Excretion and metabolic fate of radiolabeled estradiol and testosterone in the cockatiel (Nymphicus hollandicus)

Tell, Lisa A.

doi:10.1002/(sici)1098-2361(1997)16:6<505::aid-zoo4>3.0.co;2-e

Cited by 16 publications

(16 citation statements)

References 24 publications

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“…In contrast to plasma T, fecal T levels show less variation and rarely reflect acute responses, but provide a cumulative measure over a prolonged period of time (Ninnes et al 2010). The rate at which T is excreted in feces depends on the overall metabolism and defecation frequency of the organism (Palme 2005), but a reasonable estimate is 24-48 h (Tell 1997). Therefore, we do not find a daily pattern in T levels although there is evidence that it exists in plasma T (Kempenaers et al 2008).…”

Section: Discussioncontrasting

confidence: 54%

Seasonal and urban effects on the endocrinology of a wild passerine

Russ

Reitemeier

Weißmann

et al. 2015

Ecology and Evolution

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In order to maximize their fitness, organisms in seasonal environments rely on external cues to optimally time their life‐history stages. One of the most important zeitgeber to time reproduction is the photoperiod, but further environmental cues are assessed to fine‐tune reproduction due to year‐to‐year variation in environmental conditions. However, in urbanized environments, the pervasive artificial light at night has altered the natural signal of light and darkness. Accordingly, artificial light at night was repeatedly shown to affect avian reproductive physiology and to advance seasonal reproduction in birds. However, these experiments were mainly conducted in the absence of further environmental cues to facilitate the investigation of the mechanisms which are still poorly understood. Here, we investigate whether the endocrine system of free‐ranging European blackbirds (Turdus merula) correlates with the amount of artificial light at night along a rural to urban gradient while the birds still encounter complementary environmental cues including seasonal variation in day length and temperature. Testosterone and estrone were assessed as metabolites in fecal samples and corticosterone in blood from mist‐netted blackbirds. We demonstrate that seasonal fluctuations in abiotic factors, individual conditions, but also light at night affect the reproductive and stress physiology of wild European blackbirds. Elevated artificial night light intensities were significantly positively correlated with corticosterone and negatively with female estrone levels. No effects of artificial light were found for testosterone levels. Our results suggest that female blackbirds in particular perceive even low levels of artificial light at night as a weak but chronic stressor that interacts with the hypothalamic‐pituitary‐gonadal axis and leads to a reduced secretion of reproductive hormones. These findings point out that the impacts of light pollution are diverse and we only slowly disentangle its multiple effects on physiology, ecology, and biodiversity.

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Section: Discussioncontrasting

confidence: 54%

Seasonal and urban effects on the endocrinology of a wild passerine

Russ

Reitemeier

Weißmann

et al. 2015

Ecology and Evolution

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“…They can be used to measure the time lag between secretion and excretion of a hormone, 10,11,16,17 they give information about the proportional allocation of hormone metabolites to urine and feces, [16][17][18][19][20] and they allow the determination of whether the antibody really cross-reacts with metabolites of the hormone in question. 10,11,[16][17][18][19][20][21][22] The disadvantage of radioinfusion studies is that they typically require special permits and equipment regarding animal care facilities and the generation of radioactive waste. This is relatively easy to accomplish when working with small songbirds, but I have due respect for investigators who have done this with large mammals such as horses, cattle, 17 and elephants.…”

Section: Radioinfusion Studiesmentioning

confidence: 99%

“…2,12,and 36). Some researchers prefer to take only the fecal part for analysis, 29,[37][38][39] whereas others take the whole sample, 10,11,21 assuming that a true separation is not possible, because the urine and fecal part of the excreta are already mixed inside the cloaca and when voided on the ground (see also Refs. 2, 12, and 13).…”

Section: Sampling and Processing Of Feces Or Bird Droppingsmentioning

confidence: 99%

Noninvasive Monitoring of Hormones in Bird Droppings: Physiological Validation, Sampling, Extraction, Sex Differences, and the Influence of Diet on Hormone Metabolite Levels

Goymann

2005

Annals of the New York Academy of Sciences

209

217

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During the past several years, the noninvasive measurement of steroid metabolites from mammalian feces and bird droppings has become more and more popular. With an increasing acceptance of the method, investigators may become less aware of the need to validate their assays. It is shown why such validations are essential for each new species investigated and various ways to physiologically validate such noninvasive methods are described. Using the European stonechat (Saxicola torquata rubicola) as a model, it is explained why a validated method to measure androgen metabolites in males does not necessarily work in females. In addition the difficulties that may be neglected owing to the superficial ease of sampling and processing of excreta are investigated. Various issues that may arise during sampling, storage, and extraction of excreta are addressed. Finally, results suggesting that experimental manipulations of the diet may affect hormone metabolite levels in European stonechats are presented. So far, only a few studies have investigated the impact of diet on hormone metabolite levels, and these are the first data to report such an impact in birds. More studies are urgently needed to learn more about differences between the sexes, individuals, and populations and the impact of diet and energy metabolism on hormone metabolites.

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“…Fecal hormone measures have been extensively validated in mammals. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] However, relatively few studies have validated such measures for avian species 10,[24][25][26][27][28][29] (for a detailed list see Touma and Palme 43 ). Such validations are especially critical in birds, in which feces, urine, and urates are all excreted together.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive Measures of Reproductive Function and Disturbance in the Barred Owl, Great Horned Owl, and Northern Spotted Owl

Wasser

Hunt

2005

Annals of the New York Academy of Sciences

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There is an urgent need for noninvasive methods to study reproduction and environmental stress in at-risk species such as the northern spotted owl (Strix occidentalis caurina). Two related owl species (barred owl and great horned owl) were used as surrogates to validate hormone assays for fecal metabolites of progesterone, 17beta-estradiol, testosterone, and corticosterone. Infusions of radiolabeled hormones showed that the owls excreted most hormone within 6 h. Feces and urine contained roughly equal amounts of hormone, and most fecal hormone metabolites were quite polar. The testosterone and corticosterone assays in this study bound to the major excreted metabolites of these hormones, but two progesterone assays did not appreciably bind to the major progesterone metabolites. All assays showed excellent parallelism with hydrolyzed and unhydrolyzed samples and with previously dried or undried fecal samples. Thus, samples do not require hydrolysis or prior drying. Samples from a female barred owl had significantly higher fecal estrogen, lower fecal testosterone, and higher fecal estrogen/testosterone ratio than samples from two male barred owls. The fecal estrogen/testosterone ratio was the most accurate predictor of owl gender, particularly if two or more samples are available from the same individual. Fecal corticosterone metabolites also demonstrated considerable utility for wild northern spotted owls. Fecal glucocorticoid levels varied by gender and breeding stage, being highest in male northern spotted owls early in the breeding season and highest in females when nestlings were fledging. Collectively, these studies show that noninvasive fecal hormone measurements show great promise for noninvasive assessment of reproduction and stress in wild owls.

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Excretion and metabolic fate of radiolabeled estradiol and testosterone in the cockatiel (Nymphicus hollandicus)

Cited by 16 publications

References 24 publications

Seasonal and urban effects on the endocrinology of a wild passerine

Seasonal and urban effects on the endocrinology of a wild passerine

Noninvasive Monitoring of Hormones in Bird Droppings: Physiological Validation, Sampling, Extraction, Sex Differences, and the Influence of Diet on Hormone Metabolite Levels

Noninvasive Measures of Reproductive Function and Disturbance in the Barred Owl, Great Horned Owl, and Northern Spotted Owl

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