Effects of the (1-34) fragment of synthetic parathyroid hormone-related protein on tartrate-resistant acid phosphatase and alkaline phosphatase and alkaline phosphatase activities, and on osteocalcin synthesis, in cultured fetal rat calvaria.
In the last years, a parathyroid hormone (PTH)-related peptide (PTHrP) has been isolated from tumors associated with humoral hypercalcemia with malignancy (HHM). In the present work, we studied the effect of bovine PTH (bPTH)(1-34) and PTHrP(1-34) on tartrate-resistant acid phosphatase (TRAP), a marker of bone resorption, and alkaline phosphatase (AP) activities, and basal and vitamin D-stimulated osteocalcin (BGP) synthesis (markers of bone formation) in fetal rat calvaria cultures. After a 48-hour incubation period, both bPTH(1-34) and PTHrP(1-34) caused an increase in TRAP activity liberated in the medium with respect to control cultured calvaria. On the other hand, while after 2 or 4 h of incubation both bPTH(1-34) and PTHrP(1-34) caused a decrease in the AP activity liberated in the medium, after 48 h of incubation both peptides caused a significant increase in the AP liberated in the medium with respect to control cultures. With respect to BGP synthesis, both bPTH(1-34) and PTHrP(1-34) antagonized the 1,25-dihydroxyvitamin D3 stimulatory effect in calvaria cultures. We conclude that PTHrP(1-34) causes similar effects on bone, in organ cultures, to those caused by bPTH(1-34), namely an increase in both bone resorption and formation and a decrease in the vitamin D-stimulated BGP synthesis.
Laboratorio de la Unidad Metabólica, Fundación Jimenez Díaz, Madrid, España.
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D000135:Acid Phosphatase / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology; D002478:Cells, Cultured; D015675:Osteocalcin / Q000096:biosynthesis*; D010281:Parathyroid Hormone / Q000494:pharmacology; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000494:pharmacology*; D011506:Proteins / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013644:Tartrates / Q000494:pharmacology; D013997:Time Factors
D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; D013644:Tartrates; D015675:Osteocalcin; C025076:parathyroid hormone (1-34), bovine; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D002117:Calcitriol; C029768:tartaric acid