Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians

Maraghi-Ater, Hakima El; Mesnard, J.; Hourdry, J.

doi:10.1016/0016-6480(86)90248-0

Cited by 11 publications

(1 citation statement)

References 33 publications

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“…TH treatment of small intestine cultured in vitro also caused larval cell degeneration (72), but adult epithelium failed to proliferate sufficiently (73), adult-type microvilli did not form (74), and adult-pattern lectin binding failed to occur (72). In addition, the adult epithelium achieved by natural metamorphosis and the epithelium achieved by TH treatment responded to GCs, specifically hydrocortisone, differently (75, 76). In particular, hydrocortisone increased intestinal digestive enzymes after natural metamorphosis but decreased them after TH-induction.…”

Section: Analysis Of the Sufficiency Of Th/tr Signaling In Frog Metammentioning

confidence: 99%

Insufficiency of Thyroid Hormone in Frog Metamorphosis and the Role of Glucocorticoids

Sachs

Buchholz

2019

Front. Endocrinol.

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Thyroid hormone (TH) is the most important hormone in frog metamorphosis, a developmental process which will not occur in the absence of TH but can be induced precociously by exogenous TH. However, such treatments including in-vitro TH treatments often do not replicate the events of natural metamorphosis in many organs, including lung, brain, blood, intestine, pancreas, tail, and skin. A potential explanation for the discrepancy between natural and TH-induced metamorphosis is the involvement of glucocorticoids (GCs). GCs are not able to advance development by themselves but can modulate the rate of developmental progress induced by TH via increased tissue sensitivity to TH. Global gene expression analyses and endocrine experiments suggest that GCs may also have direct actions required for completion of metamorphosis independent of their effects on TH signaling. Here, we provide a new review and analysis of the requirement and necessity of TH signaling in light of recent insights from gene knockout frogs. We also examine the independent and interactive roles GCs play in regulating morphological and molecular metamorphic events dependent upon TH.

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Section: Analysis Of the Sufficiency Of Th/tr Signaling In Frog Metammentioning

confidence: 99%

Insufficiency of Thyroid Hormone in Frog Metamorphosis and the Role of Glucocorticoids

Sachs

Buchholz

2019

Front. Endocrinol.

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In vitro study of the intestinal brush border enzyme activities in developing anuran amphibian: Effects of thyroxine, cortisol, and insulin

Pouyet¹,

Hourdry²

1988

J. Exp. Zool.

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The effects of several hormones on intestinal brush border membrane enzymatic activities have been investigated in intestinal explants taken from the amphibian midwife toad at different developmental stages. Explants were treated for at least 2 days with thyroxine (0.1 microgram/ml of culture medium) or for 2 days with cortisol (25 micrograms/ml) or insulin (6 mU/ml). The hydrolases examined were maltase, trehalase, glucoamylase, and alkaline phosphatase. In the explants from tadpoles in prometamorphosis, thyroxine had no effect on hydrolase activities; cortisol increased the activity of only glucoamylase, and insulin increased activity of maltase, glucoamylase, and alkaline phosphatase. When the explants were taken from tadpoles at the beginning of climax, cortisol and insulin generally stimulated the enzyme activities studied. When taken from tadpoles at the end of climax, at the moment when the embryonic cells under the degenerating epithelium divide, cortisol and insulin had little effect on these activities. When the animals terminate their metamorphosis, the intestinal epithelium of the explants is totally newly formed (secondary epithelium). At this time, cortisol stimulated the activities of maltase, glucoamylase, and alkaline phosphatase, while insulin decreased the activities of maltase and glucoamylase.

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Histological examination of the effects of corticosterone in larvae of the western toad, Bufo boreas (Anura: Bufonidae), and the oriental fire‐bellied toad, Bombina orientalis (Anura: Discoglossidae)

Hayes

1995

Journal of Morphology

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The effects of corticosterone (CORT)-treatment on various tissues were examined in two species of anuran larvae, the discoglossid Bombina orientalis, and the bufonid Bufo boreas. Corticosterone was administered directly into aquarium water for 15 days. After treatment, histological analyses were conducted on skin, gut, spleen, thymus, and neural and muscle tissue. Corticosterone treatment prevented sloughing of the skin, which resulted in a build-up of stratum corneum, and inhibited the development of gland nests and the subsequent formation of dermal granular and mucous glands in both species. Corticosterone treatment also decreased epithelial folding in the gut and caused vesiculation of the gut epithelial cells. The thymus of CORT-treated animals was significantly reduced in size (P < .05) and cell density (P < .05), and the spleen of CORT-treated animals was completely involuted. The brain and pituitary of CORT-treated animals had a decreased cell density (P < .05) and many pyknotic cells. An examination of muscle revealed that muscle fibers of CORT-treated animals had a decreased cross-sectional area (P < .05). The dose of CORT used (1.1 microM) was within the range used in other studies in the literature and resulted in tissue levels within the range experienced by larvae at metamorphic climax. Thus, this study is appropriate to address the histological effects of CORT in experimental manipulations and the role of increasing CORT at metamorphic climax. The data suggest that increasing endogenous CORT at metamorphosis may be involved in degeneration of larval tissue, prior to regeneration, which is stimulated by thyroid hormones.

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Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians

Cited by 11 publications

References 33 publications

Insufficiency of Thyroid Hormone in Frog Metamorphosis and the Role of Glucocorticoids

Insufficiency of Thyroid Hormone in Frog Metamorphosis and the Role of Glucocorticoids

In vitro study of the intestinal brush border enzyme activities in developing anuran amphibian: Effects of thyroxine, cortisol, and insulin

Histological examination of the effects of corticosterone in larvae of the western toad, Bufo boreas (Anura: Bufonidae), and the oriental fire‐bellied toad, Bombina orientalis (Anura: Discoglossidae)

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