Actions of calcitonin, parathyroid hormone, and prostaglandin E2 on cyclic AMP formation in chicken and rat osteoclasts

1986 ◽  
Vol 31 (3) ◽  
pp. 229-241 ◽  
Author(s):  
G. C. Nicholson ◽  
S. A. Livesey ◽  
J. M. Moseley ◽  
T. J. Martin
1981 ◽  
Vol 33 (1) ◽  
pp. 641-648 ◽  
Author(s):  
Curtis L. Parker ◽  
David M. Biddulph ◽  
Timothy A. Ballard

1990 ◽  
Vol 10 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Östen Ljunggren ◽  
Jan Rosenquist ◽  
Maria Ransjö ◽  
Ulf H. Lerner

The effect of bradykinin on prostaglandin E2 formation in cells from human trabecular bone has been studied. The cells responded to parathyroid hormone with enhanced cyclic AMP formation and were growing as cuboidal-shaped, osteoblast-like cells. In these isolated human osteoblast-like cells, bradykinin (1 μmol/l) caused a rapid (5 min) stimulation of prostaglandin E2 formation. This finding indicates that human osteoblasts are equipped with receptors for bradykinin linked to an increase in prostaglandin formation.


1988 ◽  
Vol 252 (1) ◽  
pp. 263-268 ◽  
Author(s):  
R W Farndale ◽  
J R Sandy ◽  
S J Atkinson ◽  
S R Pennington ◽  
S Meghji ◽  
...  

Parathyroid hormone (PTH) and prostaglandin E2 (PGE2) are physiological agonists which stimulate bone cells to resorb bone, a process by which the mineralized extracellular bone matrix is dissolved. Bone resorption has a key role in the maintenance of plasma calcium levels. It has been established that both PTH and PGE2 activate adenylate cyclase in osteoblasts, but it is apparent that (1) the two agents have qualitatively different effects on osteoblasts, and (2) the generation of cyclic AMP cannot account for all the effects of PTH on bone cell metabolism. Others have demonstrated that PTH and PGE2 may also elevate intracellular calcium levels, but the mechanism by which this is achieved has not been fully defined. Here we have investigated the effects of PTH on neonatal mouse osteoblasts in culture and shown that physiological concentrations of the hormone (50 nM) caused a small increase (22%) in total inositol phosphates accumulation, with a larger increase (40%) in inositol trisphosphate. We found that this activation occurred at lower concentration than was necessary to activate adenylate cyclase. PGE2 was a more effective activator of inositol phosphates accumulation than PTH, causing up to 300% increase in the total inositol phosphates after 30 min. Both PTH and PGE2 stimulated cyclic AMP accumulation, but the activation of adenylate cyclase by forskolin did not enhance inositol phosphates production. We conclude that both PTH and PGE2 stimulate phosphoinositide turnover in mouse osteoblasts and suggest that this mechanism may contribute to their elevation of intracellular calcium in bone cells.


1980 ◽  
Vol 93 (3) ◽  
pp. 339-345 ◽  
Author(s):  
Naokazu Nagata ◽  
Yuriko Ono ◽  
Narimichi Kimura

Abstract. The interaction between parathyroid hormone (PTH) and prostaglandin E1 (PGE1) in influencing cyclic AMP metabolism in rat renal cortical tissue was examined. PTH and PGE1 stimulated additively the adenylate cyclase activity in the homogenate of the tissue. Both PTH and PGE1 enhanced the level of cyclic AMP in the incubated renal cortical tissue, but the effect of their simultaneous addition did not exceed the effect induced by PTH alone. Cyclic AMP accumulated in the incubation medium by stimulation by PTH was decreased by the simultaneous addition of PGE1. When the tissue was pre-incubated for 30 min with 2 to 10 μg/ml of PGE1, the magnitude of the increase of cyclic AMP caused by PTH subsequently added was lessened. However, the response to PTH of adenylate cyclase preparation obtained from the homogenate of PGE1-pre-treated tissue was not decreased. When first PTH was added to the incubating renal cortical tissue, the subsequent addition of PGE1 accelerated the decrease of cyclic AMP content in the tissue and decreased the amount of cyclic AMP released from the tissue. The interaction of PTH and PGE1 on cyclic AMP metabolism in the renal cortical tissue was in contrast to that seen in newborn rat calvaria where PGE1 and PTH acted additively in enhancing the level of cyclic AMP.


1980 ◽  
Vol 67 (3) ◽  
pp. 471-475 ◽  
Author(s):  
I. Lewin ◽  
S. Tomlinson ◽  
G.N. Hendy ◽  
J.L.H. O'Riordan ◽  
D.W. Pickard ◽  
...  

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