In recent years, the intermittent, exogenous application of parathyroid hormone fragment has been established as a therapeutic agent for human osteoporosis. The present placebo-controlled trial evaluated the effects of intermittent, exogenous application of equine parathyroid hormone fragment (ePTH 1-37) on calcium homeostasis and bone metabolism in healthy horses. The dose-response relationship and an appropriate daily treatment scheme with ePTH (1-37) were assessed with 0.5, 1, 5, 10, and 40 µg ePTH (1-37)/kg BW to provide a basis for long-term ePTH (1-37) application. The dose selection of 0.5 µg ePTH (1-37)/kg KM for long-term application resulted from a short, temporary increase in the ionized blood calcium level after ePTH (1-37) injection and an unimpaired fractional calcium and phosphorus excretion. Higher dosages caused adverse events such as persisting hypercalcemia and general condition disturbance after 2 or 3 days of treatment. In a subsequent attempt, 6 horses each received either ePTH (1-37) or placebo for 120 days by daily subcutaneous injections. The diurnal response of calcium in blood reflected the responsiveness of the target cells to exogenous application of ePTH (1-37). During the observation period, cancellous bone mineral density increased significantly, but showed no differences between ePTH treatment and placebo. After long-term application, parathyroid response and endogenous intact parathyroid hormone release were investigated using Na2EDTA-induced hypocalcemia. Previously ePTH-treated horses showed moderately reduced levels of endogenous intact PTH when compared to those results obtained in the placebo group. Concomitant, ePTH-treated horses appeared to have a more rapid and improverd recovery of calcium homeostasis. In general, the long-term intermittent application of 0.5 µg ePTH (1-37)/kg BW seemed to have no negative effects in healthy horses. The potential area of ePTH application in horses could be osteoporotic stages, for instance, as observed in podotrochlosis and glucocorticoid-induced bone loss.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:15-20091109-094313-9 |
| Date | 09 November 2009 |
| Creators | Weisrock, Katharina Uta |
| Contributors | Universität Leipzig, Veterinärmedizinische Fakultät |
| Publisher | Universitätsbibliothek Leipzig |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | deu |
| Detected Language | English |
| Type | doc-type:doctoralThesis |
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