The effect of calcium intake on bone composition and bone resorption in the young growing rat

A low Ca intake by both rats and man increases bone resorption, decreases bone mass and increases the risk of osteoporosis. The skeletal effect of high Ca intakes is less clear, particularly during periods of bone mineral accrual. Twenty-four female 5-week-old rats, Wistar strain, were randomized by weight into three groups of eight rats each and fedad libituma semi-purified diet containing 2 (Ca-restricted), 5 (normal) or 20 (Ca-supplemented) g Ca/kg for 3 weeks. When compared with the normal Ca diet, urinary Ca excretion was unaffected by the dietary restriction of Ca for 3 weeks, but was greater (P<0·001) in Ca-supplemented rats. Urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr) levels were significantly greater during weeks 2 (PyrP<0·05, DpyrP<0·001) and 3 (PyrP<0·01, Dpyr,P<0·001) of dietary Ca restriction, but were unaffected by Ca supplementation. Femoral dry weight and the concentration of Mg and P in femora were unaffected by dietary Ca concentration. Femoral Ca concentration was reduced (P<0·05) in the Ca-restricted group compared with the other two groups. In conclusion, these results suggest that increasing dietary Ca intake, well above the recommended level, had no effect on bone mineral composition or bone resorption (as assessed with urinary pyridinium crosslinks) in young growing female rats. In addition, these results confirm the findings of previous studies which have shown that bone Ca content in young growing rats was reduced by dietary Ca restriction and that this reduction results, at least in part, from an increased rate of bone resorption.

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The effect of moderately and severely restricted dietary magnesium intakes on bone composition and bone metabolism in the rat

British Journal Of Nutrition ◽

10.1017/s0007114599001130 ◽

1999 ◽

Vol 82 (1) ◽

pp. 63-71 ◽

Cited By ~ 57

Author(s):

Annette Creedon ◽

Albert Flynn ◽

Kevin Cashman

Keyword(s):

Bone Resorption ◽

Bone Formation ◽

Bone Development ◽

Dry Weight ◽

Male Rats ◽

Average Weight ◽

Mrna Levels ◽

Adequate Diet ◽

Wistar Strain ◽

Restricted Group

Forty 3-week-old male rats, Wistar strain, average weight 59 g, were randomized by weight into five groups of eight rats each. Three groups were fedad libitumon a semi-purified diet containing (per kg) 400 (adequate), 200 (moderately Mg-restricted) or 20 (severely Mg-restricted) mg Mg for 3 weeks while two groups were pair-fed with the Mg-adequate diet in the same quantities as those consumed by the two Mg-restricted groups respectively. While weight gains and food conversion efficiency values for the Mg-restricted groups were similar to those of the corresponding pair-fed control groups, serum and kidney Mg, and femoral dry weight were reduced by 70, 7 and 9 % respectively in the severely Mg-restricted group and were unaffected in the moderately Mg-restricted group. Significant reductions were observed in urinary pyridinoline (Pyr) (by 44 and 34 %) and deoxypyridinoline (Dpyr) levels (by 40 and 33 %) (markers of bone resorption), serum osteocalcin levels (by 46 and 28 %) (marker of bone formation), femoral Mg levels (by 52 and 14 %) and osteocalcin mRNA levels (by 46 and 22 %) compared with the corresponding pair-fed controls, in the severely and moderately Mg-restricted groups respectively, and these reductions, except for those in urinary Pyr and Dpyr, were more marked in the severely Mg-restricted group. Femoral Ca and P concentrations were unaffected by dietary Mg restriction. These results show that not only severe but also moderate dietary restriction of Mg over 21 d results in qualitative changes in bone (i.e. reduced Mg concentration) as well as in aberrant bone turnover in young growing rats (i.e. severely depressed rates of bone formation and bone resorption), which may impair bone development and bone strength.

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Alfacalcidol prevents aromatase inhibitor (Letrozole)-induced bone mineral loss in young growing female rats

Journal of Endocrinology ◽

10.1677/joe-08-0532 ◽

2009 ◽

Vol 202 (2) ◽

pp. 317-325 ◽

Cited By ~ 3

Author(s):

Idris Mohamed ◽

James K Yeh

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Bone Formation ◽

Bone Mass ◽

Oral Administration ◽

Aromatase Inhibitor ◽

Bone Mineral ◽

Female Rats ◽

Bone Area ◽

Combined Intervention

Long-term aromatase inhibitor use causes bone loss and increases fracture risk secondary to induced estrogen deficiency. We postulated that alfacalcidol (A; vitamin D3 analog) could help prevent the Letrozole (L)-induced mineral bone loss. Fifty intact 1-month-old female rats were randomly divided into basal group; age-matched control group (AMC); L group: oral administration of 2 mg/kg per day; A group: oral administration of 0.1 μg/kg per day; and group L+A for a period of 8 weeks. Eight-week administration of L resulted in a significant increase in body weight, bone length, bone area, bone formation, and bone resorption activities when compared with the AMC group. However, the bone mass and bone mineral density (BMD) were significantly lower than the AMC group. Serum levels of testosterone, LH, FSH, and IGF-1 were significantly higher and serum estrone and estradiol were lower along with a decrease in ovary+uterus horn weight, when compared with the AMC groups. None of those parameters were affected by A treatment, except suppression of bone resorption activities and increased trabecular bone mass and femoral BMD, when compared with the AMC group. Results of L+A combined intervention showed that bone length, bone area, and bone formation activities were higher than the AMC group, and the bone resorption activities were lower and BMD was significantly higher than that of the L group. This study demonstrates that the combined intervention of L and A not only enhances bone growth, but also increases bone density, and the effects of L and A are independent and additive.

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Bone mechanical properties after exercise training in young and old rats

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.1.130 ◽

1990 ◽

Vol 68 (1) ◽

pp. 130-134 ◽

Cited By ~ 110

Author(s):

D. M. Raab ◽

E. L. Smith ◽

T. D. Crenshaw ◽

D. P. Thomas

Keyword(s):

Mechanical Properties ◽

Dry Weight ◽

Ultimate Stress ◽

Moment Of Inertia ◽

Female Rats ◽

Stress And Strain ◽

Nonsignificant Trend ◽

Fischer 344 ◽

Old Rats ◽

Both Bones

The effects of a 10-wk training regimen on the mechanical properties of the femur and humerus were evaluated in 2.5- and 25-mo-old Fischer 344 female rats. The rats trained on a rodent treadmill 5 days/wk for 10 wk. Duration, grade, and speed increased until the rats maintained 1 h/day at 15% grade and either 15 m/min (old rats) or 36 m/min (young rats). Excised bones were mechanically tested with a 3-point flexure test for mechanical properties of force, stress, and strain. Fat-free dry weight (FFW) and moment of inertia were also obtained. With aging, similar increases were observed in both the femur and humerus for FFW, moment of inertia, and force. Ultimate stress was reduced in the senescent femur while strain was elevated; a similar but nonsignificant trend was observed in the humerus. Irrespective of age, training increased FFW in the femur and, to a lesser degree, in the humerus. Breaking force was elevated for both bones after training. In young and old bones, the training-induced differences in bone mass and force were similar, despite differences in training intensity. In the old trained rats, femur ultimate stress was greater than that in control rat femurs and similar to that in young rat femurs. The results of the present study indicate that training effects were not limited by age.

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Studies of acute effect of prolactin on distribution of absorbed calcium and long-term effect on calcium balance in weaned, young, and sexually mature rats

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y94-218 ◽

1994 ◽

Vol 72 (12) ◽

pp. 1521-1527 ◽

Cited By ~ 4

Author(s):

N. Krishnamra ◽

V. Cheeveewattana

Keyword(s):

Body Weight ◽

Bone Resorption ◽

Bone Formation ◽

Calcium Content ◽

Dry Weight ◽

Acute Effect ◽

Female Rats ◽

Daily Injection ◽

Calcium Excretion ◽

Calcium Balance

An acute effect of a single dose of 0.02 mg prolactin/100 g body weight administered intraperitoneally on distribution of absorbed calcium and the effect of daily subcutaneous injections of 0.25 mg prolactin/100 g body weight for 13 days on calcium balance were assessed in weaned, young, and mature female rats. The acute administration of prolactin failed to affect distribution of absorbed calcium at 2 h after instillation of test solution. In contrast, the daily injection of a lower dose of prolactin over 13 days significantly decreased fecal and urinary excretion of 45Ca, an index of absorbed calcium, in mature rats, while having no effect on muscle and tibial 45Ca contents. In young rats, in addition to a reduction in the urinary 45Ca excretion, prolactin decreased the gastrocnemius muscle total calcium content from 7.28 ± 0.37 to 5.58 ± 0.37 μmol/g dry weight (p < 0.01) while increasing tibial calcium content from 6.65 ± 0.18 to 7.35 ± 0.15 mmol/g dry weight (p < 0.01). Bone formation (represented by serum alkaline phosphatase) in weaned rats was significantly elevated by prolactin, but bone resorption (represented by urinary hydroxyproline) was not altered. It could be concluded that prolonged administration of prolactin decreased calcium excretion in mature rats and increased bone formation and tibial calcium content in growing rats.Key words: bone formation, bone resorption, calcium, calcium balance, prolactin.

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Impaired Estrogen Sensitivity in Bone by Inhibiting Both Estrogen Receptor a and b Pathways*

10.31234/osf.io/592mt ◽

2020 ◽

Author(s):

Lungwani Muungo

Keyword(s):

Bone Mineral Density ◽

Estrogen Receptor ◽

Bone Loss ◽

Bone Turnover ◽

Bone Mineral ◽

Female Rats ◽

Wild Type ◽

Mineral Density ◽

Transgenic Rats ◽

Estrogen Sensitivity

Although it is well established that estrogen deficiencycauses osteoporosis among the postmenopausalwomen, the involvement of estrogen receptor (ER) in itspathogenesis still remains uncertain. In the presentstudy, we have generated rats harboring a dominantnegative ERa, which inhibits the actions of not only ERabut also recently identified ERb. Contrary to our expectation,the bone mineral density (BMD) of the resultingtransgenic female rats was maintained at the same levelwith that of the wild-type littermates when sham-operated.In addition, ovariectomy-induced bone loss wasobserved almost equally in both groups. Strikingly, however,the BMD of the transgenic female rats, after ovariectomized,remained decreased even if 17b-estradiol(E2) was administrated, whereas, in contrast, the decreaseof littermate BMD was completely prevented byE2. Moreover, bone histomorphometrical analysis ofovariectomized transgenic rats revealed that the higherrates of bone turnover still remained after treatmentwith E2. These results demonstrate that the preventionfrom the ovariectomy-induced bone loss by estrogen ismediated by ER pathways and that the maintenanceof BMD before ovariectomy might be compensatedby other mechanisms distinct from ERa and ERbpathways.

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Treatment with Cinacalcet in Hemodialysis Patients with Severe Secondary Hyperparathyroidism, Influences Bone Mineral Metabolism and Anemia Parameters

Current Drug Therapy ◽

10.2174/1574885514666190802144629 ◽

2020 ◽

Vol 15 (3) ◽

pp. 249-263

Author(s):

Maria Aktsiali ◽

Theodora Papachrysanthou ◽

Ioannis Griveas ◽

Christos Andriopoulos ◽

Panagiotis Sitaras ◽

...

Keyword(s):

Bone Mineral ◽

Mineral Metabolism ◽

Treatment Options ◽

Dry Weight ◽

Chronic Hemodialysis ◽

Protective Agent ◽

Positive Correlation ◽

Stage Renal Disease ◽

End Stage ◽

Esrd Patients

Background: Due to the premium rate of Chronic Kidney Disease, we have increased our knowledge with respect to diagnosis and treatment of Bone Mineral Disease (BMD) in End- Stage Renal Disease (ESRD). Currently, various treatment options are available. The medication used for Secondary Hyper-Parathyroidism gives promising results in the regulation of Ca, P and Parathormone levels, improving the quality of life. The aim of the present study was to investigate the relation of cinacalcet administration to not only parathormone, Ca and P but also to anemia parameters such as hematocrit and hemoglobin. Materials and Methods: retrospective observational study was conducted in a Chronic Hemodialysis Unit. One-hundred ESRD patients were recruited for twenty-four months and were evaluated on a monthly rate. Biochemical parameters were related to medication prescribed and the prognostic value was estimated. Cinacalcet was administered to 43 out of 100 patients in a dose of 30-120 mg. Results: Significant differences were observed in PTH, Ca and P levels with respect to Cinacalcet administration. Ca levels appeared to be higher at 30mg as compared to 60mg cinacalcet. Furthermore, a decreasing age-dependent pattern was observed with respect to cinacalcet dosage. A positive correlation was observed between Dry Weight (DW) and cinacalcet dose. Finally, a positive correlation between Hematocrit and Hemoglobin and cinacalcet was manifested. Conclusions: Cinacalcet, is a potential cardiovascular and bone protective agent, which is approved for use in ESRD patients to assist SHPT. A novel information was obtained from this study, regarding the improvement of the control of anemia.

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Evidence for bone mineral density and bone resorption in middle and elderly women with knee osteoarthritis in Shanghai: a cross sectional study

Osteoarthritis and Cartilage ◽

10.1016/j.joca.2018.02.514 ◽

2018 ◽

Vol 26 ◽

pp. S250-S251

Author(s):

Q. Xiaofeng

Keyword(s):

Bone Mineral Density ◽

Bone Resorption ◽

Knee Osteoarthritis ◽

Bone Mineral ◽

Elderly Women ◽

Cross Sectional Study ◽

Sectional Study ◽

Mineral Density ◽

Cross Sectional

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The effect of prolactin itself and in combination with estrogen on bone mineral density in female rats

Gynecological Endocrinology ◽

10.1080/09513590.2018.1548592 ◽

2019 ◽

Vol 35 (6) ◽

pp. 539-543 ◽

Cited By ~ 1

Author(s):

Forough Saki ◽

Faezeh Sadeghian ◽

Seyed Reza Kasaee ◽

Pedram Talezadeh ◽

Gholam Hossein Ranjbar Omrani

Keyword(s):

Bone Mineral Density ◽

Bone Mineral ◽

Female Rats ◽

Mineral Density

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Effects of trenbolone acetate and testosterone on growth and on plasma concentrations of corticosterone and ACTH in rats

Journal of Endocrinology ◽

10.1677/joe.0.1260461 ◽

1990 ◽

Vol 126 (3) ◽

pp. 461-466 ◽

Cited By ~ 8

Author(s):

M. N. Sillence ◽

R. G. Rodway

Keyword(s):

Weight Gain ◽

Growth Response ◽

Plasma Concentrations ◽

Female Rats ◽

Male Rats ◽

Adrenal Weight ◽

Trenbolone Acetate ◽

Male And Female Rats ◽

Age Related ◽

Old Rats

ABSTRACT The effects of trenbolone acetate (TBA) on growth and on plasma concentrations of corticosterone were examined in male and female rats. At 5 weeks of age, rats were injected with TBA (0·8 mg/kg) dissolved in peanut oil, or with oil alone, daily for 10 days. In female rats, TBA caused an increase in weight gain (20–38%), a reduction in adrenal weight (19%) and a reduction in plasma concentrations of corticosterone (55%). In contrast, TBA-treated male rats showed no significant increase in weight gain, no significant change in adrenal weight and no reduction in plasma concentrations of corticosterone. The mechanism by which adrenal activity was suppressed in TBA-treated female rats was examined and the response compared with that to testosterone. Female rats (8 weeks old) were injected daily either with oil vehicle, TBA (0·8 mg/kg) or testosterone propionate (0·8 mg/kg). Testosterone increased weight gain (24%), but the growth response to TBA treatment was significantly greater (97%). A reduction in plasma concentrations of corticosterone (45%) was again observed in response to TBA. However, testosterone increased plasma concentrations of corticosterone (52%) above those of control values. Neither androgen affected plasma concentrations of ACTH. Finally, the effects of TBA were examined in 6-week-old female rats, to characterize further the apparent age-related increase in responsiveness. The growth response of 6-week-old rats (60–74%) was intermediate between that seen in 5- and 8-week-old animals. It is concluded that part of the anabolic activity of TBA may be related to a reduction in circulating concentrations of corticosterone. The effect of TBA on corticosterone concentrations differs from that of the natural androgen, testosterone, and does not appear to be mediated by a reduction in plasma concentrations of ACTH. Journal of Endocrinology (1990) 126, 461–466

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