The relationship of thyroxine and cortisol to the moult of the harbor seal Phoca vitulina

Riviere, J. E.; Engelhardt, F. R.; Solomon, Jolane

doi:10.1016/0016-6480(77)90027-2

Cited by 45 publications

(26 citation statements)

References 14 publications

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“…While cortisol concentrations have been reported for harbor seals in relation to molting (Riviere et al, 1977;Ashwell-Erickson et al, 1986), breeding (Gardiner and Hall, 1997) and seasonal and diurnal patterns (Gardiner and Hall, 1997;Oki and Atkinson, 2004), there is comparatively limited information available for aldosterone concentrations in harbor seals (St. Aubin and Geraci, 1986;Gulland et al, 1999). Of interest in the present study is the significant increase in aldosterone concentration, which was correlated with cortisol concentrations following ACTH administration, demonstrating that secretion of aldosterone is also under the HPA axis control as has been previously demonstrated in phocids (St. Aubin and Geraci, 1986;Gulland et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

“…In addition to its role in the stress response, cortisol, the prominent GC in pinnipeds (DeRoos and Bern, 1961;Sangalang and Freeman, 1976), regulates gluconeogenesis promoting the mobilization of fatty acids from peripheral adipose tissues . In phocids, cortisol has been suggested to play a role during molting (Riviere et al, 1977;Ashwell-Erickson et al, 1986;Boily, 1996), lactation (Engelhard et al, 2002), fasting (Ortiz et al, 2001a(Ortiz et al, , 2001b(Ortiz et al, , 2003aRosen and Kumagai, 2008) and potentially during diving (Zapol et al, 1979). While aldosterone secretion is influenced by the HPA axis during a stress response, it has been thought to be predominately under regulation by the reninangiotensin system in pinnipeds (Malvin et al, 1975;Ortiz et al, , 2003bOrtiz et al, , 2006Houser et al, 2001) with secretion stimulated by angiotensin II in order to maintain water and electrolyte balance.…”

Section: Introductionmentioning

confidence: 99%

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Endocrine and immunological responses to adrenocorticotrophic hormone (ACTH) administration in juvenile harbor seals ( Phoca vitulina ) during winter and summer

Keogh

Atkinson

2015

Comparative Biochemistry and Physiology Part A: Molecular &

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Endocrine and immunological responses to adrenocorticotrophic hormone (ACTH) administration in juvenile harbor seals ( Phoca vitulina ) during winter and summer

Keogh

Atkinson

2015

Comparative Biochemistry and Physiology Part A: Molecular &

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“…Cyclical molt is restored in these animals when they are given cortisol implants (Stefano and Donoso, 1964), but if exogenous cortisol is given to intact animals the molt period is greatly extended (Barker Jørgensen, 1988). In mammals, CORT can be either relatively high or low during pelage molt, but levels may relate more meaningfully to specific stages of hair shedding vs new growth (Boily, 1996;Riviere et al, 1977;Weiss et al, 1980). It is plausible that CORT has direct influences on the mechanisms involved with integument replacement in birds.…”

Section: Cort As a Molt Regulatormentioning

confidence: 99%

Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Cornelius

Perfito

Zann

et al. 2011

Journal of Experimental Biology

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SUMMARYTrade-offs between self-maintenance processes can affect life-history evolution. Integument replacement and the stress response both promote self-maintenance and affect survival in vertebrates. Relationships between the two processes have been studied most extensively in birds, where hormonal stress suppression is down regulated during molt in seasonal species, suggesting a resource-based trade-off between the two processes. The only species found to differ are the rock dove and Eurasian tree sparrow, at least one of which performs a very slow molt that may reduce resource demands during feather growth, permitting investment in the stress response. To test for the presence of a molt-stress response trade-off, we measured hormonal stress responsiveness during and outside molt in two additional species with extended molts, red crossbills (Loxia curvirostra) and zebra finches (Taeniopygia guttata). We found that both species maintain hormonal stress responsiveness during molt. Further, a comparative analysis of all available species revealed a strong relationship between molt duration and degree of hormonal suppression. Though our results support trade-off hypotheses, these data can also be explained by alternative hypotheses that have not been formally addressed in the literature. We found a strong relationship between stress suppression and seasonality of breeding and evidence suggesting that the degree of suppression may be either locally adaptable or plastic and responsive to local environmental conditions. We hypothesize that environmental unpredictability favors extended molt duration, which in turn allows for maintenance of the hormonal stress response, and discuss implications of a possible trade-off for the evolution of molt schedules. Supplementary material available online at

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“…Thyroxine has been shown to stimulate hair growth, while corticosteroids and epinephrine inhibit it in mammals that show continuous hair replacement (Chang 1926;Mohn 1958;Bullough 1962;Ebling and Johnson 1964;Bullough and Rytomaa 1965). Reports of the effects of thyroxine and corticosteriods in mammals undergoing a complete, seasonal molt and replacement (Rust 1965; Rust et al 1965) are conflicting, possibly (as pointed out by Riviere et al, 1977) because inappropriate criteria were used to assess hormonal activity, and the ability of the species to respond to hormonal stimulation at specific times during the pelage cycle was unknown. Nutritional status may affect pelage growth by 'thyroid feedback, influencing adrenal output, or both (Ryder 1958;Ling 1970).…”

Section: Introductionmentioning

confidence: 99%

Metabolic and hormonal correlates of molting and regeneration of pelage in Alaskan harbor and spotted seals (Phoca vitulina and Phoca largha)

Ashwell-Erickson¹,

Fay²,

Elsner³

et al. 1986

Can. J. Zool.

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1986. Metabolic and hormonal correlates of molting and regeneration of pelage in Alaskan harbor and spotted seals (Phoca vitulina and Phoca largha). Can. J . Zool. 64: 1086-1094. Cellular, hormonal, and metabolic changes during annual molts and regeneration of the pelage were studied in two harbor and five spotted seals of different ages. Seals were maintained in an appropriate photoperiod and monitored biweekly to monthly by measuring their serum cortisol, thyroxine, and triiodothyronine and their standardized resting metabolic rate. Concurrently, external signs of their molt (shedding of hair) were recorded, and samples of skin were collected from the midback for histological determination of the duration of the regenerative phase of the pelage cycle. Timing of the molts coincided with those of free-ranging seals in the natural environment. The overall duration of the period of shedding and regeneration, from first descent of the hair bulbs on the face and flippers to full emergence of new hair on the back, was estimated as 120-170 days. During the period of descent of the hair bulbs and initial growth of new hair on the back, the resting metabolic rate declined an average of 18.6% below premolt values, generally reaching its minimum when shedding of the old hair and rapid growth of new hair began. Serum cortisol generally reached a maximum just before or during the main shedding of hair from the torso, then decreased abruptly to its premolt level or lower during the main period of rapid growth of new hair. Although corticosteroids appear to inhibit protein anabolism, they favor fat catabolism and may in this way help to maintain the slow growth of new hair before and during the first part of the molt. Serum concentrations of thyroid hormones declined to minima early in the molt, then increased to maxima toward the end, when growth of new hair was most rapid. ASHWELL-ERICKSON, S., F. H. FAY, R. ELSNER et D. WARTZOK. 1986. Metabolic and hormonal correlates of molting and regeneration of pelage in Alaskan harbor and spotted seals (Phoca vitdina and Phoca largha). Can. J . Zool. 64: 1086-1094. Les changements cellulaires, hormonaux et mktaboliques au cours de la rnue annuelle et du renouvellement du pelage ont fait l'objet d'une Ctude chez des phoques, deux P. vitulina et cinq P. larghu de diffkrents iiges. Les phoques Ctaient gardCs dans un environnement B photophiode appropriCe et des manipulations, a raison de deux par semaine a une par mois, permettaient de mesurer leurs concentrations de cortisol, de thyroxine et de triiodothyronine sCriques et d'Cvaluer leur taux de mCtabolisme au reps.En mCme temps, les manifestations externes de la rnue (perte de poils), Ctaient notkes et des Cchantillons de peau sur le milieu du dos Ctaient prClevCs pour permettre 1'Cvaluation histologique de la durCe de la phase de renouvellement du pelage. La @ride de la rnue coincidait avec celle de phoques libres en nature. La dude totale de la pCriode de perte de poils et de la p6riode de renouvellement du pelagem, c'est-a-dire du pr...

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The relationship of thyroxine and cortisol to the moult of the harbor seal Phoca vitulina

Cited by 45 publications

References 14 publications

Endocrine and immunological responses to adrenocorticotrophic hormone (ACTH) administration in juvenile harbor seals ( Phoca vitulina ) during winter and summer

Endocrine and immunological responses to adrenocorticotrophic hormone (ACTH) administration in juvenile harbor seals ( Phoca vitulina ) during winter and summer

Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Metabolic and hormonal correlates of molting and regeneration of pelage in Alaskan harbor and spotted seals (Phoca vitulina and Phoca largha)

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