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Parathyroid hormone-related peptide and vitamin D in phosphocalcic metabolism for dromedary camel

El Khasmi M., Faye B.. 2011. Iranian Journal of Applied Animal Science, 1 (4) : p. 205-213.

In mammals, phosphocalcic and bone metabolisms are mainly regulated by parathyroïd hormone, parathyroïd hormone-related peptide (PTHrP) and 1[alpha],25-dihydroxyvitamin D or calcitriol. In camels, circulating levels of calcitriol are 10 times higher than those determined in other ruminants and further increase during early lactation. Calcitriol and parathyroïd-related peptide stimulate intestinal absorption of calcium and phosphorus, and phosphocalcic excretion by the mammary glands to maintain breast milk production in the same species. These endocrinian features allow, on one hand to improve the uptake of calcium and phosphorus in the adult, and on the other, to meet the phosphocalcic needs during growth and development of the young calf, in a precarious medium. In camels, the status of vitamin D varies with the season and the postpartum stage. Hypocalcemia and hypophosphatemia due to a deficiency of vitamin D are responsible for many bone disorders which could be corrected by a diet rich in calcium, phosphorus and vitamin D. The physiological peculiarities of the camel in relation to its particular mineral metabolism were largely reported by several authors (Faye and Bengoumi, 2000). These peculiarities show clearly the adaptation of the animal to a climatic and nutritional biotope which is marked by scarcity of water, and relatively low nutritional value of pasture resources. On major minerals, calcium (Ca) and phosphorus (P) are particularly essential for bone growth of young and milk production. In camel, milk is the only source of minerals for the calf until weaning which is still very late (up to 12 months) in this species and within the traditional farming. In camels, fundamental and applied investigations were performed on mineral metabolism endocrine regulation that involves among other factors, parathyroid hormone (PTH), PTH-related peptide (PTHrP or parathyroid hormone related peptide) and active vitamin D. The results of the work so far, seem to emphasize again the power of the camel to withstand arid and semi arid areas. This article proposes a synthesis of current knowledge about the camel and discusses them in light of those obtained in other domestic ruminants. PTH and PTHrP. In mammals, PTH is the major regulator peptide of Ca homeostasis. Produced almost exclusively by the parathyroid cells, PTH stimulates the release of Ca, phosphate and collagen in bone. The kidney responds to PTH by Ca reabsorption, phosphate excretion and synthesis. (Résumé d'auteur)

Mots-clés : parathyroïde; peptide; hormone; métabolisme; calcium; glande mammaire; endocrinologie; dromadaire; iran république islamique

Thématique : Physiologie et biochimie animales

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