Effects of forskolin on bone in organ culture

1987 ◽  
Vol 252 (1) ◽  
pp. E44-E48
Author(s):  
N. S. Krieger ◽  
P. H. Stern
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Calcium Release ◽  
Dependent Manner ◽  
Bone Culture ◽  
Length Of Treatment ◽  
Fetal Rat ◽  
Neonatal Mouse Calvaria ◽  
Dose Dependent

The effects of forskolin, which directly activates adenylate cyclase in most systems, have been compared with the actions of parathyroid hormone and calcitonin, both of which have been suggested to utilize cAMP as a second messenger in their actions on bone. Forskolin alone stimulated calcium release from neonatal mouse calvaria and fetal rat limb bones in vitro in a dose-dependent manner. The effect was maximal at 10(-6) M in both systems. At higher concentrations forskolin completely inhibited stimulated bone resorption, although with submaximal concentrations the inhibition was only partially sustained up to 72 h. Forskolin directly stimulated cAMP release from calvaria into the medium at concentrations up to 10(-4) M. Forskolin had no effect on the interaction between parathyroid hormone and calcitonin, while calcitonin inhibited the stimulatory effect of forskolin comparably with its inhibition of parathyroid hormone-stimulated bone resorption. The results indicate that forskolin has dual effects on bone and can mimic responses of both parathyroid hormone and calcitonin in both bone culture systems. The observed response depends on the concentration of forskolin used and the length of treatment with the drug.

scholarly journals Stimulation of cell proliferation in skeletal tissues of the rat by defined parathyroid hormone fragments

1991 ◽  
Vol 277 (3) ◽  
pp. 863-868 ◽  
Author(s):  
D Sömjen ◽  
K D Schlüter ◽  
E Wingender ◽  
H Mayer ◽  
A M Kaye
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Thymidine Incorporation ◽  
Specific Activity ◽  
Fold Increase ◽  
Dependent Manner ◽  
Equimolar Concentration ◽  
Dose Dependent

We have found, in previous studies in vitro using skeletal derived cell cultures, that mid-region fragments of human parathyroid hormone (hPTH) stimulate [3H]thymidine incorporation into DNA and increase the specific activity of the brain-type isoenzyme of creatine kinase (CK). These changes occurred without an increase in cyclic AMP formation which is linked to bone resorption. In this study, we found that the mid-region fragment hPTH-(28-48) stimulated CK activity in diaphysis, epiphysis and kidney in a time- and dose-dependent manner, parallel to the effects of the whole molecule bovine (b)PTH-(1-84) and the fully active fragment hPTH-(1-34). The increase caused by hPTH-(28-48) at a dose of 1.25 micrograms/rat was not less than the 2-fold increase caused by a roughly equimolar concentration bPTH-(1-84). A significant increase was reached at 1 h after intraperitoneal injection in all cases. All three sequences of PTH caused an increase in [3H]thymidine incorporation into DNA in diaphysis and epiphysis, but not in kidney, 24 h after injection. A fragment further towards the C-terminal, hPTH-(34-47), was inactive compared with an equimolar concentration of the fragment hPTH-(25-39), which stimulated both CK activity and DNA synthesis. These results in vivo are in line with previous findings in vitro; they provide further support for the suggestion that mid-region fragments of the PTH molecule could be used to induce bone formation without incurring the deleterious effect of bone resorption.

Interaction between amrinone and parathyroid hormone on bone in culture

1982 ◽  
Vol 243 (6) ◽  
pp. E499-E504
Author(s):  
N. S. Krieger ◽  
P. H. Stern
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Direct Interaction ◽  
Inhibitory Effects ◽  
Dihydroxyvitamin D3 ◽  
Basal Bone ◽  
Cardiotonic Agent ◽  
Neonatal Mouse Calvaria ◽  
Dose Dependent ◽  
Stimulation Of

The cardiotonic agent amrinone has been postulated to directly affect Na-Ca exchange. Because stimulated bone resorption has been proposed to require Na-Ca exchange, we examined the effects of amrinone on bone. Amrinone inhibited release of Ca from neonatal mouse calvaria in organ culture stimulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin d3, or prostaglandin E2. Inhibition was dose dependent and maximal at 2 X 10(-4) M. The effect of amrinone differed from the inhibitory effects of calcitonin, ouabain, or nigericin in that 1) 6-h exposure to amrinone alone prevented the effect of subsequently added PTH; 2) amrinone was only partially effective if added after resorption was initiated by 24-h treatment with PTH; 3) coincubation with amrinone and PTH during the first 48 h of culture allowed for a response to PTH after amrinone was removed; no such protection by a stimulator occurred with ouabain or nigericin. Also submaximal concentrations of amrinone plus calcitonin, ouabain, or nigericin gave greater than additive inhibition of Ca release. Amrinone had no effect on basal bone cAMP or on the acute stimulation of cAMP by PTH. The results suggest that amrinone could have a more direct interaction with the pathway involved in stimulated bone resorption than the other inhibitors.

scholarly journals Lumican Inhibits Osteoclastogenesis and Bone Resorption by Suppressing Akt Activity

2021 ◽  
Vol 22 (9) ◽  
pp. 4717
Author(s):  
Jin-Young Lee ◽  
Da-Ae Kim ◽  
Eun-Young Kim ◽  
Eun-Ju Chang ◽  
So-Jeong Park ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Map Kinases ◽  
Osteoclast Differentiation ◽  
Dependent Manner ◽  
Dual Action ◽  
Dose Dependent ◽  
Resorptive Activity

Lumican, a ubiquitously expressed small leucine-rich proteoglycan, has been utilized in diverse biological functions. Recent experiments demonstrated that lumican stimulates preosteoblast viability and differentiation, leading to bone formation. To further understand the role of lumican in bone metabolism, we investigated its effects on osteoclast biology. Lumican inhibited both osteoclast differentiation and in vitro bone resorption in a dose-dependent manner. Consistent with this, lumican markedly decreased the expression of osteoclastogenesis markers. Moreover, the migration and fusion of preosteoclasts and the resorptive activity per osteoclast were significantly reduced in the presence of lumican, indicating that this protein affects most stages of osteoclastogenesis. Among RANKL-dependent pathways, lumican inhibited Akt but not MAP kinases such as JNK, p38, and ERK. Importantly, co-treatment with an Akt activator almost completely reversed the effect of lumican on osteoclast differentiation. Taken together, our findings revealed that lumican inhibits osteoclastogenesis by suppressing Akt activity. Thus, lumican plays an osteoprotective role by simultaneously increasing bone formation and decreasing bone resorption, suggesting that it represents a dual-action therapeutic target for osteoporosis.

Effects of ammonium chloride on resorption of fetal rat bones in organ culture

1984 ◽  
Vol 246 (6) ◽  
pp. E516-E518
Author(s):  
A. J. Johannesson ◽  
L. G. Raisz
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Organ Culture ◽  
Ammonium Chloride ◽  
Lysosomal Enzyme ◽  
Potent Inhibitor ◽  
Lysosomal Function ◽  
Fetal Rat ◽  
45Ca Release

Ammonium chloride, a known inhibitor of lysosomal function, was found to be a rapid and potent inhibitor of 45Ca release from fetal rat bones in organ culture. The response to parathyroid hormone and prostaglandin E2 was inhibited in a dose-related, reversible fashion. The activity of the lysosomal enzyme beta-glucuronidase in the medium closely paralleled 45Ca release. Ammonium chloride may now be added to the list of antilysosomal agents that inhibit bone resorption in vitro.

scholarly journals Rainbow trout hypocalcin stimulates bone resorption in embryonic mouse calvaria in vitro in a PTH-like fashion

1989 ◽  
Vol 143 (1) ◽  
pp. 165-175
Author(s):  
F. P. Lafeber ◽  
M. P. Herrmann-Erlee ◽  
G. Flik ◽  
S. E. Wendelaar Bonga
Keyword(s):  
Bone Resorption ◽  
Cyclic Amp ◽  
Tertiary Structure ◽  
Lactate Production ◽  
Dependent Manner ◽  
Embryonic Mouse ◽  
Molar Basis ◽  
Mouse Calvaria ◽  
Dose Dependent

Hypocalcin, the major hormone with hypocalcaemic action in fish, was isolated from trout corpuscles of Stannius (SCs). The bioactivity of hypocalcin was assessed in a parathyroid hormone (PTH) bioassay involving bone resorption in embryonic mouse calvaria. Calcium and phosphate release and lactate production were stimulated in a dose-dependent manner by hypocalcin. On a molar basis about equal amounts of hypocalcin and PTH were required to obtain similar effects in this assay. Hypocalcin did not stimulate cyclic AMP production either in mouse calvaria or in cultured osteoblasts. In this respect hypocalcin resembles shortened or N-terminus-modified PTH molecules that induce bone resorption without increasing cyclic AMP levels. Since hypocalcin and PTH have comparable bioactivity in this mammalian bioassay (as well as in fish bioassays), we tentatively suggest that both hormones are structurally similar and that both hormones may act via the same receptors. The two hormones show no resemblance to one another in primary structure, so we suggest that they have similarities in tertiary structure.

Adrenomedullin is a potent stimulator of osteoblastic activity in vitro and in vivo

1997 ◽  
Vol 273 (6) ◽  
pp. E1113-E1120 ◽  
Author(s):  
Jillian Cornish ◽  
Karen E. Callon ◽  
David H. Coy ◽  
Ning-Yi Jiang ◽  
Liqun Xiao ◽  
...  
Keyword(s):  
Thymidine Incorporation ◽  
Cell Number ◽  
Osteoblastic Activity ◽  
Adult Mice ◽  
Fetal Rat ◽  
Neonatal Mouse Calvaria ◽  
Dose Dependent Increase ◽  
Dose Dependent

Adrenomedullin is a 52-amino acid vasodilator peptide produced in many tissues, including bone. It has 20% sequence identity with amylin, a regulator of osteoblast growth, and circulates in picomolar concentrations. The present study assesses whether adrenomedullin also acts on osteoblasts. At concentrations of 10−12 M and greater, adrenomedullin produced a dose-dependent increase in cell number and [3H]thymidine incorporation in cultures of fetal rat osteoblasts. This effect was also seen with adrenomedullin-(15—52), -(22—52), and -(27—52), but adrenomedullin-(40—52) was inactive. These effects were lost in the presence of amylin blockers, suggesting they were mediated by the amylin receptor. Adrenomedullin also increased [3H]thymidine incorporation into cultured neonatal mouse calvaria but, unlike amylin, did not reduce bone resorption in this model. Adrenomedullin stimulated phenylalanine incorporation into both isolated osteoblasts and calvaria. When injected daily for 5 days over the calvariae of adult mice, it increased indexes of bone formation two- to threefold ( P < 0.0001) and increased mineralized bone area by 14% ( P = 0.004). It is concluded that adrenomedullin regulates osteoblast function and that it increases bone mass in vivo. The potential of this family of peptides in the therapy of osteoporosis should be further evaluated.

scholarly journals Regulation of ATP-induced calcium release in COS-7 cells by calcineurin

2000 ◽  
Vol 348 (1) ◽  
pp. 173-181 ◽  
Author(s):  
Arun BANDYOPADHYAY ◽  
Dong-Wook SHIN ◽  
Do Han KIM
Keyword(s):  
Mammalian Cells ◽  
Calcium Release ◽  
Calcineurin Inhibitors ◽  
Dependent Manner ◽  
Transfected Cells ◽  
High Level ◽  
Dose Dependent ◽  
Constitutively Active

Experiments were conducted to examine the role of calcineurin in regulating Ca2+ fluxes in mammalian cells. In COS-7 cells, increasing concentrations (1-10 μM) of ATP triggered intracellular Ca2+ release in a dose-dependent manner. Treatment of the cells with calcineurin inhibitors such as cyclosporin A (CsA), deltamethrin and FK506 resulted in an enhancement of ATP-induced intracellular Ca2+ release. Measurement of calcineurin-specific phosphatase activity in vitro demonstrated a high level of endogenous calcineurin activities in COS-7 cells, which was effectively inhibited by the addition of deltamethrin or CsA. The expression of constitutively active calcineurin (CnA∆CaMAI) inhibited the ATP-induced increase in intracellular Ca2+ concentration ([Ca2+]i), in both the presence and the absence of extracellular Ca2+. These results suggest that the constitutively active calcineurin prevented Ca2+ release from the intracellular stores. In the calcineurin-transfected cells, treatment with CsA restored the calcineurin-mediated inhibition of intracellular Ca2+ release. Protein kinase C-mediated phosphorylation of Ins(1,4,5)P3 receptor [Ins(1,4,5)P3R] was partly inhibited by the extracts prepared from the vector-transfected cells and completely inhibited by those from cells co-transfected with CnA∆CaMAI and calcineurin B. On the addition of 10 μM CsA, the inhibited phosphorylation of Ins(1,4,5)P3R was restored in both the vector-transfected cells and the calcineurin-transfected cells. These results show direct evidence that Ca2+ release through Ins(1,4,5)P3R in COS-7 cells is regulated by calcineurin-mediated dephosphorylation.

Effect of parathyroid hormone and calcitonin on the cytoplasmic spreading of isolated osteoclasts

1984 ◽  
Vol 102 (3) ◽  
pp. 281-286 ◽  
Author(s):  
T. J. Chambers ◽  
N. A. Athanasou ◽  
K. Fuller
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Salmon Calcitonin ◽  
Cell Types ◽  
Significant Inhibition ◽  
Neonatal Rat ◽  
Dependent Manner ◽  
Dose Dependent ◽  
Primary Action ◽  
Rat Bone

ABSTRACT Osteoclasts, the major agents of bone resorption, were isolated from neonatal rat bone, and the cytoplasmic spreading of these cells was measured after incubation in the presence or absence of hormones or other cell types. Salmon calcitonin, which inhibits osteoclastic bone resorption, reduced spreading in a dose-dependent manner and caused significant inhibition at concentrations as low as 6·7 pg/ml. Parathyroid hormone (PTH) had no effect on the spreading of isolated osteoclasts but if osteoblasts and osteoclasts were co-cultured the addition of PTH caused a marked increase in spreading at concentrations of 0·025 i.u./ml and above. The results suggest that while calcitonin is a direct inhibitor of osteoclastic activity, PTH may stimulate osteoclasts through a primary action on osteoblasts. J. Endocr. (1984) 102, 281–286

scholarly journals DIHYDROTESTOSTERONE DOWNREGULATES BONE RESORPTION ACTIVITY OF OSTEOCLASTS IN DOSE DEPENDENT MANNER: AN IN VITRO MODEL USING RAW 264.7 CELLS

2017 ◽  
Vol 9 (10) ◽  
pp. 86
Author(s):  
Hnin Ei Thu ◽  
Zahid Hussain ◽  
Isa Naina Mohamed ◽  
Ahmad Nazrun Shuid
Keyword(s):  
Bone Resorption ◽  
Cathepsin K ◽  
Raw 264.7 Cells ◽  
Tartrate Resistant Acid Phosphatase ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Sod Activity ◽  
Osteoclastic Differentiation ◽  
Dose Dependent

Objective: Numerous studies have evidenced the bone regulatory potential of dihydrotestosterone in androgen-deficient osteoporosis. The present study was thus aimed to explore the translational mechanism of dihydrotestosterone to down-regulate the bone resorption activity of osteoclasts using RAW 264.7 cells as in vitro model.Methods: Prior to analyze the efficacy of dihydrotestosterone (5α-DHT) to alleviate osteoclastic differentiation, their cell viability and cell proliferative ability was assessed using lactate dehydrogenase (LDH) and MTS assays. The osteoclastic differentiation capacity of dihydrotestosterone was evaluated by measuring TRAP activity and the expression of bone resorption-related proteins such as matrix metallopeptidase-9 (MMP-9), cathepsin-K, tartrate-resistant acid phosphatase (TRAP) and NFATc1. Moreover, the effects of dihydrotestosterone were also evaluated on superoxide (free radicals) generation and superoxide dismutase (SOD) activity in RANKL-induced osteoclasts.Results: Dihydrotestosterone showed no toxicity towards RAW 264.7 cells and significantly enhanced their proliferation and growth rates in a dose-dependent fashion. It was also observed that dihydrotestosterone exhibits a remarkable inhibitory effect on differentiation, maturation and activation of osteoclasts. The marked inhibition of differentiation and activation of osteoclasts caused by 5α-DHT was due to down-regulation of the expression of MMP-9, cathepsin-K, TRAP, NFATc1, generation of superoxide and up-regulation of SOD activity in the RAW 264.7 cells.Conclusion: Resulting data provided substantially in vitroevidence for the pronounced anti-osteoclastogenetic activity of dihydrotestosterone and its therapeutic value in treating osteoporosis and other bone-erosive disorders. 

Central actions of parathyroid hormone on blood calcium and hypothalamic neuronal activity in the rat

1995 ◽  
Vol 268 (1) ◽  
pp. R21-R27 ◽  
Author(s):  
H. Matsui ◽  
S. Aou ◽  
J. Ma ◽  
T. Hori
Keyword(s):  
Parathyroid Hormone ◽  
Neuronal Activity ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Blood Calcium ◽  
Bath Application ◽  
Central Actions ◽  
Dose Dependent ◽  
Postsynaptic Mechanism

The central actions of parathyroid hormone (PTH) on the blood ionized calcium level in anesthetized rats and the neuronal activity of the ventromedial nucleus of the hypothalamus (VMH) in vitro were investigated. An intracerebroventricular injection of PTH (0.01, 0.1, and 1 microgram) prevented urethan-induced hypocalcemia in a dose-dependent manner, whereas either an intravenous or an intracisternal injection of PTH (1 microgram) was ineffective. Eighty-three of 177 VMH neurons responded to a bath application of PTH (10(-7) or 3 x 10(-7) M): a majority (72, 83%) of the responsive cells decreased, whereas 11 increased their activity. This inhibitory effect of PTH on neuronal activity still persisted after synaptic blocking in a Ca(2+)-free/high-Mg2+ medium. A PTH receptor antagonist, [Tyr34]bPTH-(7-34)-NH2, suppressed the effect of PTH on the neuronal activity. These findings thus suggest that brain PTH has a calciotropic function and that one of the possible target sites is the VMH, where PTH inhibits its neuronal activity through a postsynaptic mechanism mediated by PTH receptors.

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