Ecophysiological Studies of Hormone-Behavior Relations in Birds

Wingfield, John C.; Silverin, Bengt

doi:10.1016/b978-012532104-4/50033-0

Cited by 54 publications

(39 citation statements)

References 282 publications

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“…It is well established that glucocorticosteroids promote energy mobilization (Munck et al, 1984;Wingfield and Silverin, 2002) and that baseline levels vary seasonally in many vertebrate species (Romero, 2002). Higher plasma levels of corticosterone during breeding may reflect increased energy costs associated with reproductive effort, such as gonadal development, territorial defense, and high testosterone levels (Bentley et al, 1998;Ketterson and Nolan, Jr, 1999;Martin et al, 2003;Greenman et al, 2005).…”

Section: Corticosteronementioning

confidence: 99%

“…In seasonally breeding birds, androgen levels are reduced in captive males exposed to long daylengths (breeding conditions), presumably because appropriate social and environmental stimuli necessary to stimulate the reproductive axis and secretion of testosterone above a breeding baseline are lacking or insufficient (Wingfield and Silverin, 2002). Thus, in free-living birds, high circulating androgen levels during breeding could potentially mediate the behavioral insensitivity to LPS by regulating the suppression of sickness behavior.…”

Section: Testosteronementioning

confidence: 99%

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Seasonal modulation of sickness behavior in free-living northwestern song sparrows (Melospiza melodia morphna)

Owen-Ashley

Wingfield

2006

Journal of Experimental Biology

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111

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SUMMARY A variety of vertebrate species modulate immune function on a seasonal basis to cope with seasonal energy deficits and competing life-history demands, such as reproduction. Most studies to date have focused upon seasonal variation of cellular and humoral immunity, while neglecting behavioral responses to infection. These behavioral strategies are collectively termed sickness behaviors and are hypothesized to divert energy away from normal activities to combat and overcome infection. Sickness behavior can be triggered experimentally by injecting bacterial lipopolysaccharide (LPS). In this study, we provide the first evidence for seasonal modulation of sickness behavior in a free-living animal. Male song sparrows of western Washington state (Melospiza melodia morphna) are sedentary and territorial year round, except for a brief time during molt. Treatment with LPS decreased territorial aggressive behavior of males in the winter (nonbreeding), but not in the spring (breeding). Subjects were recaptured approx. 25 h after treatment. Recaptured LPS males in the winter lost more body mass than saline-injected controls while LPS males in the spring did not. These data indicate that birds in breeding condition were relatively insensitive to the effects of LPS. On a proximate level, suppression of sickness behavior during breeding is likely mediated by seasonal differences in energy allocation, as wintering sparrows were significantly heavier and had larger subcutaneous fat reserves and lower baseline corticosterone levels than breeding birds. Ultimately, suppression of sickness behavior may represent an allocation strategy to balance current reproductive opportunities with the life-history costs of self-defense.

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Section: Corticosteronementioning

confidence: 99%

Section: Testosteronementioning

confidence: 99%

Seasonal modulation of sickness behavior in free-living northwestern song sparrows (Melospiza melodia morphna)

Owen-Ashley

Wingfield

2006

Journal of Experimental Biology

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111

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“…Steroids exert profound organizational effects on the developing brain and the increase of secretion of sex steroid hormones at puberty and their maintenance throughout the reproductive life are responsible for the activation and maintenance of secondary sex characters and behaviors such as courtship, reproductive behavior, aggressive behaviors, etc [34]. Seasonal fluctuations and/or variations across the estrus cycle of circulating levels of estrogens positively correlate with variation in these reproductive responses [13,198,282]. A variety of effects of estrogens and other steroids on responses unrelated to reproduction have also been identified.…”

Section: Introductionmentioning

confidence: 99%

Functional significance of the rapid regulation of brain estrogen action: Where do the estrogens come from?

2006

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Estrogens exert a wide variety of actions on reproductive and non-reproductive functions. These effects are mediated by slow and long lasting genomic as well as rapid and transient non-genomic mechanisms. Besides the host of studies demonstrating the role of genomic actions at the physiological and behavioral level, mounting evidence highlights the functional significance of non-genomic effects. However, the source of the rapid changes in estrogen availability that are necessary to sustain their fast actions is rarely questioned. For example, the rise of plasma estrogens at pro-estrus that represents one of the fastest documented changes in plasma estrogen concentration appears too slow to explain these actions. Alternatively, estrogen can be synthesized in the brain by the enzyme aromatase providing a source of locally high concentrations of the steroid. Furthermore, recent studies demonstrate that brain aromatase can be rapidly modulated by afferent inputs, including glutamatergic afferents. A role for rapid changes in estrogen production in the central nervous system is supported by experiments showing that acute aromatase inhibition affects nociception as well as male sexual behavior and that preoptic aromatase activity is rapidly (within min) modulated following mating. Such mechanisms thus fulfill the gap existing between the fast actions of estrogen and their mode of production and open new avenues for the understanding of estrogenic effects on the brain.

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“…Testosterone is the dominant androgen secreted from the avian gonads (Wingfield and Silverin, 2002), but there is mounting evidence that DHEA is a significant avian hormone with potent neural actions (Goodson et al, 2005). The most likely mechanism for DHEA action on the brain is via conversion into more potent sex steroids by the action of the enzyme 3β-hydroxysteroid dehydrogenase/isomerase (3βHSD).…”

Section: Introductionmentioning

confidence: 99%

Activities of 3β-HSD and aromatase in slices of developing and adult zebra finch brain

Tam¹,

Schlinger²

2007

General and Comparative Endocrinology

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Sex steroids influence the development and function of the songbird brain. Developmentally, the neural circuitry underlying song undergoes masculine differentiation under the influence of estradiol. In adults, estradiol stimulates song behavior and the seasonal growth of song control circuits. There is good reason to believe that these neuroactive estrogens are synthesized in the brain. At all ages, estrogens could act at the lateral ventricle, during migration, or where song nuclei exist or will form. We investigated the activity of two critical steroidogenic enzymes, 3β-hydroxysteroid dehydrogenase/isomerase (3βHSD) and aromatase, using a slice culture system. Sagittal brain slices were collected from juvenile (posthatch day 20) and adult zebra finches containing either the lateral ventricle, where neurons are born, or the telencephalic song nuclei HVC and RA. The slices were incubated with 3 H dehydroepiandrosterone or 3 H-androstenedione. Activity was determined by isolating certain products of 3βHSD (5α-androstanedione, 5β-androstanedione, estrone, and estradiol) and aromatase (estrone and estradiol). Activities of both 3βHSD and aromatase were detected in all slices and were confirmed using specific enzyme inhibitors. We found no significant difference in activity between adult males and females in either region for either enzyme. Juvenile female slices containing the lateral ventricle, however, showed greater levels of 3βHSD activity than did similar slices from age-matched males. Determination of the activity of these critical steroidogenic enzymes in slice culture has implications for the role of neurosteroids in brain development.

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Ecophysiological Studies of Hormone-Behavior Relations in Birds

Cited by 54 publications

References 282 publications

Seasonal modulation of sickness behavior in free-living northwestern song sparrows (Melospiza melodia morphna)

Seasonal modulation of sickness behavior in free-living northwestern song sparrows (Melospiza melodia morphna)

Functional significance of the rapid regulation of brain estrogen action: Where do the estrogens come from?

Activities of 3β-HSD and aromatase in slices of developing and adult zebra finch brain

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