-socialization on cognitive performance and brain activity: a longitudinal study in Octodon degus. Sci Rep 2020; 10:18315. [PMID: 33110163 PMCID: PMC7591540 DOI: 10.1038/s41598-020-75026-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/27/2020] [Indexed: 12/18/2022] Open
Abstract
Social isolation is considered a stressful situation that results in increased physiological reactivity to novel stimuli, altered behaviour, and impaired brain function. Here, we investigated the effects of long-term social isolation on working memory, spatial learning/memory, hippocampal synaptic transmission, and synaptic proteins in the brain of adult female and male Octodon degus. The strong similarity between degus and humans in social, metabolic, biochemical, and cognitive aspects, makes it a unique animal model that can be highly applicable for further social, emotional, cognitive, and aging studies. These animals were socially isolated from post-natal and post-weaning until adulthood. We also evaluated if re-socialization would be able to compensate for reactive stress responses in chronically stressed animals. We showed that long-term social isolation impaired the HPA axis negative feedback loop, which can be related to cognitive deficits observed in chronically stressed animals. Notably, re-socialization restored it. In addition, we measured physiological aspects of synaptic transmission, where chronically stressed males showed more efficient transmission but deficient plasticity, as the reverse was true on females. Finally, we analysed synaptic and canonical Wnt signalling proteins in the hypothalamus, hippocampus, and prefrontal cortex, finding both sex- and brain structure-dependent modulation, including transient and permanent changes dependent on stress treatment.
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Affiliation(s)
- Daniela S Rivera
- GEMA Center for Genomics, Ecology and Environment, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Santiago, Chile.
| | - Carolina B Lindsay
- Center of Aging and Regeneration UC (CARE-UC), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carolina A Oliva
- Center of Aging and Regeneration UC (CARE-UC), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Francisco Codocedo
- Center of Aging and Regeneration UC (CARE-UC), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisco Bozinovic
- Center for Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nibaldo C Inestrosa
- Center of Aging and Regeneration UC (CARE-UC), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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8
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Developmental changes in the endocrine stress response in orangutans (Pongo pygmaeus). J Comp Physiol B 2019; 189:659-672. [DOI: 10.1007/s00360-019-01235-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/16/2019] [Accepted: 09/12/2019] [Indexed: 12/11/2022]
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9
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Vera F, Antenucci CD, Zenuto RR. Different regulation of cortisol and corticosterone in the subterranean rodent Ctenomys talarum: Responses to dexamethasone, angiotensin II, potassium, and diet. Gen Comp Endocrinol 2019; 273:108-117. [PMID: 29782839 DOI: 10.1016/j.ygcen.2018.05.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 05/09/2018] [Accepted: 05/17/2018] [Indexed: 12/13/2022]
Abstract
When harmful environmental stimuli occur, glucocorticoids (GCs), cortisol and corticosterone are currently used to evaluate stress status in vertebrates, since their secretions are primarily associated to an increased activity of the hypothalamic-pituitaryadrenal (HPA) axis. To advance in our comprehension about GCs regulation, we evaluated the subterranean rodent Ctenomys talarum to assess cortisol and corticosterone response to (1) the negative feedback of the HPA axis using the dexamethasone (DEX) suppression test, (2) angiotensin II (Ang II), (3) potassium (K+) intake, and (4) different diets (vegetables, grasses, acute fasting). Concomitantly, several indicators of individual condition (body mass, neutrophil to lymphocyte ratio, blood glucose, triglycerides and hematocrit) were measured for diet treatments. Results confirm the effect of DEX on cortisol and corticosterone in recently captured animals in the field but not on corticosterone in captive animals. Data suggest that Ang II is capable of stimulating corticosterone, but not cortisol, secretion. Neither cortisol nor corticosterone were responsive to K+ intake. Cortisol levels increased in animals fed with grasses in comparison to those fed with vegetables while corticosterone levels were unaffected by diet type. Moreover, only cortisol responded to fasting. Overall, these results confirm that cortisol and corticosterone are not interchangeable hormones in C. talarum.
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Affiliation(s)
- Federico Vera
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - C Daniel Antenucci
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - Roxana R Zenuto
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
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10
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Bauer CM, Correa LA, Ebensperger LA, Romero LM. Stress, sleep, and sex: A review of endocrinological research in Octodon degus. Gen Comp Endocrinol 2019; 273:11-19. [PMID: 29545088 DOI: 10.1016/j.ygcen.2018.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 02/20/2018] [Accepted: 03/11/2018] [Indexed: 10/17/2022]
Abstract
The Common Degu (Octodon degus) is a small rodent endemic to central Chile. It has become an important model for comparative vertebrate endocrinology because of several uncommon life-history features - it is diurnal, shows a high degree of sociality, practices plural breeding with multiple females sharing natal burrows, practices communal parental care, and can easily be studied in the laboratory and the field. Many studies have exploited these features to make contributions to comparative endocrinology. This review summarizes contributions in four major areas. First are studies on degu stress responses, focusing on seasonal changes in glucocorticoid (GC) release, impacts of parental care on offspring GC responses, and fitness consequences of individual variations of GC responses. These studies have helped confirm the ecological relevance of stress responses. Second are studies exploring diurnal circadian rhythms of melatonin and sex steroids. These studies have formed important work translating circadian biology from nocturnal laboratory rodents to diurnal humans. Third are studies that exploit the open nature of degu natural habitat, combined with laboratory studies, to explore the impact of testosterone on agonistic behavior. Studies have focused primarily on male:male, female:female, male:female, and parental behaviors. Fourth, are contributions to the study of female masculinization from male siblings in the uterus. These studies have focused on both the behavioral consequences of masculinization and the impact of those behaviors on fitness. Taken together, the studies reviewed here have formed a strong foundation for further studies in the degu so that future studies can address how endocrinological components underlie new mechanistic connections to the ecological effects on behavior and fitness.
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Affiliation(s)
- Carolyn M Bauer
- Biology Department, Adelphi University, Garden City, NY, USA.
| | - Loreto A Correa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile; Departamento de Ecología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
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Zatra Y, Aknoun-Sail N, Kheddache A, Benmouloud A, Charallah S, Moudilou EN, Exbrayat JM, Khammar F, Amirat Z. Seasonal changes in plasma testosterone and cortisol suggest an androgen mediated regulation of the pituitary adrenal axis in the Tarabul's gerbil Gerbillus tarabuli (Thomas, 1902). Gen Comp Endocrinol 2018; 258:173-183. [PMID: 28811197 DOI: 10.1016/j.ygcen.2017.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/23/2017] [Accepted: 08/11/2017] [Indexed: 12/05/2022]
Abstract
In the desert gerbil Gerbillus tarabuli (Thomas, 1902), cortisol is the main glucocorticosteroid produced by the adrenal glands. Plasma cortisol concentrations show highest values when testosterone is reduced and lowest values during the breeding season which occurs from early winter to late spring. In order to specify the implication of testicular androgens in these corticosteroid seasonal variations we investigated the effects induced by gonadectomy performed during the breeding season on the pituitary adrenal axis. The animals collected in winter were assessed into three groups: sham-operated (Controls; n=13), gonadectomised (GDX; n=13) and testosterone replaced gonadectomised (GDX+T; n=13). Physiological replacement of testosterone enanthate (75µg/100gb.w./twice daily) was applied during one week, while GDX group received the vehicle (40µL sesame oil) alone. The right adrenal glands removed from euthanized animals were fixed for histomorphometry and androgen receptors (ARs) immunohistochemistry and the left ones were frozen with plasma samples until hormonal assays. Gonadectomy induces the enlargement of the adrenal cortex essentially due to that of zonae fasciculata (ZF) and reticularis (ZR) and perimedullary connective tissue which is abundant in the gerbil adrenals. The ARs immunostaining present at both cytoplasmic and nucleus level, is enhanced intensely in the ZR and moderately in the ZF and zona glomerulosa (ZG) cells. GDX group shows reduced plasma ACTH concentration (p=0.0126) by 61% despite the increase in cortisol concentration occurring both in plasma (+216%; p=0.0436) and adrenal tissue (+117%; p=0.0348). Plasma aldosterone is also enhanced significantly (p=0.0147) by 189% but androstenedione synthesis increased in adrenal tissue (p=0.0459) by 65% instead a decrease at circulatory level (p=0.0355) by 58% due to lack of testicular origin. So, testosterone deprivation activates corticosteroidogenesis also evidenced by the adrenal structure changes and the gonadectomy-induced increase in the plasma cholesterol. All of the gonadectomy-induced responses are reversible after physiological testosterone replacement. We conclude that the assessment of circulating adrenocorticotropic hormone (ACTH) concentrations together with cortisol levels essentially, reflecting the hypothalamic-pituitary adrenal (HPA) axis feedback loop control during the annual endogenous changes of testosterone secretion, represents a well-adapted response of this desert species living in an extreme environment.
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Affiliation(s)
- Yamina Zatra
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Naouel Aknoun-Sail
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Arezki Kheddache
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Abdelouafi Benmouloud
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Salima Charallah
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Elara N Moudilou
- Université de Lyon, UMRS 449, Laboratoire de Biologie Générale, Université Catholique de Lyon, Reproduction et Développement Comparé, EPHE, 10 place des archives, 69288 Lyon Cedex 02, France.
| | - Jean-Marie Exbrayat
- Université de Lyon, UMRS 449, Laboratoire de Biologie Générale, Université Catholique de Lyon, Reproduction et Développement Comparé, EPHE, 10 place des archives, 69288 Lyon Cedex 02, France.
| | - Farida Khammar
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Zaina Amirat
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
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Fauteux D, Gauthier G, Berteaux D, Bosson C, Palme R, Boonstra R. Assessing Stress in Arctic Lemmings: Fecal Metabolite Levels Reflect Plasma Free Corticosterone Levels. Physiol Biochem Zool 2017; 90:370-382. [DOI: 10.1086/691337] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Lorioux S, Angelier F, Lourdais O. Are glucocorticoids good indicators of pregnancy constraints in a capital breeder? Gen Comp Endocrinol 2016; 232:125-33. [PMID: 27090427 DOI: 10.1016/j.ygcen.2016.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 03/31/2016] [Accepted: 04/09/2016] [Indexed: 12/24/2022]
Abstract
Pregnancy imposes a substantial energetic demand on the mother (i.e. metabolic costs of pregnancy) and is often associated with modified maternal behavior and increased physical burdens that make females more vulnerable to predation. The Hypothalamic-Pituitary-Adrenal axis plays a fundamental role in reproduction through hormonal control of energy regulation and parental care. Therefore, evaluating the changes in baseline and stress-induced glucocorticoid levels in response to pregnancy may provide a robust tool to assess not only the constraints of gestation but also the way females may adjust to these constraints. In this study, we measured baseline and stress-induced corticosterone (CORT) concentrations in pregnant and non-pregnant aspic vipers (Vipera aspis), which are capital breeders. We also measured muscle condition (tail width) and locomotion performance (traction force) because these are robust proxies of protein mobilization associated with fasting. Baseline CORT concentration increased significantly over time in pregnant females, while they were lower and stable in non-reproductive females. Pregnant females had lower muscle condition at the onset of the study and tail width was negatively correlated with CORT concentration in this group. Contrary to our prediction, the stress response was not attenuated in pregnant females, but was proportional to baseline CORT concentration. Our results suggest that baseline CORT variations are closely related to energy constraints and structural protein mobilization in this capital breeder.
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Affiliation(s)
- Sophie Lorioux
- Centre d'Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers en Bois, France; Université de Poitiers, 40 Avenue du recteur Pineau, 85022 Poitiers, France; School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
| | - Frédéric Angelier
- Centre d'Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers en Bois, France
| | - Olivier Lourdais
- Centre d'Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers en Bois, France; School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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Bauer CM, Ebensperger LA, León C, Ramírez-Estrada J, Hayes LD, Romero LM. Postnatal Development of the Degu (Octodon degus) Endocrine Stress Response Is Affected by Maternal Care. ACTA ACUST UNITED AC 2016; 325:304-17. [DOI: 10.1002/jez.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/30/2016] [Accepted: 04/15/2016] [Indexed: 01/15/2023]
Affiliation(s)
| | - Luis A. Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Loren D. Hayes
- Department of Biological and Environmental Sciences; University of Tennessee at Chattanooga; Chattanooga Tennessee
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Bauer CM, Hayes LD, Ebensperger LA, Ramírez-Estrada J, León C, Davis GT, Romero LM. Maternal stress and plural breeding with communal care affect development of the endocrine stress response in a wild rodent. Horm Behav 2015. [PMID: 26222493 DOI: 10.1016/j.yhbeh.2015.07.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Maternal stress can significantly affect offspring fitness. In laboratory rodents, chronically stressed mothers provide poor maternal care, resulting in pups with hyperactive stress responses. These hyperactive stress responses are characterized by high glucocorticoid levels in response to stressors plus poor negative feedback, which can ultimately lead to decreased fitness. In degus (Octodon degus) and other plural breeding rodents that exhibit communal care, however, maternal care from multiple females may buffer the negative impact on pups born to less parental mothers. We used wild, free-living degus to test this hypothesis. After parturition, we manipulated maternal stress by implanting cortisol pellets in 0%, 50-75%, or 100% of adult females within each social group. We then sampled pups for baseline and stress-induced cortisol, negative feedback efficacy, and adrenal sensitivity. From groups where all mothers were implanted with cortisol, pups had lower baseline cortisol levels and male pups additionally had weaker negative feedback compared to 0% or 50-75% implanted groups. Contrary to expectations, stress-induced cortisol did not differ between treatment groups. These data suggest that maternal stress impacts some aspects of the pup stress response, potentially through decreased maternal care, but that presence of unstressed mothers may mitigate some of these effects. Therefore, one benefit of plural breeding with communal care may be to buffer post-natal stress.
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Affiliation(s)
| | - Loren D Hayes
- Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, TN, USA
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Garrett T Davis
- Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, TN, USA
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Lapointe MA, Bauer CM, Ebensperger LA, Reed JM, Romero LM. Livetrapping is not biased by the endocrine stress response: a preliminary study in the degu (Octodon degus). J Mammal 2015. [DOI: 10.1093/jmammal/gyv081] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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DETECTION OF SEASONAL WEIGHT LOSS AND A SEROLOGIC SURVEY OF POTENTIAL PATHOGENS IN WILD PALLAS' CATS (FELIS[OTOCOLOBUS]MANUL) OF THE DAURIAN STEPPE, RUSSIA. J Wildl Dis 2014; 50:188-94. [DOI: 10.7589/2013-03-068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Quispe R, Villavicencio CP, Addis E, Wingfield JC, Vasquez RA. Seasonal variations of basal cortisol and high stress response to captivity in Octodon degus, a mammalian model species. Gen Comp Endocrinol 2014; 197:65-72. [PMID: 24368258 DOI: 10.1016/j.ygcen.2013.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 12/10/2013] [Accepted: 12/16/2013] [Indexed: 11/20/2022]
Abstract
Across vertebrates, the hypothalamic-pituitary-adrenal axis is a conserved neuroendocrine network that responds to changing environments and involves the release of glucocorticoids into the blood. Few studies have been carried out concerning mammalian adrenal regulation in wild species either in the laboratory or field, and even fewer have been able to determine true glucocorticoid baselines. We studied the South-American caviomorph rodent Octodon degus, a diurnal and social mammal that has become an important species in the biological research. First, we determined the plasma cortisol baseline and the acute stress concentrations during the non-reproductive and mating seasons in free-living individuals. Second, using the same protocol we assessed the impact of long-term captivity on the adrenal function in wild-caught degus and degus born in laboratory. Third, we examined laboratory groups formed with degus taken from two distant natural populations; one of them originally occurs at the Andes Mountains in high altitude conditions. The data revealed seasonal modulation of basal cortisol in the wild associated with mating. In laboratory, degus presented higher cortisol stress responses, with greater magnitudes shown in degus born and reared in captivity. No differences between populations were found. The results suggest differential regulatory mechanisms between basal and stress-induced cortisol levels, and context dependence of cortisol modulation in a mammalian species.
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Affiliation(s)
- Rene Quispe
- Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
| | - Camila P Villavicencio
- Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
| | - Elizabeth Addis
- Department of Biological Sciences, University of Washington, 24 Kincaid Hall, Box 351800, Seattle, WA 98195, USA
| | - John C Wingfield
- Department of Biological Sciences, University of Washington, 24 Kincaid Hall, Box 351800, Seattle, WA 98195, USA
| | - Rodrigo A Vasquez
- Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
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Bauer CM, Hayes LD, Ebensperger LA, Romero LM. Seasonal variation in the degu (Octodon degus) endocrine stress response. Gen Comp Endocrinol 2014; 197:26-32. [PMID: 24321176 DOI: 10.1016/j.ygcen.2013.11.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 11/23/2013] [Accepted: 11/28/2013] [Indexed: 10/25/2022]
Abstract
Many wild animals show seasonal variation in circulating levels of stress hormones. Seasonal changes in the stress response may help animals better cope with the different challenges faced during each life history stage. We determined the seasonal stress profile of wild, free-living degus in Chile. Female degus were sampled during non-breeding (January), mating/early gestation (July), late gestation (August), and lactation (1st litter-September, 2nd litter-January). Male degus were sampled during the first three time-points. We measured baseline cortisol (CORT), stress-induced CORT, and negative feedback efficacy using a dexamethasone suppression test. While we found that neither males nor females showed seasonal variation in baseline CORT or negative feedback levels, we did find significant seasonal variation in stress-induced CORT levels of both sexes. Male stress-induced CORT was lowest during mating while female stress-induced CORT was highest during late gestation and lactation. Overall, females had higher stress-induced CORT compared to males. Our data suggest that stress-induced levels of CORT are highest during periods with increased chance of stressor exposure or times of positive energy balance. Consequently, CORT responses to stress appear to be regulated according to different life history needs.
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Affiliation(s)
| | - Loren D Hayes
- Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, TN, USA
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Ghosal R, Ganswindt A, Seshagiri PB, Sukumar R. Endocrine correlates of musth in free-ranging Asian elephants (Elephas maximus) determined by non-invasive faecal steroid hormone metabolite measurements. PLoS One 2013; 8:e84787. [PMID: 24358371 PMCID: PMC3866162 DOI: 10.1371/journal.pone.0084787] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/26/2013] [Indexed: 11/30/2022] Open
Abstract
The occurrence of musth, a period of elevated levels of androgens and heightened sexual activity, has been well documented for the male Asian elephant (Elephas maximus). However, the relationship between androgen-dependent musth and adrenocortical function in this species is unclear. The current study is the first assessment of testicular and adrenocortical function in free-ranging male Asian elephants by measuring levels of testosterone (androgen) and cortisol (glucocorticoid – a physiological indicator of stress) metabolites in faeces. During musth, males expectedly showed significant elevation in faecal testosterone metabolite levels. Interestingly, glucocorticoid metabolite concentrations remained unchanged between musth and non-musth periods. This observation is contrary to that observed with wild and captive African elephant bulls and captive Asian bull elephants. Our results show that musth may not necessarily represent a stressful condition in free-ranging male Asian elephants.
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Affiliation(s)
- Ratna Ghosal
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
| | - André Ganswindt
- Endocrine Research Laboratory, Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Republic of South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, Republic of South Africa
| | - Polani B. Seshagiri
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Raman Sukumar
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
- * E-mail:
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Woodruff JA, Lacey EA, Bentley GE, Kriegsfeld LJ. Effects of social environment on baseline glucocorticoid levels in a communally breeding rodent, the colonial tuco-tuco (Ctenomys sociabilis). Horm Behav 2013; 64:566-72. [PMID: 23928366 DOI: 10.1016/j.yhbeh.2013.07.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 07/28/2013] [Accepted: 07/29/2013] [Indexed: 11/30/2022]
Abstract
The social environment in which an animal lives can profoundly impact its physiology, including glucocorticoid (GC) responses to external stressors. In social, group-living species, individuals may face stressors arising from regular interactions with conspecifics as well as those associated with basic life history needs such as acquiring food or shelter. To explore the relative contributions of these two types of stressors on glucocorticoid physiology in a communally breeding mammal, we characterized baseline GC levels in female colonial tuco-tucos (Ctenomys sociabilis), which are subterranean rodents endemic to southwestern Argentina. Long-term field studies have revealed that while about half of all yearling female C. sociabilis live and breed alone, the remainder live and breed within their natal group. We assessed the effects of this intraspecific variation in social environment on GC physiology by comparing concentrations of baseline fecal corticosterone metabolite (fCM) for (1) lone and group-living yearling females in a free-living population of C. sociabilis and (2) captive yearling female C. sociabilis that had been experimentally assigned to live alone or with conspecifics. In both cases, lone females displayed significantly higher mean baseline fCM concentrations. Data from free-living animals indicated that this outcome arose from differences in circadian patterns of GC production. fCM concentrations for group-living animals declined in the afternoon while fCM in lone individuals did not. These findings suggest that for C. sociabilis, stressors associated with basic life history functions present greater challenges than those arising from interactions with conspecifics. Our study is one of the first to examine GC levels in a plural-breeding mammal in which the effects of group-living are not confounded by differences in reproductive or dominance status, thereby generating important insights into the endocrine consequences of group-living.
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Affiliation(s)
- Julie A Woodruff
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Bauer CM, Skaff NK, Bernard AB, Trevino JM, Ho JM, Romero LM, Ebensperger LA, Hayes LD. Habitat type influences endocrine stress response in the degu (Octodon degus). Gen Comp Endocrinol 2013; 186:136-44. [PMID: 23518483 DOI: 10.1016/j.ygcen.2013.02.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 02/21/2013] [Accepted: 02/23/2013] [Indexed: 11/30/2022]
Abstract
While many studies have examined whether the stress response differs between habitats, few studies have examined this within a single population. This study tested whether habitat differences, both within-populations and between-populations, relate to differences in the endocrine stress response in wild, free-living degus (Octodon degus). Baseline cortisol (CORT), stress-induced CORT, and negative feedback efficacy were measured in male and female degus from two sites and three habitats within one site during the mating/early gestation period. Higher quality cover and lower ectoparasite loads were associated with lower baseline CORT concentrations. In contrast, higher stress-induced CORT but stronger negative feedback efficacy were associated with areas containing higher quality forage. Stress-induced CORT and body mass were positively correlated in female but not male degus across all habitats. Female degus had significantly higher stress-induced CORT levels compared to males. Baseline CORT was not correlated with temperature at time of capture and only weakly correlated with rainfall. Results suggest that degus in habitats with good cover quality, low ectoparasite loads, and increased food availability have decreased endocrine stress responses.
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Ebensperger LA, Tapia D, Ramírez-Estrada J, León C, Soto-Gamboa M, Hayes LD. Fecal cortisol levels predict breeding but not survival of females in the short-lived rodent, Octodon degus. Gen Comp Endocrinol 2013; 186:164-71. [PMID: 23524002 DOI: 10.1016/j.ygcen.2013.02.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/20/2013] [Accepted: 02/23/2013] [Indexed: 12/01/2022]
Abstract
The cort-adaptation hypothesis indicates that an association between glucocorticoid (cort) levels and fitness may vary with the extent to which reproduction or breeding effort is a major determinant of cort levels. Support for a context dependent association between cort and fitness comes mostly from relatively long-lived, bird species. We tested the hypothesis that there are gender and context (life-history) specific cort-fitness relationships in degus, a short-lived and generally semelparous social rodent. In particular, we used demographical records on a natural population to estimate adult survival through seasons and years and linked that to records of baseline cort (based on fecal cortisol metabolites). We found no evidence for a direct relationship between baseline cort and adult survival across seasons, and this lack of association was recorded irrespective of sex and life history stage. Yet, cort levels during early lactation predicted the probability that females produce a second litter during the same breeding season, supporting a connection between baseline cort levels and breeding effort. Overall, the differential effects of cort on survival and breeding supported that the extent of cort-fitness relationships depends on the fitness component examined.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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VERA FEDERICO, ZENUTO ROXANARITA, ANTENUCCI CARLOSDANIEL. Differential Responses of Cortisol and Corticosterone to Adrenocorticotropic Hormone (ACTH) in a Subterranean Rodent (Ctenomys talarum). ACTA ACUST UNITED AC 2012; 317:173-84. [DOI: 10.1002/jez.1711] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Washington IM, Van Hoosier G. Clinical Biochemistry and Hematology. THE LABORATORY RABBIT, GUINEA PIG, HAMSTER, AND OTHER RODENTS 2012. [PMCID: PMC7150282 DOI: 10.1016/b978-0-12-380920-9.00003-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
This chapter discusses the clinical biochemistry and hematology of the rabbit (Oryctolagus cuniculus), guinea pig (Cavia porcellus), hamster (Mesocricetus auratus), and other rodents, including the gerbil (Meriones unguiculatus), chinchilla (Chinchilla laniger), degu (Octodon degus), deer mouse (Peromyscus maniculatus), dormouse (Gliridae family), kangaroo rat (Dipodomys spp.), cotton rat (Sigmodon hispidus), and sand rat (Psammomys obesus). The chapter begins with a review of sample collection and preparation, and a description of commonly measured parameters and analytical techniques. The reference values, sources of variation, and unique characteristics are then presented for each species, as available. Many variables affect the parameters of clinical biochemistry and hematology including methods of sample collection and preparation, equipment, reagents, and methods of analysis, as well as the age, sex, breed, and environment of the animals being sampled. Values obtained from a clinical case are usually compared with reference values that are either produced in the same laboratory or in a similar group of animals, or cited in the literature. Optimal sites for blood collection vary between laboratory animals and are described in this chapter for each species for which information is available. Total blood volume of the rabbit is discussed in the Hematology section of the chapter. The rabbit is recognized as a valuable model for human disturbances in lipid metabolism, such as the metabolic syndrome and hypercholesterolemia leading to atherosclerosis. Hematology is the study of blood and blood-forming organs, including the diagnosis, treatment, and prevention of diseases of the blood, bone marrow, and immunologic, hemostatic, and vascular systems. Hematologic analysis is often used for the diagnosis and treatment of animal diseases.
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Ebensperger LA, Ramírez-Estrada J, León C, Castro RA, Tolhuysen LO, Sobrero R, Quirici V, Burger JR, Soto-Gamboa M, Hayes LD. Sociality, glucocorticoids and direct fitness in the communally rearing rodent, Octodon degus. Horm Behav 2011; 60:346-52. [PMID: 21777588 DOI: 10.1016/j.yhbeh.2011.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/21/2011] [Accepted: 07/01/2011] [Indexed: 11/16/2022]
Abstract
While ecological causes of sociality (or group living) have been identified, proximate mechanisms remain less clear. Recently, close connections between sociality, glucocorticoid hormones (cort) and fitness have been hypothesized. In particular, cort levels would reflect a balance between fitness benefits and costs of group living, and therefore baseline cort levels would vary with sociality in a way opposite to the covariation between sociality and fitness. However, since reproductive effort may become a major determinant of stress responses (i.e., the cort-adaptation hypothesis), cort levels might also be expected to vary with sociality in a way similar to the covariation between sociality and fitness. We tested these expectations during three years in a natural population of the communally rearing degu, Octodon degus. During each year we quantified group membership, measured fecal cortisol metabolites (a proxy of baseline cort levels under natural conditions), and estimated direct fitness. We recorded that direct fitness decreases with group size in these animals. Secondly, neither group size nor the number of females (two proxies of sociality) influenced mean (or coefficient of variation, CV) baseline cortisol levels of adult females. In contrast, cortisol increased with per capita number of offspring produced and offspring surviving to breeding age during two out of three years examined. Together, our results imply that variation in glucocorticoid hormones is more linked to reproductive challenge than to the costs of group living. Most generally, our study provided independent support to the cort-adaptation hypothesis, according to which reproductive effort is a major determinant, yet temporally variable, influence on cort-fitness covariation.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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Hagenauer MH, Ku JH, Lee TM. Chronotype changes during puberty depend on gonadal hormones in the slow-developing rodent, Octodon degus. Horm Behav 2011; 60:37-45. [PMID: 21316365 PMCID: PMC3112253 DOI: 10.1016/j.yhbeh.2011.02.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 02/03/2011] [Accepted: 02/03/2011] [Indexed: 11/28/2022]
Abstract
During puberty, human adolescents develop a later chronotype, exhibiting a delay in the timing of rest and activity as well as other daily physiological rhythms. The purpose of this study was to determine whether similar changes in chronotype occur during puberty in a laboratory rodent species, and, if so, to determine whether they are due to pubertal hormones acting on the circadian timekeeping system. To test this hypothesis, we carefully tracked daily activity rhythms across puberty in the slow-developing rodent Octodon degus. We confirmed that male degus showed a large reorganization of activity rhythms that correlated with secondary sex development during puberty, including a loss of bimodality and a 3-5 h phase-advance. Similar to humans, this circadian reorganization showed distinct sex differences, with females showing little change during puberty in two separate experiments. Prepubertal gonadectomy (GDX) eliminated the changes, whereas SHAM gonadectomy had little impact. Therefore, gonadal hormones are likely to play a role in pubertal changes in chronotype in this rodent species. Using evidence from a variety of species, including our recent studies in the rat, we conclude that chronotype changes during puberty are a well-demonstrated phenomenon in mammals.
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Jekl V, Hauptman K, Knotek Z. Diseases in pet degus: a retrospective study in 300 animals. J Small Anim Pract 2011; 52:107-12. [DOI: 10.1111/j.1748-5827.2010.01028.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Hayes LD, Burger JR, Soto-Gamboa M, Sobrero R, Ebensperger LA. Towards an integrative model of sociality in caviomorph rodents. J Mammal 2011; 92:65-77. [PMID: 22328791 PMCID: PMC3277430 DOI: 10.1644/10-mamm-s-039.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study the sociality of caviomorph rodents (New World hystricognaths) before generalizations about rodent sociality could be made. Researchers identified specific problems facing individuals interested in caviomorph sociality, including a lack of information on the proximate mechanisms of sociality, role of social environment in development, and geographical or intraspecific variation in social systems. Since then researchers have described the social systems of many previously understudied species, including some with broad geographical ranges. Researchers have done a good job of determining the role of social environments in development and identifying the costs and benefits of social living. However, relatively little is known about the proximate mechanisms of social behavior and fitness consequences, limiting progress toward the development of integrative (evolutionary-mechanistic) models for sociality. To develop integrative models behavioral ecologists studying caviomorph rodents must generate information on the fitness consequences of different types of social organization, brain mechanisms, and endocrine substrates of sociality. We review our current understanding and future directions for research in these conceptual areas. A greater understanding of disease ecology, particularly in species carrying Old World parasites, is needed before we can identify potential links between social phenotypes, mechanism, and fitness.
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Affiliation(s)
- Loren D. Hayes
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
| | - Joseph Robert Burger
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
- Department of Biology, MSC03 2020/1, University of New Mexico, Albuquerque, NM 87131, USA
| | - Mauricio Soto-Gamboa
- Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Isla teja S/N, Casilla 567, Chile
| | - Raúl Sobrero
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
| | - Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
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Early fitness consequences and hormonal correlates of parental behaviour in the social rodent, Octodon degus. Physiol Behav 2010; 101:509-17. [DOI: 10.1016/j.physbeh.2010.07.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 07/10/2010] [Accepted: 07/27/2010] [Indexed: 11/18/2022]
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31
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Woodruff JA, Lacey EA, Bentley G. Contrasting fecal corticosterone metabolite levels in captive and free-living colonial tuco-tucos (Ctenomys sociabilis). ACTA ACUST UNITED AC 2010; 313:498-507. [DOI: 10.1002/jez.621] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Emery Thompson M, Muller MN, Kahlenberg SM, Wrangham RW. Dynamics of social and energetic stress in wild female chimpanzees. Horm Behav 2010; 58:440-9. [PMID: 20546741 PMCID: PMC3951729 DOI: 10.1016/j.yhbeh.2010.05.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 05/12/2010] [Accepted: 05/17/2010] [Indexed: 11/17/2022]
Abstract
Stress hormone measurements can reinforce and refine hypotheses about the costs of particular contexts or behaviors in wild animals. For social species, this is complicated because potential stressors may come from the physical environment, social environment, or some combination of both, while the stress response itself is generalized. Here, we present a multivariate examination of urinary cortisol dynamics over 6 years in the lives of wild female chimpanzees in the Kanyawara community of Kibale National Park, Uganda. We hypothesized that chimpanzee socioecology provides strong indications of both energetic and social stress to females, but that the salience of these stressors might vary over a female's life history in accordance with their changing reproductive costs and social interactions. Using linear mixed models, we found that urinary cortisol levels increased significantly with age but were also elevated in young immigrants to the community. Across reproductive states, cycling, non-estrous females had relatively low cortisol compared to lactating, estrous, or pregnant females. Aggression from males led to higher cortisol levels among estrous females, frequent targets of aggressive sexual coercion. In contrast, energetic stress was most salient to lactating females, who experienced higher cortisol during months of low fruit consumption. Low dominance rank was associated with increased cortisol, particularly during the energetically demanding period of lactation. The effects of female conflict were felt widely, even among those who were the primary aggressors, providing further evidence that long-term resource competition, while apparently muted, exerts a far-reaching impact on the lives of chimpanzee females.
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Soto-Gamboa M, Gonzalez S, Hayes LD, Ebensperger LA. Validation of a radioimmunoassay for measuring fecal cortisol metabolites in the hystricomorph rodent,Octodon degus. ACTA ACUST UNITED AC 2009; 311:496-503. [DOI: 10.1002/jez.546] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Helmeke C, Ovtscharoff W, Poeggel G, Braun K. Imbalance of immunohistochemically characterized interneuron populations in the adolescent and adult rodent medial prefrontal cortex after repeated exposure to neonatal separation stress. Neuroscience 2008; 152:18-28. [DOI: 10.1016/j.neuroscience.2007.12.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 12/09/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022]
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Romero LM, Meister CJ, Cyr NE, Kenagy GJ, Wingfield JC. Seasonal glucocorticoid responses to capture in wild free-living mammals. Am J Physiol Regul Integr Comp Physiol 2008; 294:R614-22. [DOI: 10.1152/ajpregu.00752.2007] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined baseline and capture-induced glucocorticoid concentrations during two different seasons in three species of wild free-living rodents: brown lemmings ( Lemmus trimucronatus), golden-mantled ground squirrels ( Spermophilus saturatus), and yellow-pine chipmunks ( Tamias amoenus). Initial blood samples were obtained within 3 min of capture, so that initial glucocorticoid levels reflect baseline titers of undisturbed animals. Animals were held for an additional 30 min, when a second blood sample was taken to measure stress-induced glucocorticoid titers. The primary glucocorticoid differed in each species. Lemmings secreted extremely large amounts of corticosterone (as high as 8,000 ng/ml). These high concentrations were accompanied by high corticosterone-binding globulin capacity and resistance to negative feedback. Squirrels and chipmunks secreted a mixture of cortisol and corticosterone (10–400 ng/ml). In males of all three species and female squirrels and chipmunks, glucocorticoid levels were significantly elevated 30 min after capture. Baseline and 30-min glucocorticoid levels differed seasonally in each species. Levels were higher during summer (with no snow cover) than in spring (with ∼60% snow cover) in female lemmings, higher during breeding than before hibernation in squirrels, and higher postreproductively than during breeding in chipmunks. Together, these data indicate that glucocorticoid responses to stress in these free-living species are similar to those in laboratory species, but the magnitude of the response appears to depend on life-history features specific to each species.
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36
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Manire CA, Rasmussen L, Maruska KP, Tricas TC. Sex, seasonal, and stress-related variations in elasmobranch corticosterone concentrations. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:926-35. [DOI: 10.1016/j.cbpa.2007.09.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 09/30/2007] [Accepted: 09/30/2007] [Indexed: 10/22/2022]
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Landys MM, Ramenofsky M, Wingfield JC. Actions of glucocorticoids at a seasonal baseline as compared to stress-related levels in the regulation of periodic life processes. Gen Comp Endocrinol 2006; 148:132-49. [PMID: 16624311 DOI: 10.1016/j.ygcen.2006.02.013] [Citation(s) in RCA: 579] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 01/25/2006] [Accepted: 02/24/2006] [Indexed: 01/01/2023]
Abstract
For decades, demands associated with the predictable life-history cycle have been considered stressful and have not been distinguished from stress that occurs in association with unpredictable and life-threatening perturbations in the environment. The recent emergence of the concept of allostasis distinguishes behavioral and physiological responses to predictable routines as opposed to unpredictable perturbations, and allows for their comparison within one theoretical framework. Glucocorticosteroids (GCs) have been proposed as important mediators of allostasis, as they allow for rapid readjustment and support of behavior and physiology in response to predictable and unpredictable demands (allostatic load). Much work has already been done in defining GC action at the high concentrations that accompany life-threatening perturbations. However, less is known about the role of GCs in relation to daily and seasonal life processes. In this review, we summarize the known behavioral and physiological effects of GCs relating to the predictable life-history cycle, paying particular attention to feeding behavior, locomotor activity and energy metabolism. Although we utilize a comparative approach, emphasis is placed on birds. In addition, we briefly review effects of GCs at stress-related concentrations to test the hypothesis that different levels of GCs play specific and distinct roles in the regulation of life processes and, thus, participate in the promotion of different physiological states. We also examine the receptor types through which GC action may be mediated and suggest mechanisms whereby different GC concentrations may exert their actions. In conclusion, we argue that biological actions of GCs at "non-stress" seasonal concentrations play a critical role in the adjustment of responses that accompany predictable variability in the environment and demand more careful consideration in future studies.
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Affiliation(s)
- Meta M Landys
- Department of Biology, University of Oslo, P.O. Box 1066, Blindern, N-0316 Oslo, Norway.
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38
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Nunes S, Pelz KM, Muecke EM, Holekamp KE, Zucker I. Plasma glucocorticoid concentrations and body mass in ground squirrels: seasonal variation and circannual organization. Gen Comp Endocrinol 2006; 146:136-43. [PMID: 16360155 DOI: 10.1016/j.ygcen.2005.10.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 10/13/2005] [Accepted: 10/17/2005] [Indexed: 10/24/2022]
Abstract
We examined variation in plasma glucocorticoid concentrations of free-living Belding's ground squirrels (Spermophilus beldingi) and captive golden-mantled ground squirrels (Spermophilus lateralis) housed in constant environmental conditions. Plasma corticosterone concentrations were not significantly correlated with time held captive in traps prior to collection of blood samples in males or non-breeding females, but these variables were significantly correlated in breeding females during the pre-mating, lactation, and post-lactation periods. Among male S. beldingi, plasma corticosterone concentrations increased over the course of the active season, and were significantly higher in non-breeding than breeding individuals. Corticosterone concentrations also increased in non-breeding females throughout the active period. In breeding females, baseline (non-stress) corticosterone concentrations, determined from blood samples collected within 3 min of capture, increased during gestation and declined during lactation, whereas stress values of corticosterone, determined from blood samples collected within 4-11 min of capture, increased during gestation and then again during the period after young emerged from the natal burrow. Changes in plasma corticosterone concentrations of S. beldingi paralleled changes in body mass. Among S. lateralis, plasma concentrations of cortisol were elevated when males and females were in reproductive condition and lower in reproductively quiescent squirrels. The annual peak in plasma cortisol concentrations occurred just prior to increases in body mass associated with pre-hibernation fattening. Collectively, these results suggest that concentrations of circulating glucocorticoids fluctuate with circannual rhythmicity in conjunction with annual cycles of change in body mass and activity; within these circannual cycles glucocorticoid concentrations are influenced by stress and breeding status.
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Affiliation(s)
- Scott Nunes
- Department of Biology, University of San Francisco, San Francisco, CA 94117, USA.
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39
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Klose SM, Smith CL, Denzel AJ, Kalko EKV. Reproduction elevates the corticosterone stress response in common fruit bats. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 192:341-50. [PMID: 16273409 DOI: 10.1007/s00359-005-0067-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 08/08/2005] [Accepted: 10/10/2005] [Indexed: 10/25/2022]
Abstract
Changes in reproductive state or the environment may affect the sensitivity of the hypothalamic-pituitary-andrenal (HPA) axis. However, little is known about the dynamics of the resulting corticosteroid stress response, in particular in tropical mammals. In this study, we address the modulation of corticosterone release in response to different reproductive conditions and seasonality in 326 free-living common fruit-eating bats (Artibeus jamaicensis) on Barro Colorado Island in Panama during dry and wet seasons. We present strong evidence that stress sensitivity is primarily modulated by reproductive condition. In reproductively active females, corticosterone increases were more rapid and reached higher levels, but also decreased significantly faster than in inactive females. The corticosterone response was weaker in reproducing males than in females and delayed compared to non-reproductive males. Testes volume in reproductively active males was negatively correlated with corticosterone concentrations. Our findings suggest differentiated dynamics in the corticosterone stress response between sexes, potentially reflecting conflicting ecological demands. In females, a strong acute corticosterone response may represent high stress- and risk-sensitivity that facilitates escape and thus helps to protect reproduction. In males, suppression during reproductive activity could reflect lowered stress sensitivity to avoid chronically elevated corticosterone levels in times of frequent aggressive and therefore costly inter-male encounters.
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Affiliation(s)
- Stefan M Klose
- Ecological Endocrinology Lab, EEL, Department of Experimental Ecology, University of Ulm, Albert Einstein Allee 11, 89069 Ulm, Germany.
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40
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Mohawk JA, Lee TM. Restraint stress delays reentrainment in male and female diurnal and nocturnal rodents. J Biol Rhythms 2005; 20:245-56. [PMID: 15851531 DOI: 10.1177/0748730405276323] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A temporary loss of normal circadian entrainment, such as that associated with shift work and transmeridian travel, can result in an array of detrimental symptoms, making rapid reentrainment of rhythmicity essential. While there is a wealth of literature examining the effects of stress on the entrained circadian system, less is known about the influence of stress on circadian function following a phase shift of the light: dark (LD) cycle. The authors find that recovery of locomotor activity synchronization is altered by restraint stress in the diurnal rodent Octodon degus (degu) and the nocturnal rat. In the first experiment, degus were subjected to a 6-h phase advance of the LD cycle. Sixty minutes after the new lights-on, animals underwent 60 min of restraint stress. The number of days it took each animal to reentrain its activity rhythms to the new LD cycle was recorded and compared to the number of days it took the animal to reentrain under control conditions. When subjected to restraint stress, degus took 30% longer to reentrain their activity rhythms (p < 0.01). In a second experiment, rats underwent a similar experimental paradigm. As with the degus, stress significantly delayed the reentrainment of rats' activity rhythms (p < 0.01). There was no interaction between sex and stress on the rate of reentrainment for either rats or degus. Furthermore, there was no effect of stress on the free-running activity rhythm of degus, suggesting that the effect of stress on reentrainment rate is not secondary to alterations of period length. Together, these data point to a detrimental effect of stress on recovery of entrainment of circadian rhythms, which is independent of activity niche and sex.
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Affiliation(s)
- Jennifer A Mohawk
- Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109-1043, USA
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41
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Ganswindt A, Heistermann M, Hodges K. Physical, Physiological, and Behavioral Correlates of Musth in Captive African Elephants (Loxodonta africana). Physiol Biochem Zool 2005; 78:505-14. [PMID: 15957105 DOI: 10.1086/430237] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 09/15/2004] [Indexed: 11/04/2022]
Abstract
Although musth in male African elephants (Loxodonta africana) is known to be associated with increased aggressiveness, urine dribbling (UD), temporal gland secretion (TGS), and elevated androgens, the temporal relationship between these changes has not been examined. Here, we describe the pattern of musth-related characteristics in 14 captive elephant bulls by combining long-term observations of physical and behavioral changes with physiological data on testicular and adrenal function. The length of musth periods was highly variable but according to our data set not related to age. Our data also confirm that musth is associated with elevated androgens and, in this respect, show that TGS and UD are downstream effects of this elevation, with TGS responding earlier and to lower androgen levels than UD. Because the majority of musth periods were associated with a decrease in glucocorticoid levels, our data also indicate that musth does not represent a physiological stress mediated by the hypothalamic-pituitary-adrenal axis. Furthermore, we demonstrate that the occurrence of musth is associated with increased aggression and that this is presumably androgen mediated because aggressive males had higher androgen levels. Collectively, the information generated contributes to a better understanding of what characterizes and initiates musth in captive African elephants and provides a basis for further studies designed to examine in more detail the factors regulating the intensity and duration of musth.
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Affiliation(s)
- Andre Ganswindt
- Department of Reproductive Biology, German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany.
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42
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Reeder DM, Kramer KM. STRESS IN FREE-RANGING MAMMALS: INTEGRATING PHYSIOLOGY, ECOLOGY, AND NATURAL HISTORY. J Mammal 2005. [DOI: 10.1644/bhe-003.1] [Citation(s) in RCA: 299] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Soto-Gamboa M, Villalón M, Bozinovic F. Social cues and hormone levels in male Octodon degus (Rodentia): a field test of the Challenge Hypothesis. Horm Behav 2005; 47:311-8. [PMID: 15708760 DOI: 10.1016/j.yhbeh.2004.11.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2004] [Revised: 10/28/2004] [Accepted: 11/01/2004] [Indexed: 11/20/2022]
Abstract
Social interactions are important factors determining and regulating individual behaviors. Testosterone has been related to agonistic interactions, while glucocorticoids have been related to social stress, especially during interactions of dominance. We compared testosterone and cortisol concentrations in male degus (Octodon degus, Rodentia) under laboratory conditions without male social interactions, with data from wild males in nature. Under natural conditions, males should present higher levels of testosterone during the breeding season due to social interactions (Challenge Hypothesis). Alternatively, intense social instability could act as a stressing environment, raising glucocorticoids, which inhibit testosterone concentrations. Our results show a significant increase in agonistic interactions between males during the breeding season, and disappearance of non-agonistic male interactions during this period. Hormone levels in breeding season show nonsignificant differences between laboratory groups, but testosterone concentrations in field males were significantly higher than in laboratory males. Testosterone levels were similar among pre-breeding and breeding periods, but in field animals the concentration was approximately 30% higher than in laboratory degus. In field animals, we found two different mating strategies: resident males, with territorial behavior, and transient males, displayed an opportunistic approach to females. Finally, cortisol presents a similar pattern in both laboratory and field animals; pre-breeding values of cortisol are higher than during the breeding season. This suggests that social interactions in O. degus activate a rise in testosterone, supporting the Challenge Hypothesis, and could be considered as partial support of the Social Stress Hypothesis.
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Affiliation(s)
- Mauricio Soto-Gamboa
- Instituto de Zoología, Facultad de Ciencias, Universidad Austral de Chile, Casilla (Box) 567, Valdivia, Chile.
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44
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Ganswindt A, Rasmussen HB, Heistermann M, Hodges JK. The sexually active states of free-ranging male African elephants (Loxodonta africana): defining musth and non-musth using endocrinology, physical signals, and behavior. Horm Behav 2005; 47:83-91. [PMID: 15579269 DOI: 10.1016/j.yhbeh.2004.09.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Revised: 06/10/2004] [Accepted: 09/13/2004] [Indexed: 11/20/2022]
Abstract
Musth in male African elephants, Loxodonta africana, is associated with increased aggressive behavior, continuous discharge of urine, copious secretions from the swollen temporal glands, and elevated androgen levels. During musth, bulls actively seek out and are preferred by estrous females although sexual activity is not restricted to the musth condition. The present study combines recently established methods of fecal hormone analysis with long-term observations on male-female associations as well as the presence and intensity of physical signals to provide a more detailed picture about the physical, physiological, and behavioral characteristics of different states of sexual activity in free-ranging African elephants. Based on quantitative shifts in individual bull association patterns, the presence of different physical signals, and significant differences in androgen levels, a total of three potential sub-categories for sexually active bulls could be established. The results demonstrate that elevations in androgen levels are only observed in sexually active animals showing temporal gland secretion and/or urine dribbling, but are not related to the age of the individual. Further, none of the sexually active states showed elevated glucocorticoid output indicating that musth does not represent an HPA-mediated stress condition. On the basis of these results, we suggest that the term "musth" should be exclusively used for the competitive state in sexually active male elephants and that the presence of urine dribbling should be the physical signal used for defining this state.
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Affiliation(s)
- André Ganswindt
- Department of Reproductive Biology, German Primate Centre, 37077 Göttingen, Germany.
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45
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Mohawk JA, Cashen K, Lee TM. Inhibiting cortisol response accelerates recovery from a photic phase shift. Am J Physiol Regul Integr Comp Physiol 2004; 288:R221-8. [PMID: 15331380 DOI: 10.1152/ajpregu.00272.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Jetlag results when a temporary loss of circadian entrainment alters phase relationships among internal rhythms and between an organism and the outside world. After a large shift in the light-dark (LD) cycle, rapid recovery of entrainment minimizes the negative effects of internal circadian disorganization. There is evidence in the existing literature for an activation of the hypothalamic-pituitary-adrenal (HPA) axis after a photic phase shift, and it is possible that the degree of HPA-axis response is a determining factor of reentrainment time. This study utilized a diurnal rodent, Octodon degus, to test the prediction that the alteration of cortisol levels would affect the reentrainment rate of circadian locomotor rhythms. In experiment 1, we examined the effects of decreased cortisol (using metyrapone, an 11beta-hydroxylase inhibitor) on the rate of running-wheel rhythm recovery after a 6-h photic phase advance. Metyrapone treatment significantly shortened the length of time it took animals to entrain to the new LD cycle (11.5% acceleration). In experiment 2, we examined the effects of increased cortisol on the rate of reentrainment after a 6-h photic phase advance. Increasing plasma cortisol levels increased the number of days (8%) animals took to reentrain running-wheel activity rhythms, but this effect did not reach significance. A third experiment replicated the results of experiment 1 and also demonstrated that suppression of HPA activity via dexamethasone injection is capable of accelerating reentrainment rates by approximately 33%. These studies provide support for an interaction between the stress axis and circadian rhythms in determining the rate of recovery from a phase shift of the LD cycle.
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Affiliation(s)
- Jennifer A Mohawk
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA
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46
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Poeggel G, Helmeke C, Abraham A, Schwabe T, Friedrich P, Braun K. Juvenile emotional experience alters synaptic composition in the rodent cortex, hippocampus, and lateral amygdala. Proc Natl Acad Sci U S A 2003; 100:16137-42. [PMID: 14668442 PMCID: PMC307705 DOI: 10.1073/pnas.2434663100] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Accepted: 10/10/2003] [Indexed: 11/18/2022] Open
Abstract
A quantitative anatomical study in the rodent anterior cingulate and somatosensory cortex, hippocampus, and lateral amygdala revealed region-, cell-, and dendrite-specific changes of spine densities in 3-week-old Octodon degus after repeated parental separation. In parentally separated animals significantly higher spine densities were found on the apical and basal dendrites of the cingulate cortex (up to 143% on apical and 138% on basal dendrite). Branching order analysis revealed that this effect is seen on all segments of the apical dendrite, whereas on the basal dendrites significantly higher spine densities were seen only on the outer branches (third to fifth dendritic segments). Increased spine densities were also observed on the hippocampal CA1 pyramidal neurons (up to 109% on the distal apical segments and up to 106% on the basal segment) compared with the control group. In contrast, significantly reduced spine densities were observed on the granule cell dendrites in the dentate gyrus (down to 92%) and on the apical dendrites in the medial nucleus of the amygdala (down to 95%). No significant changes of spine densities were seen in the somatosensory cortex (except for an increase in the proximal apical segments) and in the lateral nucleus of the dorsal amygdala (except for an increase in the proximal basal dendritic segments). These results demonstrate that repeated stressful emotional experience alters the balance of presumably excitatory synaptic inputs of pyramidal neurons in the limbic system. Such experience-induced modulations of limbic circuits may determine psychosocial and cognitive capacities during later life.
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Affiliation(s)
- Gerd Poeggel
- Department of Human Biology, University of Leipzig, Talstrasse 35, 04103 Leipzig, Germany
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47
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Rogovin KO, Randall JA, Kolosova I, Moshkin M. Social correlates of stress in adult males of the great gerbil, Rhombomys opimus, in years of high and low population densities. Horm Behav 2003; 43:132-9. [PMID: 12614643 DOI: 10.1016/s0018-506x(02)00028-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The great gerbil, Rhombomys opimus, is the most social species in the Gerbillinae. The social structure consists of family groups that occupy isolated systems of burrows consisting of one breeding male, from one to seven females, and juveniles. During a year of peak density and one of density decline, we studied the influence of group size, group composition, local density, and distance to the nearest groups on fecal corticosterone and testosterone concentrations in breeding males. We also examined the relationship of hormone concentrations to the survival of males during the summer drought between the spring and the fall. We found that males differed in concentrations of steroid hormones. Concentrations of testosterone were lower whereas those of corticosterone tended to be higher in a year of high population densities compared with higher testosterone and lower corticosterone in a year with a lower density. This finding suggests that stress may be greater in higher densities because of increased social contact. Stepwise regression analysis revealed a positive and significant influence of the number of adult females in a family group on concentrations of fecal corticosterone and testosterone in adult males. Concentrations of corticosterone were also significantly higher in males that disappeared from family groups between the spring and the fall compared with males still alive in family groups in the fall. There was no change in concentrations of testosterone. These results suggest that social interactions within large family groups may be an important source of stress for adult males.
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Abstract
The vertebrate stress response helps animals respond to environmental dangers such as predators or storms. An important component of the stress response is glucocorticoid (GC) release, resulting from activation of the hypothalamic-pituitary-adrenal axis. After release, GCs induce a variety of behavioral and physiological changes that presumably help the animal respond appropriately to the situation. Consequently, GC secretion is often considered an obligatory response to stressful situations. Evidence now indicates, however, that free-living species from many taxa can seasonally modulate GC release. In other words, the magnitudes of both unstressed and stressed GC concentrations change depending upon the time of year. This review examines the growing evidence that GC concentrations in free-living reptiles, amphibians, and birds, but not mammals, are commonly elevated during the breeding season. This evidence is then used to test three hypotheses with different focuses on GC's energetic or behavioral effects, as well as on GC's role in preparing the animal for subsequent stressors. These hypotheses attempt to place annual GC rhythms into a physiological or behavioral context. Integrating seasonal differences in GC concentrations with either different physiological states or different life history stages provides clues to a new understanding of how GCs actually help in survival during stress. Consequently, understanding seasonal modulation of GC release has far-reaching importance for both the physiology of the stress response and the short-term survival of individual animals.
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Affiliation(s)
- L Michael Romero
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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49
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Goymann W, East ML, Wachter B, Höner OP, Möstl E, Van't Hof TJ, Hofer H. Social, state-dependent and environmental modulation of faecal corticosteroid levels in free-ranging female spotted hyenas. Proc Biol Sci 2001; 268:2453-9. [PMID: 11747563 PMCID: PMC1088899 DOI: 10.1098/rspb.2001.1828] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Little is known about to what extent the sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis may be state dependent and vary in the same species between environments. Here we tested whether the faecal corticosteroid concentrations of matrilineal adult female spotted hyenas are influenced by social and reproductive status in adjacent ecosystems and whether they vary between periods with and without social stress. Females in the Serengeti National Park frequently become socially subordinate intruders in other hyena territories by undertaking long-distance foraging trips to migratory herds, whereas in the Ngorongoro Crater they usually forage inside their own small territories on resident prey. The faecal corticosteroid concentrations in Serengeti females were significantly higher than in Ngorongoro females. Energy expenditure by lactation is exceptionally high in spotted hyenas and this may be reflected in their corticosteroid levels. The faecal corticosteroid levels in both populations were higher in lactating than in non-lactating females. During periods of social stability, faecal corticosteroid concentrations increased in non-lactating females but not in lactating females as social status declined. Lactating Serengeti females had significantly higher faecal corticosteroid concentrations during periods with acute severe social stress than during periods without, indicating that the HPA axis is sensitive to social stimuli even in lactating females. So far few studies have used non-invasive monitoring methods for assessing social stress in freeranging animals. This study demonstrates for the first time, to the authors' knowledge, that corticosteroid concentrations may differ between periods with and without social stress for a free-ranging female mammal and that the modulating effect of social status may depend on reproductive status.
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Affiliation(s)
- W Goymann
- Max-Planck-Institute for Behavioural Physiology, D-82319 Seewiesen Post Starnberg, Germany.
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50
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Harper JM, Austad SN. Effect of capture and season on fecal glucocorticoid levels in deer mice (Peromyscus maniculatus) and red-backed voles (Clethrionomys gapperi). Gen Comp Endocrinol 2001; 123:337-44. [PMID: 11589634 DOI: 10.1006/gcen.2001.7682] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of confinement and season on fecal glucocorticoid (GC) levels in deer mice (Peromyscus maniculatus) and red-backed voles (Clethrionomys gapperi) was determined. Deer mice confined in a Sherman trap more than 4 h had fecal GC levels that were significantly higher than those in individuals that remained in a trap 4 h or less. However, this treatment may not be stressful for red-backed voles as neither plasma nor fecal GC levels were significantly elevated after 12 h of confinement. In addition, a clear temporal pattern in the secretion of fecal GCs was observed between mid June and early November in both species.
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Affiliation(s)
- J M Harper
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844, USA.
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