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

1994 ◽  
Vol 72 (12) ◽  
pp. 1521-1527 ◽  
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.

Effects of exercise and immobilization on bone formation and resorption in young rats

1993 ◽  
Vol 264 (2) ◽  
pp. E182-E189 ◽  
Author(s):  
J. K. Yeh ◽  
C. C. Liu ◽  
J. F. Aloia
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Formation Rate ◽  
Calcium Content ◽  
Experimental Period ◽  
Female Rats ◽  
Control Group ◽  
Initial Increase ◽  
Bone Formation Rate ◽  
Tetracycline Labeling

The influence of physical activity on bone formation and resorption was studied in the following three groups of 6-wk-old female rats: 30 controls, 24 sciatic denervation immobilized, and 28 treadmill exercised. Bone formation and resorption were determined from 45Ca retention, 45Ca excretion, bone calcium content, bone volume, and resorbing surface and bone formation rate assessed by tetracycline labeling. 45Ca (30 microCi) was administered intravenously to each animal before study, and the excretion of isotope in the urine and feces was then determined during the 6-wk experimental period. Exercise resulted in an initial increase in total excretion of 45Ca (P < 0.01) followed by a drop to below control levels (P < 0.001). The femoral 45Ca retention and calcium content of the exercised group were higher than that of the control group at week 6. Periosteal bone formation rate in the tibia was enhanced during days 32–41 (P < 0.01). With immobilization, the weekly excretion of 45Ca was persistently higher (P < 0.01), and the femoral 45Ca retention (P < 0.05) and calcium content (P < 0.01) were lower than the control group. Periosteal and endosteal bone formation rates were lower than in the controls over the first 31 days. In conclusion, exercise in young growing rats is associated with an initial increase and then a decrease in bone resorption while active bone formation is sustained. Immobilization for 6 wk results in an increase in bone resorption and a rapid fall in bone formation.

Rates of New Bone Formation in Patients with Crush Fracture Osteoporosis

1982 ◽  
Vol 63 (2) ◽  
pp. 153-160 ◽  
Author(s):  
J. Reeve ◽  
J. R. Green ◽  
R. Hesp ◽  
Patricia Hulme
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Accretion Rate ◽  
Positive Association ◽  
Calcium Balance ◽  
Tracer Technique ◽  
New Bone Formation ◽  
True Rate ◽  
Exchange Processes

1. Calcium balances and formation rates of new bone measured with an improved tracer technique using 85Sr have been determined simultaneously in 21 patients with idiopathic osteoporosis and vertebral crush fractures. 2. A weak positive association was found between calcium balance and the kinetically measured calcium accretion rate, which is the sum of the true rate of bone formation and various long-term exchange processes. 3. The more negative balances were associated with significantly greater early loss of tracer taken up into bone by ‘accretion’, so that long-term (> 200 day) uptake was reduced. 4. This indicates that patients actively losing bone mineral have lower true rates of bone formation and higher rates of long-term exchange than their fellow patients who are more nearly in calcium equilibrium. 5. No statistically significant association was found between measured rates of bone resorption and calcium balance.

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

1999 ◽  
Vol 82 (1) ◽  
pp. 63-71 ◽  
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.

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

2001 ◽  
Vol 86 (4) ◽  
pp. 453-459 ◽  
Author(s):  
Annette Creedon ◽  
Kevin D. Cashman
Keyword(s):  
Bone Resorption ◽  
Bone Mineral ◽  
Dry Weight ◽  
Female Rats ◽  
Wistar Strain ◽  
Restricted Group ◽  
Growing Rat ◽  
Old Rats ◽  
Bone Mineral Accrual ◽  
Recommended Level

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.

Variation in the size and position of Hymenolepis diminuta (Cestoda: Cyclophyllidea) within the rat intestine

1969 ◽  
Vol 47 (6) ◽  
pp. 1091-1101 ◽  
Author(s):  
D. F. Mettrick ◽  
Lorna C. Dunkley
Keyword(s):  
Body Weight ◽  
Experimental Design ◽  
Frequency Distribution ◽  
Dry Weight ◽  
Pyloric Sphincter ◽  
Hymenolepis Diminuta ◽  
Female Rats ◽  
Rat Intestine ◽  
Male And Female ◽  
Male And Female Rats

Data on the dry weight of 410 worms from both male and female rats is shown not to differ significantly from the normal (Gaussian) frequency distribution. This finding justified the use of statistics based on this function.Host body weight is shown to have a highly significant (P < 0.01) effect upon worm dry weight. The heavier the rat, the smaller the worms. An experimental design taking rat body weight into consideration is shown to be up to 36% more efficient in demonstrating differences between groups than one that ignores this source of variation. The point of scolex attachment behind the pyloric sphincter also has a significant effect (P < 0.05) upon worm dry weight. The nearer the scolex is to the stomach, the smaller the worm.The distribution of worm biomass in the intestine does not follow a normal (Gaussian) frequency, but is both asymmetrical (P < 0.001) and flattened (P < 0.001). Over 50% of the parasite biomass lies within the second quarter of the intestine. The distribution of the median points of worm strobilae in the rat intestine is also asymmetrical (P < 0.01) with a peak in the zone which represents a distance of 30–35% from the stomach.The migration of H. diminuta within the rat intestine results in the greater part of the parasite body lying in the second quarter of the intestine. The median points of the strobilae are concentrated at the junction of the first and second quarters of the intestine. This region of the rat intestine appears to offer the optimum site for the growth of H. diminuta.

Iron deficiency and high-intensity running interval training do not impact femoral or tibial bone in young female rats

2021 ◽  
pp. 1-22
Author(s):  
Jonathan M. Scott ◽  
Elizabeth A. Swallow ◽  
Corinne E. Metzger ◽  
Rachel Kohler ◽  
Joseph M. Wallace ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Resorption ◽  
Iron Deficiency ◽  
Bone Formation ◽  
High Intensity ◽  
Female Rats ◽  
Type I ◽  
Bone Resorption Markers ◽  
Iron Deficient ◽  
Tracp 5B

Abstract In the US, as many as 20% of recruits sustain stress fractures during basic training. In addition, approximately one-third of female recruits develop iron deficiency upon completion of training. Iron is a cofactor in bone collagen formation and vitamin D activation, thus we hypothesized iron deficiency may be contributing to altered bone microarchitecture and mechanics during 12-weeks of increased mechanical loading. Three-week old female Sprague Dawley rats were assigned to one of four groups: iron adequate sedentary, iron deficient sedentary, iron adequate exercise, and iron deficient exercise. Exercise consisted of high-intensity treadmill running (54 min 3×/week). After 12-weeks, serum bone turnover markers, femoral geometry and microarchitecture, mechanical properties and fracture toughness, and tibiae mineral composition and morphometry were measured. Iron deficiency increased the bone resorption markers C-terminal telopeptide type I collagen and tartate-resistant acid phosphatase 5b (TRAcP 5b). In exercised rats, iron deficiency further increased bone TRAcP 5b, while in iron adequate rats, exercise increased the bone formation marker procollagen type I N-terminal propeptide. In the femur, exercise increased cortical thickness and maximum load. In the tibia, iron deficiency increased the rate of bone formation, mineral apposition, and zinc content. These data show that the femur and tibia structure and mechanical properties are not negatively impacted by iron deficiency despite a decrease in tibiae iron content and increase in serum bone resorption markers during 12-weeks of high-intensity running in young growing female rats.

scholarly journals Effects of the Circadian Variation in Serum Cortisol on Markers of Bone Turnover and Calcium Homeostasis in Normal Postmenopausal Women1

1998 ◽  
Vol 83 (3) ◽  
pp. 751-756 ◽  
Author(s):  
Hassan M. Heshmati ◽  
B. Lawrence Riggs ◽  
Mary F. Burritt ◽  
Carol A. McAlister ◽  
Peter C. Wollan ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Bone Turnover ◽  
Type I Collagen ◽  
Serum Cortisol ◽  
Urinary Calcium ◽  
Calcium Excretion ◽  
Type I ◽  
Serum Osteocalcin ◽  
Circadian Pattern

Bone turnover has a circadian pattern, with bone resorption and, to a lesser extent, bone formation increasing at night. Serum cortisol also has a circadian pattern and is a potential candidate for mediating the circadian changes in bone turnover. Thus, we measured bone formation and resorption markers before (study A) and after (study B) elimination of the morning peak of cortisol. We also assessed effects of the circadian cortisol pattern on serum calcium, PTH, and urinary calcium excretion. Ten normal postmenopausal women, aged 63–75 yr (mean, 69 yr), were studied. Metyrapone was administered to block endogenous cortisol synthesis and either a variable (study A) or a constant (study B) infusion of cortisol was given to reproduce and then abolish the morning cortisol peak. Blood was sampled every 2 h for serum cortisol, ionized calcium, PTH, and bone formation markers[ osteocalcin and carboxyl-terminal propeptide of type I collagen (PICP)], and timed 4-h urine samples were collected for measurement of calcium, phosphorus, sodium, potassium, and bone resorption markers (N-telopeptide of type I collagen and free deoxypyridinoline). During study A, serum osteocalcin had a circadian pattern, with a peak at 0400 h and a nadir at 1400 h. During study B, however, the afternoon nadir of serum osteocalcin was eliminated (P &lt; 0.001 and P &lt; 0.005 for the difference in the patterns of peak and nadir, respectively, on the 2 study days). In contrast, the circadian patterns of serum PICP and urinary N-telopeptide of type I collagen and free deoxypyridinoline were virtually identical during the two studies. Urinary calcium excretion declined after the cortisol peak, without differences between the 2 study days in phosphorus or sodium excretion or in serum PTH. We conclude that the circadian variation in serum cortisol is responsible for the circadian pattern of serum osteocalcin, but not that of PICP or bone resorption markers. The physiological variation in serum cortisol may also reduce urinary calcium excretion.

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

2009 ◽  
Vol 202 (2) ◽  
pp. 317-325 ◽  
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.

Modulation of the Anabolic Effect of Synthetic Human Parathyroid Hormone Fragment-(1-34) in the Bone of Growing Rats by Variations in the Dosage Regimen

1993 ◽  
Vol 85 (2) ◽  
pp. 223-228 ◽  
Author(s):  
Jean-Luc Riond
Keyword(s):  
Body Weight ◽  
Parathyroid Hormone ◽  
Calcium Absorption ◽  
Dry Weight ◽  
Vehicle Control ◽  
Intestinal Calcium Absorption ◽  
Calcium Balance ◽  
Anabolic Effect ◽  
Dihydroxyvitamin D3 ◽  
Female Wistar Rats

1. The influence of the time of the day of the administration of synthetic human parathyroid hormone fragment-(1-34) [hPTH-(1-34)] on its anabolic effect in bone was investigated in 23 60-day-old female Wistar rats. Rats were randomly assigned to the groups vehicle control morning, hPTH-(1-34)-treated morning, vehicle control afternoon and hPTH-(1-34)-treated afternoon, and once daily received a subcutaneous injection of 8 μg of hPTH-(1-34)/100 g body weight for 11 days. The increase in net intestinal calcium absorption and the increase in calcium balance were not influenced by the time of day of hPTH-(1-34) treatment. Four days after cessation of treatment, the net intestinal calcium absorption and calcium balance in hPTH-(1-34)-treated rats were not different from those of the control rats. 2. Modulation of the anabolic effect by variation of the hPTH-(1-34) dosage regimen was investigated in 43 60-day-old female Wistar rats. Rats were randomly assigned to the groups vehicle control, environmental control, 8 μg of hPTH-(1-34)/100 g body weight every 3 days for 24 days, 8 μg of hPTH-(1-34)/100g body weight every 2 days for 16 days, 8 μg of hPTH-(1-34)/100 g body weight every day for 8 days, 4 μg of hPTH-(1-34)/100 g body weight twice a day for 8 days and 2.7 μg of hPTH-(1-34)/100 g body weight three times a day for 8 days. In all cases, the total dose of hPTH-(1-34) received was 64 μg/100g body weight. Net intestinal calcium absorption and calcium balance increased significantly in the groups that received hPTH-(1-34) once a day, twice a day and three times a day. In relation with increased frequency of dosing, a significant linear trend existed for the increase in net intestinal calcium absorption and calcium balance. The hPTH-(1-34)-induced increase in total tibia calcium, total vertebrae calcium, tibia dry weight and vertebrae dry weight also tended to be more pronounced with more frequent dosing, although the trend was not significant. 3. Thus, smaller intervals between doses of hPTH-(1-34) enhance the anabolic response in bone despite the smaller doses. This effect may be secondary to 1,25-dihydroxyvitamin D3-induced increased intestinal calcium absorption, decreased 1,25-dihydroxyvitamin D3-induced bone resorption, up-regularion of osteoblast receptors for parathyroid hormone, or a combination of these three factors.

Sign in / Sign up

Export Citation Format

Share Document