Hypophyso-adrenal regulation of moulting in the toad

Stefano, F. J. E.; Donoso, Alfredo O.

doi:10.1016/0016-6480(64)90055-3

Cited by 31 publications

(16 citation statements)

References 10 publications

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Section: Cort As a Molt Regulatormentioning

confidence: 99%

“…Adenohypophysectomized amphibians fail entirely to engage in their normally cyclic molt (Stefano and Donoso, 1964). 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).…”

Section: Cort As a Molt Regulatormentioning

confidence: 99%

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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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Section: Cort As a Molt Regulatormentioning

confidence: 99%

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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“…Unlike mammalian vertebrates, the slough is usually shed in its entirety, and then consumed, perhaps for the partial recycling of raw materials for future skin layers (Ling 1972;Weldon et al 1993;Duellman & Trueb 1994). While the mechanism is not fully understood, sloughing is hormonally controlled via the thyroid, pituitary, and adrenal glands (Jørgensen & Larsen 1960Barker Jørgensen et al 1965;Larsen 1976;, and follows an autonomous rhythm that is species-specific and may be influenced by age, size, and breeding timing Larsen 1976 dependent on ambient temperature, with moulting frequency increasing at higher temperatures (Stefano & Donoso 1964;. Given the regularity of the sloughing process and its importance for epidermal functioning, it may play an important role in immune defence in the face of invading cutaneous pathogens.…”

Section: Amphibian Skin Structure and Functionmentioning

confidence: 99%

“…To keep skin functioning and in optimal condition, the thin outer layer of keratinised skin cells, or stratum corneum, is regularly shed and replaced in a process called sloughing, the last step in epidermal turnover . Healthy frogs slough regularly, anywhere from every day to every other week, and sloughing rate varies across species and is positively correlated with temperature (Stefano & Donoso 1964;Castanho & de Luca 2001;. Recent work indicates that periodic skin sloughing results in up to a 100% short-term reduction of cutaneous flora and fauna .…”

Section: Introductionmentioning

confidence: 99%

“…This renewal process is termed sloughing or moulting, in which an amphibian sheds the outer skin layer, the stratum corneum, in its entirety on a regular basis (Larsen 1976). Sloughing is hormonally controlled (Barker Jørgensen et al 1965;, and occurs on a regular cycle anywhere from every 24 hours, to every two weeks, depending on the species (Stefano & Donoso 1964;Castanho & de Luca 2001;. Like most physiological processes in ectotherms, sloughing rate is affected by temperature .…”

Section: Introductionmentioning

confidence: 99%

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Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Ohmer¹

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Worldwide, there has been an unprecedented rise in emerging infectious diseases of wildlife, and this has contributed to a widespread biodiversity crisis. Amphibian populations, in particular, are threatened by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which in post-metamorphic animals only infects the skin, and causes the potentially lethal disease chytridiomycosis. Amphibians regularly slough their skin, and in doing so remove many skinassociated microbes. Thus, skin sloughing may play an important role in the pathogenesis of chytridiomycosis. To investigate this association, the influence of Bd infection on amphibian skin sloughing, and the role of sloughing in regulating infection, was examined. Furthermore, to better understand the variation in skin sloughing rates across species and ecological groups, and make inferences about the role of this process in susceptibility to this fungal disease, amphibian skin structure and function was investigated within a phylogenetic context. To determine the relationship between skin sloughing and disease progression (chapter 2), adult green tree frogs (Litoria caerulea) were exposed to an Australian Bd strain, and sloughing rates and infection load were monitored on a naturalistic cycling temperature regime (15 -23˚C).Sloughing rates were determined by filming frogs and infection intensity was monitored before and after sloughing with conventional swabbing and quantitative PCR. Sloughing rate was found to increase with Bd infection load in infected frogs, but sloughing itself did not affect Bd load on the ventral skin surface. Although a faster sloughing rate might be considered advantageous for Bdinfected animals, it does not appear to curb the progression of disease in susceptible species. In fact, sloughing may actually contribute to the loss of physiological homeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the skin.In some species less susceptible to chytridiomycosis, it has been demonstrated that Bd growth remains epibiotic, without penetrating the underlying epidermal layers. Therefore, sloughing may more effectively remove Bd zoospores in less susceptible species (chapter 3). To test this hypothesis, five Australian frog species, Lit. caerulea, Platyplectrum ornatum, Lechriodus fletcheri, Limnodynastes peronii, and Lim. tasmaniensis, were exposed to an Australian Bd strain, and their sloughing rates and infection loads monitored over time. Utilising an improved methodology to remove any artefacts from the swabbing itself, sloughing was found to reduce Bd load on the ventral skin surface, in all five species, despite wide ranging variation in susceptibility to Bd infection and subsequent disease. In less susceptible species, sloughing reduced Bd load up to 100%, leading to infection clearance. However, the drop in Bd load was only temporary in susceptible species, potentially due to the invasive growth of Bd in skin layers underlying the ii stratum corneum in these species. If less suscept...

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Relations of prolactin and thyroid hormone to molting, skin texture, and cutaneous secretion in the red‐spotted newt

1973

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The effects of prolactin on skin texture, on cutaneous secretion and on molting have been examined in the red-spotted newt under several hormonal conditions. In the adult newt skin is smooth and is covered with varying amounts of cutaneous secretion. Under laboratory conditions the skin ordinarily becomes rough and tuberculated within one or two weeks. Doses of 1.2-120 units of prolactin caused the skin of intact, laboratory-conditioned, red-spotted newts to become smooth and slimy. Similar changes were seen in newts bearing pituitary autografts which are presumed to secrete excessive amounts of prolactin or prolactin-like hormone. No change in skin texture or secretion was detected in hypophysectomized newts treated with prolactin. It has been reported recently that 120 units of prolactin induces molting in the hypophysectomized European crested newt (Vellano et al., '70). Although 3 of 15 hypophysectomized red-spotted newts molted in response to that dose of prolactin, TSH in amounts equivalent to that which may have contaminated the prolactin produced similar results. Thyroidectomized newts showed no cutaneous response to 120 units of prolactin. Thyroidectomized newts kept i n water to which 10 pgm/liter of 1-thyroxine had been added molted only rarely, but when thyroidectomized animals were put into 10 pgm/liter of 1-thyroxine and injected with 12 units of prolactin they began to molt normally and their skins became smooth and slimy. It is concluded that in the red-spotted newt prolactin alone does not induce molting but may facilitate molting, probably through the stimulation of cutaneous secretion, when introduced with thyroid hormone. It is further concluded that although prolactin induces changes in skin texture and in cutaneous secretion, those responses are to some extent mediated by the thyroid hormone.It has long been accepted that the thyroid is the endocrine gland that exercises primary control over molting in the urodeles (Adams and Richards, '29; Adams, Kuder and Richards, '32; Osborn, '36; Jmrgensen and Larsen, '60; Clark and Kaltenbach, '61). Recently, however, it has been reported that prolactin induces molting in hypophysectomized (Vellano et al., '70) and in thyroidectomized and castrated (Vellano, Mazzi and Sacerdote, '70) specimens of the European crested newt (Triturus cristatus carnifex). Although rejected by some workers (Adolph and Collins, '25; Adams and Gierson, '32; Clark and Kaltenbach, '61), the suggestion has been put forth (Schultz, 1889; Dennert, '24; Chadwick, '48), that in J. EXP. ZOOL, 184 36S382 molting, cutaneous secretion accumulates beneath the slough, forcing it from the body. Various findings have given indication that prolactin affects skin texture and cutaneous secretion both in the redspotted newt (Adams, '32; Reinke and Chadwick, '40; Grant and Grant, '58) and in the crested newt (Vellano, Mazzi and Sacerdote, '70).The present study explores the question of whether or not prolactin is capable of stimulating molting in the red-spotted newt (Notophthalmus v...

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Hypophyso-adrenal regulation of moulting in the toad

Cited by 31 publications

References 10 publications

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

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

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Relations of prolactin and thyroid hormone to molting, skin texture, and cutaneous secretion in the red‐spotted newt

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