A PTH/PTHrP receptor antagonist blocks the hypercalcemic response to estradiol-17beta. | - CCMAR -

Journal Article

TítuloA PTH/PTHrP receptor antagonist blocks the hypercalcemic response to estradiol-17beta.
Publication TypeJournal Article
AuthorsFuentes, J, Guerreiro, PM, Modesto, T, Rotllant, J, Canario, AVM, Power, DM
Year of Publication2007
JournalAm J Physiol Regul Integr Comp Physiol
Date Published2007 Aug
Palavras-chaveAnimals, Calcium, Drug Interactions, Estradiol, Homeostasis, Hypercalcemia, Injections, Intraperitoneal, Parathyroid Hormone, Parathyroid Hormone-Related Protein, Peptide Fragments, Phosphates, Proteins, Receptor, Parathyroid Hormone, Type 1, Sea Bream

Estradiol (E(2)) increases circulating calcium and phosphate levels in fish, thus acting as a hypercalcemic and hyperphosphatemic factor during periods of high calcium requirements, such as during vitellogenesis. Since parathyroid hormone (PTH)-related protein (PTHrP) has been shown to be calciotropic in fish, we hypothesized that the two hormones could be mediating the same process. Sea bream (Sparus auratus) juveniles receiving a single intraperitoneal injection of piscine PTHrP(1-34) showed an elevation in calcium plasma levels within 24 h. In contrast, injections of the PTH/PTHrP receptor antagonist PTHrP(7-34) decreased circulating levels of calcium in the same period. Intraperitoneal implants of estradiol-17beta (E(2); 10 microg/g) evoked significant increases of circulating plasma levels of calcium and phosphorus and a sustained increases of circulating plasma levels of PTHrP. However, a combined treatment of E(2) and PTHrP(7-34) evoked a markedly lower calcium response compared with E(2) alone. We conclude that PTHrP or a related peptide that binds the PTH/PTHrP receptor mediates, at least in part, the hypercalcemic effect of E(2) in calcium and phosphate balance in fish.



Alternate JournalAm. J. Physiol. Regul. Integr. Comp. Physiol.
PubMed ID17537843