Thyroid hormone-induced demineralisation of the vertebral skeleton of the eel, Anguilla anguilla

Sbaihi, Miskal; Kacem, Adnane; Aroua, Salima; Baloche, S.; Rousseau, Karine; Lopez, Évelyne; Meunier, François; Dufour, Sylvie

doi:10.1016/j.ygcen.2006.12.009

Cited by 27 publications

(38 citation statements)

References 64 publications

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“…Blood was collected on heparin and plasma, obtained after centrifugation, was stored at K20 8C until steroid, calcium, phosphate, and vitellogenin (Vg) assays. For each animal, a portion of vertebral skeleton was sampled 2 cm behind the anal region according to Sbaihi et al (2007).…”

Section: Hormonal Treatmentmentioning

confidence: 99%

“…01 mg (Mettler AC 100), incinerated for 7 hours at 850 8C and the ashes weighed (mineral weight) to a precision of 0 . 01 mg, as described earlier (Sbaihi et al 2007). The mineral ratio (MR) which is the quantity of mineral per unit mass of dried material was calculated as followed: MR (%)Z(mineral weight/dry weight)!100.…”

Section: Measurement Of Mineral Ratio By Incinerationmentioning

confidence: 99%

“…Briefly, slices (100G1 mm) of embedded (Stratyl: chronolite 2195) vertebrae were microradiographied with a CGR Sigma 2060 X-ray generator. The settings of the X-ray unit were 20 kV, 7 mA, 60 min exposure time and a distance of 40 cm between the beam source and the X-ray film (Sbaihi et al 2007). The microradiographied vertebrae were compared with the optical density of 99 .…”

Section: Measurement Of Mineralization Degree By Quantitative Microramentioning

confidence: 99%

“…The microradiographied vertebrae were compared with the optical density of 99 . 9% pure foil aluminium standard (Strems Chemical Ltd, Strasbourg, France) of increasing thickness (Boivin & Baud 1984, Meunier & Boivin 1997, Kacem & Meunier 2003, Sbaihi et al 2007). Data could be converted from gray-level values (optical densities) to degree of mineralization, i.e.…”

Section: Measurement Of Mineralization Degree By Quantitative Microramentioning

confidence: 99%

“…We undertook histological and histophysical (qualitative and quantitative microradiographs) studies on vertebral bone of control and cortisol-treated silver eels, according to the methods we recently developed in the eel (Sbaihi et al 2007). We also investigated the specificity of cortisol action by comparing its effects with those of sex steroids.…”

Section: Introductionmentioning

confidence: 99%

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Cortisol mobilizes mineral stores from vertebral skeleton in the European eel: an ancestral origin for glucocorticoid-induced osteoporosis?

Sbaihi

Rousseau

Baloche

et al. 2009

Journal of Endocrinology

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Endogenous excess cortisol and glucocorticoid (GC) therapy are a major cause of secondary osteoporosis in humans. Intense bone resorption can also be observed in other vertebrates such as migratory teleost fish at the time of reproductive migration and during fasting when large amounts of calcium and phosphate are required. Using a primitive teleost, the European eel, as a model, we investigated whether cortisol could play an ancestral role in the induction of vertebral skeleton demineralization. Different histological and histomorphometric methods were performed on vertebral samples of control and cortisoltreated eels. We demonstrated that cortisol induced a significant bone demineralization of eel vertebrae, as shown by significant decreases of the mineral ratio measured by incineration, and the degree of mineralization measured by quantitative microradiography of vertebral sections. Histology and image analysis of ultrathin microradiographs showed the induction by cortisol of different mechanisms of bone resorption, including periosteocytic osteolysis and osteoclastic resorption. Specificity of cortisol action was investigated by comparison with the effects of sex steroids. Whereas, testosterone had no effect, estradiol induced vertebral skeleton demineralization, an effect related to the stimulated synthesis of vitellogenin (Vg), an oviparous specific phospho-calciolipoprotein. By contrast, the cortisol demineralization effect was not related to any stimulation of Vg. This study demonstrates GC-induced bone demineralization in an adult non-mammalian vertebrate, which undergoes natural bone resorption during its life cycle. Our data suggest that the stimulatory action of cortisol on bone loss may represent an ancestral and conserved endocrine regulation in vertebrates.

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Section: Hormonal Treatmentmentioning

confidence: 99%

Section: Measurement Of Mineral Ratio By Incinerationmentioning

confidence: 99%

Section: Measurement Of Mineralization Degree By Quantitative Microramentioning

confidence: 99%

Section: Measurement Of Mineralization Degree By Quantitative Microramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cortisol mobilizes mineral stores from vertebral skeleton in the European eel: an ancestral origin for glucocorticoid-induced osteoporosis?

Sbaihi

Rousseau

Baloche

et al. 2009

Journal of Endocrinology

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Effects of Swimming on Silvering and Maturation of the European Eel, Anguilla anguilla L.

Palstra¹,

Ginneken²,

Thillart³

2009

Spawning Migration of the European Eel

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Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction

Palstra

Thillart

2010

Fish Physiol Biochem

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The European eel migrates 5,000–6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European eels are able to swim long distances at a cost of 10–12 mg fat/km which is 4–6 times more efficient than salmonids. The total energy costs of reproduction correspond to 67% of the fat stores. During long distance swimming, the body composition stays the same showing that energy consumption calculations cannot be based on fat alone but need to be compensated for protein oxidation. The optimal swimming speed is 0.61–0.67 m s−1, which is ~60% higher than the generally assumed cruise speed of 0.4 m s−1 and implies that female eels may reach the Sargasso Sea within 3.5 months instead of the assumed 6 months. Swimming trials showed lipid deposition and oocyte growth, which are the first steps of sexual maturation. To investigate effects of oceanic migration on maturation, we simulated group-wise migration in a large swim-gutter with seawater. These trials showed suppressed gonadotropin expression and vitellogenesis in females, while in contrast continued sexual maturation was observed in silver males. The induction of lipid deposition in the oocytes and the inhibition of vitellogenesis by swimming in females suggest a natural sequence of events quite different from artificial maturation protocols.

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Thyroid hormone-induced demineralisation of the vertebral skeleton of the eel, Anguilla anguilla

Cited by 27 publications

References 64 publications

Cortisol mobilizes mineral stores from vertebral skeleton in the European eel: an ancestral origin for glucocorticoid-induced osteoporosis?

Cortisol mobilizes mineral stores from vertebral skeleton in the European eel: an ancestral origin for glucocorticoid-induced osteoporosis?

Effects of Swimming on Silvering and Maturation of the European Eel, Anguilla anguilla L.

Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction

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