The effects of terrestrial and breeding densities on corticosterone and testosterone levels in spotted salamanders, Ambystoma maculatum

2004 ◽  
Vol 82 (11) ◽  
pp. 1795-1803 ◽  
Author(s):  
Mark D Cooperman ◽  
J Michael Reed ◽  
L Michael Romero
Keyword(s):  
Plasma Concentrations ◽  
High Density ◽  
Ambystoma Maculatum ◽  
Plasma Testosterone ◽  
Adult Density ◽  
Free Living ◽  
Testosterone Levels ◽  
Potential Competition

We examined plasma concentrations of corticosterone (CORT) and testosterone in male free-living and captive spotted salamanders, Ambystoma maculatum (Shaw, 1802), to determine if (i) they mounted significant CORT responses to conspecifics in captive enclosures during potential competition for limited burrows; (ii) artificially induced, increased breeding densities altered CORT and testosterone levels in a free-living population; and (iii) testosterone in free-living males varied seasonally. We found increased baseline CORT in captive male spotted salamanders exposed to conspecifics under high densities (4 animals with only 1 burrow). Original residents of the cage, however, had significantly higher baseline CORT titers than did newly introduced animals, and titers were significantly higher in animals cohabiting a burrow than those remaining outside the burrow. This suggests that spotted salamanders perceive con specifics as threats for burrows and become stressed when forced to share these resources. In contrast, free-living spotted salamanders during breeding showed no significant increases in baseline CORT or testosterone in high-density treatments. This suggests that increased adult density during breeding is not stressful to these salamanders. Finally, spotted salamanders had greater plasma testosterone titers in fall than in spring, suggesting that they are dissociated breeders.

INFLUENCE OF METYRAPONE ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND ANDROSTENEDIONE IN MAN

1971 ◽  
Vol 68 (3) ◽  
pp. 576-584 ◽  
Author(s):  
K. O. Nilsson ◽  
B. Hökfelt
Keyword(s):  
Body Weight ◽  
Male Patient ◽  
Gradual Increase ◽  
Plasma Concentrations ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Basal Plasma ◽  
Normal Males ◽  
A Minor ◽  
Secondary Hypogonadism

ABSTRACT Metyrapone was administered either orally, 750 mg every four h, in a total of six doses, or intravenously 30 mg per kg body weight as a four h infusion. In three males with normal endocrine functions, metyrapone given orally or intravenously induced a fall in plasma testosterone and an elevation of androstenedione within 2–8 h. When metyrapone was administered to a patient given dexamethasone to suppress endogenous ACTH production, the androstenedione levels did not alter whereas the testosterone levels showed a slight, transient decrease. In two normal females metyrapone administration was followed by a marked increase in plasma androstenedione whereas testosterone showed only a minor, gradual increase. In one male patient with Addison's disease the basal plasma testosterone was normal whereas the level of androstenedione was low. Following metyrapone intravenously, there was a slight suppression of plasma testosterone but no change in the androstenedione concentration. In one patient with primary hypogonadism, two with secondary hypogonadism and two with Klinefelter's syndrome the plasma testosterone was low under basal conditions and did not change following metyrapone. Basal plasma androstenedione was within the range for normal males and increased markedly following metyrapone in all the cases.

Inter-annual repeatability and age-dependent changes in plasma testosterone levels in a longitudinally monitored free-living passerine bird

Oecologia ◽  
2021 ◽  
Author(s):  
Martin Těšický ◽  
Tereza Krajzingrová ◽  
Jiří Eliáš ◽  
Hana Velová ◽  
Jana Svobodová ◽  
...  
Keyword(s):  
Passerine Bird ◽  
Plasma Testosterone ◽  
Free Living ◽  
Testosterone Levels ◽  
Age Dependent

Endocrine correlates of territoriality, breeding stage, and body molt in free-living willow ptarmigan of both sexes

1990 ◽  
Vol 68 (10) ◽  
pp. 2130-2134 ◽  
Author(s):  
Susan J. Hannon ◽  
John C. Wingfield
Keyword(s):  
Luteinizing Hormone ◽  
Aggressive Behaviour ◽  
Follicle Stimulating Hormone ◽  
Plasma Concentrations ◽  
Egg Laying ◽  
Plasma Testosterone ◽  
Willow Ptarmigan ◽  
Free Living ◽  
Brood Rearing ◽  
Egg Formation

Concentrations of plasma testosterone, estradiol, corticosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured by radioimmunoassay in wild willow ptarmigan (Lagopus lagopus) of both sexes over the breeding season. In males, plasma concentrations of testosterone and LH increased once they became territorial, and this was paralleled by increases in comb size and initiation of molt into courtship plumage. A decline of testosterone and circulating LH levels during late territoriality and egg laying coincided with molt into summer plumage. FSH titers did not vary significantly through the season, but there was a trend for higher levels during the territorial period. Plasma concentrations of corticosterone were highest during pre- and late territoriality and brood rearing. In females, testosterone levels were about 13 times lower than in males and did not vary significantly, whereas LH was high from pre- to mid-territoriality and again in the brood season. Elevated LH levels may be correlated with aggressive behaviour in females. FSH and estradiol concentrations were highest during the period of egg formation. Corticosterone was correlated with chase time in both sexes.

scholarly journals Neuroendocrine patterns underlying seasonal song and year-round territoriality in male black redstarts

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Camila P. Villavicencio ◽  
Harriet Windley ◽  
Pietro B. D’Amelio ◽  
Manfred Gahr ◽  
Wolfgang Goymann ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Life Cycle ◽  
Receptor Expression ◽  
Territorial Behavior ◽  
Plasma Testosterone ◽  
Estrogen Receptor Expression ◽  
Free Living ◽  
Testosterone Levels ◽  
Life Cycle Stages ◽  
Song Control

Abstract Background The connection between testosterone and territoriality in free-living songbirds has been well studied in a reproductive context, but less so outside the breeding season. To assess the effects of seasonal androgenic action on territorial behavior, we analyzed vocal and non-vocal territorial behavior in response to simulated territorial intrusions (STIs) during three life-cycle stages in free-living male black redstarts: breeding, molt and nonbreeding. Concurrently, we measured changes in circulating testosterone levels, as well as the mRNA expression of androgen and estrogen receptors and aromatase in the preoptic, hypothalamic and song control brain areas that are associated with social and vocal behaviors. Results Territorial behavior and estrogen receptor expression in hypothalamic areas did not differ between stages. But plasma testosterone was higher during breeding than during the other stages, similar to androgen receptor and aromatase expression in the preoptic area. The expression of androgen receptors in the song control nucleus HVC was lower during molt when birds do not sing or sing rarely, but similar between the breeding and the nonbreeding stage. Nevertheless, some song spectral features and the song repertoire differed between breeding and nonbreeding. Territorial behavior and song rate correlated with the expression of steroid receptors in hypothalamic areas, and in the song control nucleus lMAN. Conclusions Our results demonstrate seasonal modulation of song, circulating testosterone levels, and brain sensitivity to androgens, but a year-round persistency of territorial behavior and estrogen receptor expression in all life-cycle stages. This suggests that seasonal variations in circulating testosterone concentrations and brain sensitivity to androgens is widely uncoupled from territorial behavior and song activity but might still affect song pattern. Our study contributes to the understanding of the complex comparative neuroendocrinology of song birds in the wild.

Circulating steroid hormones in prostate carcinogenesis. Part 1 – Androgens

2010 ◽  
Vol 3 (1) ◽  
Author(s):  
Jean Fiet ◽  
Frank Giton
Keyword(s):  
Plasma Concentrations ◽  
Case Control ◽  
Epidemiologic Studies ◽  
Sex Hormone Binding Globulin ◽  
Immunological Methods ◽  
Plasma Testosterone ◽  
Case Control Studies ◽  
Testosterone Levels ◽  
The Difference ◽  
Nested Case Control

AbstractThe aim of this review is to identify circulating steroids associated with prostate cancer (PCa) in bibliographic reports. First, we summarize chronological reports comparing circulating steroid levels in men with a high risk of PCa, such as African-Americans (AAs), with men having a lower risk. Higher testosterone plasma levels in young AA men have been reported. However, the difference between AAs and Caucasians decreases with age. When measured, dihydrotestosterone (DHT) was found to be higher in AAs; however, these results must be taken with caution, as immunological assay of this steroid is difficult. Second, we summarize chronological reports concerning circulating steroids assayed in blood samples drawn several years before a diagnosis of PCa was made, compared to controls. These nested case-control studies did not lead to straightforward conclusions regarding an increase in circulating testosterone. However, large collaborative studies showed a trend of a decrease in plasma sex hormone binding globulin, consequently an increase in bioavailable plasma testosterone in PCa. These nested case-control studies failed to associate plasma DHT levels with PCa risk. Third, we summarize numerous chronological publications relating plasma concentrations, measured at the time of PCa diagnosis. Numerous results showed a decrease in plasma testosterone levels in aggressive PCa (high Gleason score, advanced stage with positive surgical margins). Testosterone levels returned to normal several months after prostatectomy. All plasma hormone assay levels were always carried out using immunological methods. We recommend replacing this methodology by mass spectrometry coupled with gas chromatography or liquid chromatography in these epidemiologic studies.

scholarly journals Inter-annual stability and age-dependent changes in plasma testosterone levels in a longitudinally monitored free-living passerine bird

2020 ◽  
Author(s):  
Martin Tešický ◽  
Tereza Krajzingrová ◽  
Jiří Eliáš ◽  
Hana Velová ◽  
Jana Svobodová ◽  
...  
Keyword(s):  
Resource Allocation ◽  
Hormonal Regulation ◽  
Parus Major ◽  
Passerine Bird ◽  
Plasma Testosterone ◽  
Free Living ◽  
Testosterone Levels ◽  
Long Term Stability ◽  
Age Related ◽  
Age Dependent

AbstractWhile seasonal trends in the testosterone-driven hormonal regulation of resource allocation are known from cohort population samples, data on the inter-annual individual stability of blood plasma testosterone levels in wild birds are lacking, and our understanding of age-dependent changes is limited. We assessed plasma testosterone levels in 105 samples originating from 49 repeatedly captured free-living great tits (Parus major) to investigate their relative long-term stability and lifetime changes. Furthermore, we examined the inter-annual stability of selected condition-related traits (carotenoid- and melanin-based plumage ornamentation, ptilochronological feather growth rate, body mass, and haematological heterophil/lymphocyte ratio) and their relationships to testosterone levels. We show that testosterone levels in both sexes are inter-annually repeatable, both in their absolute values and individual ranks (indicating the maintenance of relative status in a population), yet with higher stability in females. Despite this stability, in males we found a quadratic dependence of testosterone levels on age, with a peak in midlife. In contrast, female testosterone levels showed no lifetime trend. The inter-annual stability of condition-related traits was mostly moderate and unrelated to plasma testosterone concentrations. However, males with elevated testosterone had significantly higher carotenoid-pigmented yellow plumage brightness, presumably serving as a sexually selected trait. Showing inter-annual stability in testosterone levels, this research opens the way to further understanding of the causes of variation in fitness-related traits. Based on a unique longitudinal dataset, this study demonstrates that male plasma testosterone undergoes age-related changes that may regulate resource allocation. Our results thus demonstrate that male birds undergo hormonal senescence similar to mammals.

Effects of oestradiol benzoate (OeB) and human chorionic gonadotrophin (hCG) on the testes and accessory sex glands of the rat

1981 ◽  
Vol 96 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Mridula Chowdhury ◽  
Robert Tcholakian ◽  
Emil Steinberger
Keyword(s):  
Treated Group ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Control Group ◽  
Intact Male ◽  
Intact Control ◽  
Testosterone Levels ◽  
Oestradiol Benzoate ◽  
Direct Inhibitory Effect

Abstract. It has been suggested that treatment of intact male rats with oestradiol benzoate (OeB) causes an interference with testosterone (T) production by the testes by a direct inhibitory effect on steroidogenesis. To test this hypothesis, different doses (5, 10 or 25 IU) of hCG were administered concomitantly with 50 μg of OeB to adult intact or hypophysectomized male rats. The testicular and plasma testosterone, and serum hCG levels were determined. The sex accessory weights were recorded. In the intact OeB-treated group of animals, hCG stimulated both the secondary sex organs and plasma testosterone levels above the intact control group. However, in hypophysectomized animals, although plasma testosterone levels increased above that of intact controls, their secondary sex organ weights did not. Moreover, inspite of high circulating hCG levels, the testicular testosterone content and concentration remained suppressed in OeB-treated animals. The reason for such dichotomy of hCG action on OeB-treated animals is not clear at present.

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