Seasonal fluctuations in plasma testosterone levels and diurnal song activity in free-living male great tits

Growth and development of the pedicles and first antlers were monitored in seven reindeer (Rangifer tarandus tarandus) calves (three males, four females) from birth to 1 year of age. Calves were weighed, blood was sampled, and antler observations and (or) measurements were taken on the day of birth and days 2, 4, and 7 and then at weekly intervals for the remainder of the year. Prior to measurable growth, the frontal lateral crest was carefully palpated for evidence of pedicle initiation, starting on the day of birth. Calves were born between April 8 and 26, 1994. Pedicle initiation occurred in all reindeer by day 7. Velvet skin first appeared when calves were 4-6 weeks old, when estimated pedicle height was 3.5 ± 0.9 cm (mean ± SD). Antler growth in both sexes followed a sigmoidal pattern, producing a mean antler length of 33.5 ± 4.2 and 46.7 ± 13.8 cm in females and males, respectively. Antler growth was complete by week 18 in females and week 21 in males. Velvet cleaning was associated with a significant increase in plasma testosterone levels in males and estradiol-17beta (but not testosterone) levels in females. Insulin-like growth factor 1 levels were significantly higher in males than in females and were positively correlated with the period of most rapid antler growth in both sexes. Casting occurred between March 14 and April 17, when steroid levels were at a minimum, and was immediately followed by growth of the second antler.

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

Frontiers in Zoology ◽

10.1186/s12983-021-00389-x ◽

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.

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Seasonal fluctuations in plasma testosterone levels and testes size in male goat (Capra hircus)-ibex (Capra ibex nubiana) crosses

Comparative Biochemistry and Physiology Part A Physiology ◽

10.1016/0300-9629(81)90163-8 ◽

1981 ◽

Vol 69 (4) ◽

pp. 713-716 ◽

Cited By ~ 5

Author(s):

A.A Degen ◽

U.A Sod-Moriah ◽

Y Levy ◽

D Rattner

Keyword(s):

Capra Hircus ◽

Plasma Testosterone ◽

Seasonal Fluctuations ◽

Capra Ibex ◽

Testosterone Levels ◽

Testes Size

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

10.1101/2020.07.23.217836 ◽

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.

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

Canadian Journal of Zoology ◽

10.1139/z04-150 ◽

2004 ◽

Vol 82 (11) ◽

pp. 1795-1803 ◽

Cited By ~ 16

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.

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

Acta Endocrinologica ◽

10.1530/acta.0.0680576 ◽

1971 ◽

Vol 68 (3) ◽

pp. 576-584 ◽

Cited By ~ 5

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.

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

Acta Endocrinologica ◽

10.1530/acta.0.0960273 ◽

1981 ◽

Vol 96 (2) ◽

pp. 273-280 ◽

Cited By ~ 1

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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