Disuse in adult male rats attenuates the bone anabolic response to a therapeutic dose of parathyroid hormone

2006 ◽  
Vol 101 (3) ◽  
pp. 881-886 ◽  
Author(s):  
Russell T. Turner ◽  
Sutada Lotinun ◽  
Theresa E. Hefferan ◽  
Emily Morey-Holton
Keyword(s):  
Parathyroid Hormone ◽  
Bone Formation ◽  
Cancellous Bone ◽  
Therapeutic Dose ◽  
Weight Bearing ◽  
Formation Rate ◽  
Hindlimb Unloading ◽  
Male Rats ◽  
Mineral Apposition Rate ◽  
Bone Formation Rate

Intermittent treatment with parathyroid hormone (PTH) increases bone formation and prevents bone loss in hindlimb-unloaded (HLU) rats. However, the mechanisms of action of PTH are incompletely known. To explore possible interactions between weight bearing and PTH, we treated 6-mo-old weight-bearing and HLU rats with a human therapeutic dose (1 μg·kg−1·day−1) of human PTH(1–34) (hPTH). Cortical and cancellous bone formation was measured in tibia at the diaphysis proximal to the tibia-fibula synostosis and at the proximal metaphysis, respectively. Two weeks of hindlimb unloading resulted in a dramatic decrease in the rate of bone formation at both skeletal sites, which was prevented by PTH treatment at the cancellous site only. In contrast, PTH treatment increased cortical as well as cancellous bone formation in weight-bearing rats. Two-way ANOVA revealed that hPTH and HLU had independent and opposite effects on all histomorphometric indexes of bone formation [mineral apposition rate (MAR), double-labeled perimeter (dLPm), and bone formation rate (BFR)] at both skeletal sites. The bone anabolic effects of weight bearing and hPTH on dLPm and BFR at the cortical site were additive, as were the effects on MAR at the cancellous site. In contrast, weight bearing and hPTH resulted in synergistic increases in cortical bone MAR and cancellous bone dLPm and BFR. We conclude that weight bearing and PTH act cooperatively to increase bone formation by resulting in site-specific additive and synergistic increases in indexes of osteoblast number and activity, suggesting that weight-bearing exercise targeted to osteopenic skeletal sites may improve the efficacy of PTH therapy for osteoporosis.

Bone and hormonal changes induced by skeletal unloading in the mature male rat

1999 ◽  
Vol 276 (1) ◽  
pp. E62-E69 ◽  
Author(s):  
Walter Dehority ◽  
Bernard P. Halloran ◽  
Daniel D. Bikle ◽  
Tracy Curren ◽  
Paul J. Kostenuik ◽  
...  
Keyword(s):  
Bone Formation ◽  
Weight Bearing ◽  
Formation Rate ◽  
Mineral Apposition Rate ◽  
Male Rat ◽  
Hormonal Changes ◽  
Bone Maturation ◽  
Bone Formation Rate ◽  
Gravitational Loading ◽  
Elevation Model

To determine whether the rat hindlimb elevation model can be used to study the effects of spaceflight and loss of gravitational loading on bone in the adult animal, and to examine the effects of age on bone responsiveness to mechanical loading, we studied 6-mo-old rats subjected to hindlimb elevation for up to 5 wk. Loss of weight bearing in the adult induced a mild hypercalcemia, diminished serum 1,25-dihydroxyvitamin D, decreased vertebral bone mass, and blunted the otherwise normal increase in femoral mass associated with bone maturation. Unloading decreased osteoblast numbers and reduced periosteal and cancellous bone formation but had no effect on bone resorption. Mineralizing surface, mineral apposition rate, and bone formation rate decreased during unloading. Our results demonstrate the utility of the adult rat hindlimb elevation model as a means of simulating the loss of gravitational loading on the skeleton, and they show that the effects of nonweight bearing are prolonged and have a greater relative effect on bone formation in the adult than in the young growing animal.

Effects of disrupted β1-integrin function on the skeletal response to short-term hindlimb unloading in mice

2005 ◽  
Vol 98 (2) ◽  
pp. 690-696 ◽  
Author(s):  
U. T. Iwaniec ◽  
T. J. Wronski ◽  
D. Amblard ◽  
Y. Nishimura ◽  
M. C. H. van der Meulen ◽  
...  
Keyword(s):  
Bone Formation ◽  
Cancellous Bone ◽  
Formation Rate ◽  
Dominant Negative ◽  
Hindlimb Unloading ◽  
Femoral Diaphysis ◽  
Short Term ◽  
Bone Formation Rate ◽  
Mechanical Unloading ◽  
Lumbar Vertebral Body

The study was designed to determine whether β1-integrin plays a role in mediating the acute skeletal response to mechanical unloading. Transgenic (TG) mice were generated to express a dominant negative form of β1-integrin under the control of the osteocalcin promoter, which targets expression of the transgene to mature osteoblasts. At 63 days of age, wild-type (WT) and TG mice were subjected to hindlimb unloading by tail suspension for 1 wk. Pair-fed, normally loaded WT and TG mice served as age-matched controls. Bone samples from each mouse were processed for quantitative bone histomorphometry and biomechanical testing. The skeletal phenotype of TG mice was characterized by lower cancellous bone mass in the distal femoral metaphysis (−52%) and lumbar vertebral body (−20%), reduced curvature of the proximal tibia (−20%), and decreased bone strength (−20%) and stiffness (−23%) of the femoral diaphysis with relatively normal indexes of cancellous bone turnover. Hindlimb unloading for only 1 wk induced a 10% decline in tibial curvature and a 30% loss of cancellous bone in the distal femur due to a combination of increased bone resorption and decreased bone formation in both WT and TG mice. However, the strength and stiffness of the femoral diaphysis were unaffected by short-term hindlimb unloading in both genotypes. The observed increase in osteoclast surface was greater in unloaded TG mice (92%) than in unloaded WT mice (52%). Cancellous bone formation rate was decreased in unloaded WT (−29%) and TG (−15%) mice, but, in contrast to osteoclast surface, the genotype by loading interaction was not statistically significant. The results indicate that altered integrin function in mature osteoblasts may enhance the osteoclastic response to mechanical unloading but that it does not have a major effect on the development of cancellous osteopenia in mice during the early stages of hindlimb unloading.

Human parathyroid hormone(1–34) increases bone formation and strength of cortical bone in aged rats

1994 ◽  
Vol 130 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Charlotte Ejersted ◽  
Troels T Andreassen ◽  
Magnus HL Nilsson ◽  
Hans Oxlund
Keyword(s):  
Parathyroid Hormone ◽  
Bone Formation ◽  
Cortical Bone ◽  
Formation Rate ◽  
The Body ◽  
Male Rats ◽  
Double Labelling ◽  
Aged Rats ◽  
Human Parathyroid Hormone ◽  
Bone Formation Rate

Ejersted C, Andreassen TT, Nilsson MHL, Oxlund H. Human parathyroid hormone(1–34) increases bone formation and strength of cortical bone in aged rats. Eur J Endocrinol 1994;130:201–7. ISSN 0804–4643 The effect of parathyroid hormone (PTH(1–34)) on mid-diaphyseal femoral cortical bone was studied in 2-year-old male rats. The rats were treated with daily injections of 1 5 nmol/kg PTH(1–34) or vehicle for 56 days, and labelled with tetracycline and calcein on day 15 and day 40, respectively. The PTH(1–34) treatment did not affect the body weights or the lengths of the femora. Fluorescence microscopy showed large intracortical cavities in the old vehicle-treated rats. After PTH treatment, double labelling and new bone formation filling in these cavities were found. Furthermore, an increased bone formation rate was observed both at the periosteum and at the endosteum. This resulted in an increase in the cross-sectional area and a decrease in the medullary area. Three-point bending analysis revealed an increase in ultimate load, ultimate stiffness, energy absorption and ultimate stress after the PTH(1–34) treatment. No differences were found between the groups regarding the hydroxyproline concentration or apparent and real densities. The ash concentration was, however, slightly reduced after PTH(1–34) treatment. The PTH(1–34) treatment of old rats induced the formation of bone both from the periosteum and endosteum, with a pronounced filling in of intracortical cavities, and, furthermore, a marked increase in the biomechanical competence of the cortical bone. Charlotte Ejersted, Department of Connective Tissue Biology, Institute of Anatomy, University of Aarhus, DK-8000 Aarhus C. Denmark

Dietary Calcium Supplementation Suppresses Bone Formation in Magnesium-Deficient Rats

2006 ◽  
Vol 76 (3) ◽  
pp. 111-116 ◽  
Author(s):  
Hiroshi Matsuzaki ◽  
Misao Miwa
Keyword(s):  
Bone Formation ◽  
Calcium Supplementation ◽  
Control Diet ◽  
Formation Rate ◽  
Dietary Calcium ◽  
Mineral Apposition Rate ◽  
Control Group ◽  
Deficient Diet ◽  
Bone Formation Rate ◽  
Male Wistar Rats

The purpose of this study was to clarify the effects of dietary calcium (Ca) supplementation on bone metabolism of magnesium (Mg)-deficient rats. Male Wistar rats were randomized by weight into three groups, and fed a control diet (control group), a Mg-deficient diet (Mg- group) or a Mg-deficient diet having twice the control Ca concentrations (Mg-2Ca group) for 14 days. Trabecular bone volume was significantly lower in the Mg - and Mg-2Ca groups than in the control group. Trabecular number was also significantly lower in the Mg - and Mg-2Ca groups than in the control group. Mineralizing bone surface, mineral apposition rate (MAR), and surface referent bone formation rate (BFR/BS) were significantly lower in the Mg - and Mg-2Ca groups than in the control group. Furthermore, MAR and BFR/BS were significantly lower in the Mg-2Ca group than in the Mg - group. These results suggest that dietary Ca supplementation suppresses bone formation in Mg-deficient rats.

Attenuated bone aluminum deposition in nonuremic beagles with reduced bone remodeling

1990 ◽  
Vol 258 (4) ◽  
pp. E576-E581
Author(s):  
L. D. Quarles
Keyword(s):  
Parathyroid Hormone ◽  
Bone Formation ◽  
Bone Turnover ◽  
Bone Remodeling ◽  
Aluminum Chloride ◽  
Formation Rate ◽  
Bone Formation Rate ◽  
Osteoid Surface ◽  
Aluminum Accumulation ◽  
Aluminum Deposition

Excess bone aluminum accumulates in uremic subjects after parathyroidectomy. To evaluate whether decreased bone remodeling caused by parathyroidectomy augments bone aluminum deposition, we administered aluminum chloride (0.75 mg/kg iv 3 times/wk) or vehicle to thyroparathyroidectomized (TPTX) and sham-operated (Sham) nonuremic beagles for 8 wk. TPTX alone effectively lowered plasma parathyroid hormone concentrations (8.2 +/- 2.8 vs. 27 +/- 2.2 pg/ml) and consequently suppressed bone remodeling, as evidenced by the diminished resorptive surface (0.8 +/- 0.3 vs. 4.0 +/- 0.5%), osteoid surface (0.5 +/- 0.2 vs. 13.3 +/- 2.3%), and bone formation rate (1.8 +/- 0.6 vs. 15.5 +/- 2.2%/yr) compared with untreated Shams. Aluminum treatment resulted in no further suppression of bone remodeling in TPTX dogs and did not cause osteomalacia. Aluminum-treated TPTX dogs, however, accumulated much less total bone (28.1 +/- 4.5 micrograms/g) and surface aluminum (3.8 +2- 1.4%) than similarly treated Shams (61.4 +/- 5.6 micrograms/g; 12.2 +/- 2.7%, respectively) despite displaying higher plasma aluminum concentrations (1,209 +/- 330 vs. 181 +/- 18 micrograms/l). These observations illustrate that diminished bone turnover retards rather than augments bone aluminum accumulation. Thus bone aluminum deposition after parathyroidectomy in uremic subjects is not likely to be the result of passive aluminum accumulation on inactive bone surfaces. Further studies are needed to determine whether factors, such as prior bone aluminum accumulation and/or the degree of preexistent hyperosteoidosis, modulate aluminum accumulation after parathyroidectomy.

The anabolic effect of 17β-oestradiol on the trabecular bone of adult rats is suppressed by indomethacin

1992 ◽  
Vol 133 (2) ◽  
pp. 189-195 ◽  
Author(s):  
J. W. M. Chow ◽  
J. M. Lean ◽  
T. Abe ◽  
T. J. Chambers
Keyword(s):  
Bone Formation ◽  
Trabecular Bone ◽  
Bone Growth ◽  
Formation Rate ◽  
Bone Volume ◽  
Female Rats ◽  
Mineral Apposition Rate ◽  
Adult Rats ◽  
Bone Formation Rate

ABSTRACT We have previously demonstrated that administration of oestrogen, at doses sufficient to raise serum concentrations to those seen in late pregnancy, increases trabecular bone formation in the metaphysis of adult rats. To determine whether prostaglandins (PGs), which have been shown to induce osteogenesis in vivo, play a role in the induction of bone formation by oestrogen, 13-week-old female rats were given daily doses of 4 mg 17β-oestradiol (OE2)/kg for 17 days, alone or with indomethacin (1 mg/kg). The rats were also given double fluorochrome labels and at the end of the experiment tibias were subjected to histomorphometric assessment. Treatment with OE2 suppressed longitudinal bone growth and increased uterine wet weight, as expected, and neither response was affected by indomethacin. Oestrogen also induced a threefold increase in trabecular bone formation in the proximal tibial metaphysis, which resulted in a substantial increase in trabecular bone volume. As previously observed, the increase in bone formation was predominantly due to an increase in osteoblast recruitment (as judged by an increase in the percentage of bone surface showing double fluorochrome labels), with only a minor increase in the activity of mature osteoblasts (as judged by the mineral apposition rate). Indomethacin abolished the increase in osteoblastic recruitment, but the activity of mature osteoblastic cells remained high. The bone formation rate and bone volume remained similar to controls. The results suggest that PG production may be necessary for the increased osteoblastic recruitment induced by oestrogen, but not to mediate the effects of oestrogen on the activity of mature osteoblasts. Journal of Endocrinology (1992) 133, 189–195

Effect of Minocycline on Osteoporosis

1998 ◽  
Vol 12 (1) ◽  
pp. 71-75 ◽  
Author(s):  
S. Williams ◽  
A. Wakisaka ◽  
Q.Q. Zeng ◽  
J. Barnes ◽  
S. Seyedin ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Formation Rate ◽  
Inhibitory Effect ◽  
Mineral Apposition Rate ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Trabecular Thickness ◽  
Trabecular Bone Area

The effect of oral minocycline on osteopenia in ovariectomized (OVX) old rats was examined in this study. Rats were divided into 4 groups: sham-operated, OVX followed by treatment with vehicle, minocycline, or 17β-estradiol. The treatment was initiated one day after OVX and proceeded for 8 wks. OVX reduced bone mineral density (BMD) in the whole femur and in the femoral regions that are enriched in trabecular bone. Treatment with minocycline or estrogen prevented a decrease in BMD. Femoral trabecular bone area, trabecular number, and trabecular thickness were reduced, and trabecular separation was increased by OVX. Treatment with minocycline or estrogen abolished the detrimental effects induced by OVX. OVX also reduced indices that reflect the interconnectivity of trabecular bone, and the loss of trabecular connectivity was prevented by treatment with minocycline or estrogen. Based on the levels of urinary pyridinoline, we showed that the effect of estrogen, but not minocycline, was primarily through its inhibitory effect on bone resorption. Analysis of bone turnover activity suggests that OVX increased parameters associated with bone resorption (eroded surface) and formation (osteoid surface, mineralizing surface, mineral apposition rate, and bone formation rate). Treatment with minocycline reduced bone resorption modestly and stimulated bone formation substantially. In contrast, treatment with estrogen drastically reduced parameters associated with both bone resorption and formation. We have concluded that oral minocycline can effectively prevent the decrease in BMD and trabecular bone through its dual effects on bone resorption and formation.

scholarly journals Palm Tocotrienol Supplementation Enhanced Bone Formation in Oestrogen-Deficient Rats

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ima Nirwana Soelaiman ◽  
Wang Ming ◽  
Roshayati Abu Bakar ◽  
Nursyahrina Atiqah Hashnan ◽  
Hanif Mohd Ali ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Type I Collagen ◽  
Formation Rate ◽  
Serum Levels ◽  
Female Rats ◽  
Mineral Apposition Rate ◽  
Type I ◽  
Bone Biomarkers ◽  
Bone Formation Rate

Postmenopausal osteoporosis is the commonest cause of osteoporosis. It is associated with increased free radical activity induced by the oestrogen-deficient state. Therefore, supplementation with palm-oil-derived tocotrienols, a potent antioxidant, should be able to prevent this bone loss. Our earlier studies have shown that tocotrienol was able to prevent and even reverse osteoporosis due to various factors, including oestrogen deficiency. In this study we compared the effects of supplementation with palm tocotrienol mixture or calcium on bone biomarkers and bone formation rate in ovariectomised (oestrogen-deficient) female rats. Our results showed that palm tocotrienols significantly increased bone formation in oestrogen-deficient rats, seen by increased double-labeled surface (dLS/Bs), reduced single-labeled surface (sLS/BS), increased mineralizing surface (MS/BS), increased mineral apposition rate (MAR), and an overall increase in bone formation rate (BFR/BS). These effects were not seen in the group supplemented with calcium. However, no significant changes were seen in the serum levels of the bone biomarkers, osteocalcin, and cross-linked C-telopeptide of type I collagen, CTX. In conclusion, palm tocotrienol is more effective than calcium in preventing oestrogen-deficient bone loss. Further studies are needed to determine the potential of tocotrienol as an antiosteoporotic agent.

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