Validation of a radioimmunoassay for measuring testosterone concentrations in plasma samples of the subterranean rodent Ctenomys talarum: outstandingly elevated levels in the wild and the effect of captivity.

We validated the Coat-a-Count radioimmunoassay (RIA) kit for measuring testosterone in plasma samples of the subterranean rodent Ctenomys talarum and evaluated testosterone levels in free-living and captive individuals. The performance of the assay was evaluated by the assessment of parallelism, accuracy and precision. Moreover, the high specificity of the assay antibody was confirmed by high-pressure liquid chromatography with ultraviolet detector, followed by electrospray ionization tandem mass spectrometry. Results indicated that plasma samples have to be treated with heat and diluted before the RIA for the optimization of the assay. Plasma testosterone concentrations in free-living animals were outstandingly elevated (up to 329 ng/mL), which are among the highest ever reported for mammals. On the other hand, captivity produced a 14-fold decrease in plasma testosterone concentrations, emphasizing that very significant changes in the endocrine milieu may occur in wild animals kept under laboratory conditions. Our results place tuco-tucos as an interesting model for the study of androgen regulation in mammals, suggesting that target tissues may have low sensitivity to the testosterone signal and agree with a scenario of elevated levels of sex hormone-binding globulin in plasma.

[1]  M. Shemesh,et al.  Changes in plasma testosterone levels during the annual reproductive cycle of the hibernating bat, Myotis lucifugus lucifugus with a survey of plasma testosterone levels in adult male vertebrates. , 1976, Biology of reproduction.

[2]  R. W. Kuhn,et al.  The serum transport of steroid hormones. , 1982, Recent progress in hormone research.

[3]  J. Hodges,et al.  Sex steroids and their relationship to binding proteins in the serum of the marmoset monkey (Callithrix jacchus). , 1983, The Journal of endocrinology.

[4]  J. Wingfield,et al.  Physiologic properties of steroid hormone-binding proteins in avian blood. , 1984, General and comparative endocrinology.

[5]  I. McDonald,et al.  Failure of glucocorticoid feedback in males of a population of small marsupials (Antechinus swainsonii) during the period of mating. , 1986, The Journal of endocrinology.

[6]  E. Slaats,et al.  Interference of sex-hormone binding globulin in the "Coat-A-Count" testosterone no-extraction radioimmunoassay. , 1987, Clinical chemistry.

[7]  P. Stein,et al.  Hormone binding globulins undergo serpin conformational change in inflammation , 1988, Nature.

[8]  M. Dowsett,et al.  Three methods compared for estimating the fraction of testosterone and estradiol not bound to sex-hormone-binding globulin. , 1989, Clinical chemistry.

[9]  C. Busch,et al.  Spatial distribution and attributes of a population of Ctenomys talarum (Rodentia: Octodontidae) , 1989 .

[10]  R. Hähnel,et al.  Investigation of sex-hormone binding globulin interference in direct radioimmunoassays for testosterone and estradiol. , 1989, Clinical chemistry.

[11]  C. Busch,et al.  An overview of evolution, systematics, population biology, cytogenetics, molecular biology and speciation in Ctenomys. , 1990, Progress in clinical and biological research.

[12]  J. Wingfield,et al.  The "Challenge Hypothesis": Theoretical Implications for Patterns of Testosterone Secretion, Mating Systems, and Breeding Strategies , 1990, The American Naturalist.

[13]  W. Rosner,et al.  The functions of corticosteroid-binding globulin and sex hormone-binding globulin: recent advances. , 1990, Endocrine reviews.

[14]  C. Busch,et al.  Reproductive parameters and growth in the fossorial rodent Ctenomys talarum (Rodentia: Octodontidae) , 1991 .

[15]  A. Bradley,et al.  Testosterone levels in the Tasmanian bettong (Bettongia gaimardi). , 1991, General and comparative endocrinology.

[16]  D. Wildt,et al.  Monitoring ovarian function and pregnancy by evaluating excretion of urinary oestrogen conjugates in semi-free-ranging Przewalski's horses (Equus przewalskii). , 1991, Journal of reproduction and fertility.

[17]  C. Busch,et al.  Burrow structure in the subterranean rodent Ctenomys talarum , 1992 .

[18]  W. Zielinski,et al.  Testosterone and competitive ability in male house mice, Mus musculus: laboratory and field studies , 1993, Animal Behaviour.

[19]  S. Wasser,et al.  Excretion rates and metabolites of oestradiol and progesterone in baboon (Papio cynocephalus cynocephalus) faeces. , 1994, Journal of reproduction and fertility.

[20]  Wong Yn,et al.  Analysis of corticosterone in rat plasma by high-performance liquid chromatography. , 1994 .

[21]  B. Chien,et al.  Analysis of corticosterone in rat plasma by high-performance liquid chromatography. , 1994, Journal of chromatography. B, Biomedical applications.

[22]  G. Read,et al.  Oestradiol measurement in women on oral hormone replacement therapy: the validity of commercial test kits. , 1995, British journal of biomedical science.

[23]  M. Zuk,et al.  Sex differences in parasite infections: patterns and processes. , 1996, International journal for parasitology.

[24]  David A. Enstrom,et al.  Testosterone and mate choice in the dark-eyed junco , 1997, Animal Behaviour.

[25]  G. Chrousos,et al.  The hypothalamic-pituitary-adrenal axis of prairie voles (Microtus ochrogaster): evidence for target tissue glucocorticoid resistance. , 1997, General and comparative endocrinology.

[26]  S. Wasser,et al.  Steroid metabolism and validation of noninvasive endocrine monitoring in the African wild dog (Lycaon pictus) , 1997 .

[27]  P. Jewell.  Survival and behaviour of castrated Soay sheep (Ovis aries) in a feral island population on Hirta, St. Kilda, Scotland , 1997 .

[28]  J. Tesarik,et al.  Nongenomic actions of steroid hormones in reproductive tissues. , 1998, Endocrine reviews.

[29]  S. Wasser,et al.  Longitudinal fecal steroid excretion in maned wolves (Chrysocyon brachyurus). , 1998, General and comparative endocrinology.

[30]  Brian M. Barnes,et al.  Annual Cycle of Body Composition and Hibernation in Free-Living Arctic Ground Squirrels , 1999 .

[31]  R. Zenuto,et al.  DNA fingerprinting reveals polygyny in the subterranean rodent Ctenomys talarum , 1999, Molecular ecology.

[32]  C. Selby,et al.  Interference in Immunoassay , 1999, Annals of clinical biochemistry.

[33]  I. Clarke,et al.  Effects of stress on reproduction in non-rodent mammals: the role of glucocorticoids and sex differences. , 2000, Reviews of reproduction.

[34]  Barry Sinervo,et al.  Testosterone, Endurance, and Darwinian Fitness: Natural and Sexual Selection on the Physiological Bases of Alternative Male Behaviors in Side-Blotched Lizards , 2000, Hormones and Behavior.

[35]  J. Terkel,et al.  Urinary testosterone levels in the male blind mole rat (Spalax ehrenbergi) affect female preference , 2000, Physiology & Behavior.

[36]  N. Place,et al.  Seasonal changes in plasma testosterone and glucocorticosteroids in free-living male yellow-pine chipmunks and the response to capture and handling , 2000, Journal of Comparative Physiology B.

[37]  Michael E. Pereira,et al.  Mating Season Aggression and Fecal Testosterone Levels in Male Ring-Tailed Lemurs (Lemur catta) , 2000, Hormones and Behavior.

[38]  E. Falkenstein,et al.  Multiple actions of steroid hormones--a focus on rapid, nongenomic effects. , 2000, Pharmacological reviews.

[39]  P. Deviche,et al.  Testosterone, corticosterone, and photoperiod interact to regulate plasma levels of binding globulin and free steroid hormone in dark-eyed juncos, Junco hyemalis. , 2001, General and comparative endocrinology.

[40]  H. Hofer,et al.  Androgens and the Role of Female “Hyperaggressiveness” in Spotted Hyenas (Crocuta crocuta) , 2001, Hormones and Behavior.

[41]  G. Visser,et al.  Energy expenditure and testosterone in free-living male yellow-pine chipmunks. , 2002, The Journal of experimental zoology.

[42]  John H. Schulz,et al.  USING A COMMERCIALLY AVAILABLE RADIOIMMUNOASSAY TO QUANTIFY CORTICOSTERONE IN AVIAN PLASMA , 2002 .

[43]  A. I. Vassallo,et al.  Comportamiento social y reproductivo del roedor subterráneo solitario Ctenomys talarum (Rodentia: Ctenomyidae) en condiciones de semicautiverio , 2002 .

[44]  C. Breuner,et al.  Plasma binding proteins as mediators of corticosteroid action in vertebrates. , 2002, The Journal of endocrinology.

[45]  D. O'Kane,et al.  Phantoms in the assay tube: heterophile antibody interferences in serum thyroglobulin assays. , 2003, The Journal of clinical endocrinology and metabolism.

[46]  J. Wingfield,et al.  Reproduction and Resistance to Stress: When and How , 2003, Journal of neuroendocrinology.

[47]  J. Velázquez-Moctezuma,et al.  Changes in masculine sexual behavior, corticosterone and testosterone in response to acute and chronic stress in male rats , 2003, Hormones and Behavior.

[48]  K. Yuen,et al.  Determination of plasma testosterone using a simple liquid chromatographic method. , 2003, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[49]  J. Toppari,et al.  Serum androgen bioactivity in cryptorchid and noncryptorchid boys during the postnatal reproductive hormone surge. , 2003, The Journal of clinical endocrinology and metabolism.

[50]  F. Tanrıverdi,et al.  The hypothalamic-pituitary-gonadal axis: immune function and autoimmunity. , 2003, The Journal of endocrinology.

[51]  Greg Ward,et al.  Interferences in immunoassay. , 2004, The Clinical biochemist. Reviews.

[52]  R. Boonstra.  EQUIPPED FOR LIFE: THE ADAPTIVE ROLE OF THE STRESS AXIS IN MALE MAMMALS , 2005 .

[53]  J. M. Busso,et al.  Assessment of urine and fecal testosterone metabolite excretion in Chinchilla lanigera males. , 2005, Animal reproduction science.

[54]  Mauricio Soto Gamboa.  Free and total testosterone levels in field males of Octodon degus (Rodentia, Octodontidae): accuracy of the hormonal regulation of behavior , 2005 .

[55]  C. Marler,et al.  Winning fights elevates testosterone levels in California mice and enhances future ability to win fights , 2005, Hormones and Behavior.

[56]  M. Soto-Gamboa,et al.  Social cues and hormone levels in male Octodon degus (Rodentia): a field test of the Challenge Hypothesis , 2005, Hormones and Behavior.

[57]  J. Simard,et al.  Is dehydroepiandrosterone a hormone? , 2005, The Journal of endocrinology.

[58]  D. Lichtermann,et al.  Plasma testosterone and sexual function in men receiving buprenorphine maintenance for opioid dependence. , 2005, The Journal of clinical endocrinology and metabolism.

[59]  K. Gross,et al.  Glucocorticoid resistance in squirrel monkeys results from a combination of a transcriptionally incompetent glucocorticoid receptor and overexpression of the glucocorticoid receptor co-chaperone FKBP51 , 2006, The Journal of Steroid Biochemistry and Molecular Biology.

[60]  C. RaquelCepeda,et al.  Variaciones Morfométricas de la Próstata de Chinchilla laniger (MOLINA, 1982) y de la Concentración de Testosterona Plasmática Durante un Ciclo Reproductivo Anual , 2006 .

[61]  T. Hahn,et al.  Development of stress reactivity in white-crowned sparrow nestlings: total corticosterone response increases with age, while free corticosterone response remains low. , 2007, General and comparative endocrinology.

[62]  T. Williams,et al.  Individual variation in endocrine systems: moving beyond the ‘tyranny of the Golden Mean’ , 2008, Philosophical Transactions of the Royal Society B: Biological Sciences.

[63]  Energy Budget in Subterranean Rodents: Insights from the Tuco-Tuco Ctenomys Talarum (Rodentia: Ctenomyidae)El Presupuesto EnergÉTico En Roedores SubterrÁNeos A La Luz De Estudios En El Tuco-Tuco Ctenomys Talarum (Rodentia: Ctenomyodae) , 2007 .

[64]  C. D. Antinuchi,et al.  Energetics and thermoregulation during digging in the rodent tuco-tuco (Ctenomys talarum). , 2007, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[65]  R. Zenuto,et al.  Familiarity and mating behavior in the subterranean rodent Ctenomys talarum (tuco-tuco) , 2007 .

[66]  P. Kappeler,et al.  Androgen and glucocorticoid levels reflect seasonally occurring social challenges in male redfronted lemurs (Eulemur fulvus rufus) , 2007, Behavioral Ecology and Sociobiology.

[67]  J. M. Busso,et al.  Noninvasive monitoring of ovarian endocrine activity in the chinchilla (Chinchilla lanigera). , 2007 .

[68]  K. Gross,et al.  Androgen resistance in squirrel monkeys (Saimiri spp.). , 2008, Comparative medicine.

[69]  F. Vera,et al.  Decreased glucose tolerance but normal blood glucose levels in the field in the caviomorph rodent Ctenomys talarum: the role of stress and physical activity. , 2008, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[70]  A. K. Davis,et al.  The use of leukocyte profiles to measure stress in vertebrates: a review for ecologists , 2008 .

[71]  B. Wallner,et al.  Conflict-involvement of male guinea pigs (Cavia aperea f. porcellus) as a criterion for partner preference , 2008, Behavioral Ecology and Sociobiology.

[72]  Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis). , 2008, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[73]  A. Newman,et al.  Dehydroepiandrosterone and corticosterone are regulated by season and acute stress in a wild songbird: jugular versus brachial plasma. , 2008, Endocrinology.

[74]  C. Schradin.  Seasonal changes in testosterone and corticosterone levels in four social classes of a desert dwelling sociable rodent , 2008, Hormones and Behavior.

[75]  R. Zenuto,et al.  Copulatory pattern of the subterranean rodent Ctenomys talarum , 2008 .

[76]  K. Wynne-Edwards,et al.  Analysis of steroids in songbird plasma and brain by coupling solid phase extraction to radioimmunoassay. , 2008, General and comparative endocrinology.

[77]  A. Bradley,et al.  Plasma DHEA levels in wild, territorial red squirrels: seasonal variation and effect of ACTH. , 2008, General and comparative endocrinology.

[78]  J. Wingfield,et al.  Seasonal glucocorticoid responses to capture in wild free-living mammals. , 2008, American journal of physiology. Regulatory, integrative and comparative physiology.

[79]  Rebecca M. Calisi,et al.  Lab and field experiments: Are they the same animal? , 2009, Hormones and Behavior.

[80]  M. Soto-Gamboa,et al.  Validation of a radioimmunoassay for measuring fecal cortisol metabolites in the hystricomorph rodent, Octodon degus. , 2009, Journal of experimental zoology. Part A, Ecological genetics and physiology.

[81]  R. Zenuto,et al.  Effect of diet quality and soil hardness on metabolic rate in the subterranean rodent Ctenomys talarum. , 2009, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[82]  R. Zenuto.  Dear enemy relationships in the subterranean rodent Ctenomys talarum: the role of memory of familiar odours , 2010, Animal Behaviour.

[83]  R. Zenuto,et al.  Seasonality of breeding in wild tuco-tucosCtenomys talarum in relation to climate and food availability , 2006, Acta Theriologica.

[84]  R. Zenuto,et al.  Mounting a specific immune response increases energy expenditure of the subterranean rodent Ctenomys talarum (tuco-tuco): implications for intraspecific and interspecific variation in immunological traits , 2010, Journal of Experimental Biology.

[85]  F. Vera,et al.  Cortisol and corticosterone exhibit different seasonal variation and responses to acute stress and captivity in tuco-tucos (Ctenomys talarum). , 2011, General and comparative endocrinology.