Raloxifene similarly affects the skeletal system of male and ovariectomized female rats

Raloxifene, a selective estrogen receptor modulator, is used for prevention and treatment of osteoporosis in postmenopausal women. Raloxifene use in male subjects is increasingly considered and a few clinical studies of its effect on bone turnover have already been performed. The aim of the present study was to investigate the effects of raloxifene on the skeletal system of healthy mature male rats. The experiments were performed on mature male Wistar rats, treated daily with raloxifene hydrochloride at a dose of 5 mg/kg po for 4 weeks. Bone mass, mineral content, macrometric and histomorphometric parameters, as well as mechanical properties were examined. For comparison, we also studied the effects of raloxifene on the skeletal system of mature ovariectomized female rats. Raloxifene administration to male rats caused statistically significant increases in the bone mass/body mass ratio, bone mineral content/body mass ratio and bone mineral content/bone mass ratio in comparison with those of the control rats. Bone mechanical properties and most of histomorphometric parameters remained unchanged. Also in ovariectomized female rats, raloxifene administration caused statistically significant increases in the bone mass/body mass ratio, bone mineral content/body mass ratio and bone mineral content/bone mass ratio in comparison with the results obtained in the ovariectomized control rats, to the level of sham-operated control rats. Moreover, raloxifene counteracted the development of changes in histomorphometric parameters caused by ovariectomy in female rats, but did not significantly affect bone mechanical properties. In conclusion, the changes induced by raloxifene in the skeletal system of male rats were similar to those induced by the drug in ovariectomized female rats.     

Effect of administration of alendronate sodium and retinol on the mechanical properties of the femur in ovariectomized rats

Alendronate sodium, an aminobisphosphonate with potent antiresorptive activity, is used in the treatment of postmenopausal osteoporosis. Retinol, as a component of multivitamin preparations, is frequently used especially by elderly people. There are no reports on the interaction of alendronate sodium and retinol. The aim of the present study was to investigate the effect of administration of alendronate sodium and retinol on mechanical properties of the femoral bone in bilaterally ovariectomized rats. The experiments were carried out on 3-month-old Wistar rats, divided into 7 groups: I - sham-operated control rats, II - ovariectomized control rats, III - ovariectomy + alendronate sodium 3 mg/kg po, IV - ovariectomy + retinol 700 IU/kg po, V - ovariectomy + retinol 3500 IU/kg po, VI - ovariectomy + alendronate sodium 3 mg/kg po + retinol 700 IU/kg po, VII - ovariectomy + alendronate sodium 3 mg/kg po + retinol 3500 IU/kg po. The drugs were administered to the rats daily by oral gavage for 28 days. Body mass gain, bone mass, bone mineral content and calcium content in the femur and L-4 vertebra and mechanical properties of the whole femur (extrinsic stiffness, ultimate load, breaking load, deformation caused by the ultimate load) and the neck of the femur (load at fracture), were examined. Bilateral ovariectomy induced osteopenic changes in the rat skeletal system. Alendronate sodium (3 mg/kg po) counteracted the development of osteopenia induced by ovariectomy. Retinol at both used doses unfavorably affected the examined bone parameters of ovariectomized rats. Retinol administered with alendronate sodium lessened the preventive action of alendronate on the development of osteopenic changes in the skeletal system of ovariectomized rats.     

Do effects of propranolol on the skeletal system depend on the estrogen status?

BackgroundPropranolol, a nonselective β-adrenergic receptor antagonist, was reported to favorably affect the skeletal system in different animal models. The aim of the study was to investigate whether the effects of propranolol on the skeletal system depend on the estrogen status.MethodsThe in vivo experiments were carried out on the following groups of mature female Wistar rats: sham-operated control rats, sham-operated rats receiving propranolol, ovariectomized (OVX) control rats, OVX rats receiving propranolol, OVX rats receiving estradiol, OVX rats receiving estradiol and propranolol. Propranolol hydrochloride (10 mg/kg po) and/or estradiol (0.1 mg/kg po) were administered daily for 4 weeks. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. In vitro, effects of estradiol and propranolol on the formation of mouse osteoclasts and on the mRNAexpression of genes related to osteoclastogenesis, bone formation and mineralization, as well as adrenergic and estrogen signalling in mouse osteoblasts were investigated.Results and conclusionPropranolol exerted some favorable effects on the rat skeletal system in vivo, independently of the estrogen status. However, in vitro studies indicated a possibility of some antagonistic relations between the estradiol and propranolol effects.     

Effects of alpha-Escin on mechanical features of the femoral bone in rats with experimental post-steroid osteopenia

The aim of the present study was to investigate the effects of alpha-escin on the experimental prednisolone-induced osteopenia. The experiments were carried out on male Wistar rats of initial body mass 240-310 g, divided into 4 groups (n = 6): I (C)-control, II (E)-alpha-Escin, III (P)-Prednisolone, IV (E + P)-Prednisolone + alpha-escin. Prednisolone (5 mg/kg i.m. daily) and/or alpha-escin (100 mg/kg p.o. daily) were administered for 28 days. Studies into the effect of alpha-escin on the development of steroid-induced osteopenia included the determination of an increase in body and adrenal glands mass in rats, determination of macrometrical parameters, of calcium and other minerals density in examined bones and determination of mechanical endurance of femoral bone. The carried-out experiments indicated that the p.o. administration of 100 mg/kg of alpha-escin for 28 days to sexually mature male rats with experimental steroid-induced osteopenia caused slight protective action on bone tissue against unfavourable influence of prednisolone manifested by enhancement of mechanical features of femoral bone.     

Effects of catecholamines on the intramedullary pressure in the femur in rats with prednisolone-induced osteoporosis

Osteoporosis is a metabolic bone disease characterized by low bone mass, impaired micro-architecture and susceptibility to fracture. Osteoporosis may be, inter alia, a result of a long-term glucocorticosteroid therapy, e.g. with prednisolone. Although a number of properties of prednisolone in influencing bone metabolism have been recognized, the effect of prednisolone-induced osteoporosis on the function of blood circulation and autonomic nervous system in bones remains open. In order to clarify this problem, the present study concentrated on the effects of catecholamines on intramedullary pressure in rats with prednisolone-induced osteoporosis. Prednisolone was administered to male Wistar rats at the doses of 5 mg/kg im, for 3 weeks. Norepinephrine, epinephrine, isoprenaline as well as adrenoceptor antagonists (phentolamine and propranolol) were administered to the controls and to the rats with prednisolone-induced osteoporosis. The examinations demonstrated that rats with prednisolone-induced osteoporosis displayed a decreased intramedullary pressure. In addition, a disordered effect of catecholamines on intramedullary pressure of osteoporotic bone was observed.     

Proton pump (H+/K+-ATPase) inhibitors weaken the protective effect of alendronate on bone mechanical properties in estrogen-deficient rats

BackgroundAlendronate can induce esophagitis and stomach ulceration requiring the concurrent use of drugs which decrease HCl production. The aim of the present study was to investigate the effect of concurrent administration of proton pump inhibitors, omeprazole or pantoprazole, and alendronate on the mechanical properties of long bones in bilaterally ovariectomized (OVX) rats.MethodsThe experiments were carried out on 3-month-old Wistar rats, divided into following groups: non-ovariectomized control rats, OVX control rats, OVX rats administered omeprazole or pantoprazole, OVX rats administered alendronate, OVX rats administered alendronate and omeprazole or pantoprazole. The drugs were administered to the rats for 28 days: alendronate at a dose of 3 mg/kg po, omeprazole or pantoprazole at a dose of 3 mg/kg ip. Mechanical properties of tibial metaphysis, femoral diaphysis and femoral neck were assessed. Bone macrometric parameters, mass and mass of bone mineral were also examined in the tibia and femur.ResultsEstrogen deficiency caused development of osteopenia with significant worsening of bone mechanical properties. Alendronate counteracted the deleterious changes in bone mechanical properties of the tibial metaphysis and femoral neck induced by estrogen deficiency. Pantoprazole worsened mechanical properties of the tibia in estrogen-deficient rats. Omeprazole or pantoprazole administered concurrently with alendronate attenuated the effect of alendronate on mechanical properties of the tibial metaphysis and femoral neck in ovariectomized rats. The unfavorable effect of pantoprazole was stronger than that of omeprazole.ConclusionProton pump inhibitors weakened the protective effect of alendronate on bone mechanical properties in estrogendeficient rats.     

Effects of vigabatrin on the skeletal system of young rats

Long-term administration of antiepileptic drugs may be connected with the risk of impairment of bone remodeling. Contrary to the reported unfavorable effect of classic antiepileptic drugs on bone metabolism, little is known about the effect of the next generation antiepileptics on bone remodeling. The aim of the present study was to investigate the effect of vigabatrin, as a representative of new antiepileptics, on the skeletal system of young rats, in comparison with conventional drugs--phenytoin and valproic acid. The experiments were carried out on 4-week-old male Wistar rats, divided into the control rats, and rats receiving vigabatrin (250 mg/kg p.o. daily), phenytoin (20 mg/kg p.o. daily) or valproic acid (250 mg/kg p.o. daily). The drugs were administered for 28 days. Histomorphometric parameters of the tibia and femur, mechanical properties of the femur, and bone length, diameter, mass, content of mineral substances and calcium were examined. After administration of phenytoin or valproic acid, the investigated bone parameters did not significantly differ from those observed in the control rats. Administration of vigabatrin caused profound impairment of bone accrual with impairment of bone histomorphometric parameters, along with the significant decrease in the body mass gain.     

In vivo effects of high-dose methotrexate on bone remodeling in rats

Methotrexatae (MTX) is a folate antagonist. MTX osteopathy is well recognized to accompany a high-dose therapy with this drug for the treatment of childhood malignancy. Clinical tests also show that low-dose MTX used in the treatment of rheumatoid arthritis may impair bone formation in a population already predisposed to osteoporosis. However, results of clinical tests are hard to interpret, as it is necessary to take into account malignancy-induced changes in the osseous tissue, long-term immobility and concurrent administration of glucocorticosteroids. We conducted in vivo tests to evaluate the effects of oral and intramuscular administration of high dose of MTX on bone remodeling processes in rats. Effects of MTX on the processes of bone remodeling were evaluated by assessing macrometric and histomorphometric parameters as well as mechanical properties of the femur. The tests were carried out on male Wistar rats. Animals were divided into four groups, composed of 7 animals each: Control group (0.9% NaCl solution), MTX-1 po group (MTX at the dose of 1 mg/kg po daily for 10 days: every day for the first five days, and after an 18-day interval, every day for five days), MTX-1 im group (MTX at the dose of 1 mg/kg im daily for 10 days: every day for the first five days, and after an 18-day interval, every day for five days), MTX-5 im group (MTX at the dose 5 mg/kg im daily for 2 days a week for the period of four weeks). Changes in bone remodeling were examined 4 weeks after the first MTX administration. These results show that MTX administered intramuscularly at high doses inhibited the formation and mineralization of new osseous matrix and impaired mechanical properties of the femoral bone, whereas its oral administration had no effect on bone remodeling in rats.     

Prophylactic Effects of Propranolol versus the Standard Therapy on a New Model of Disuse Osteoporosis in Rats

Disuse by bed rest, limb immobilization, or space flight causes rapid bone loss by arresting bone formation and accelerating bone resorption. Propranolol (a non-selective β-adrenergic antagonist) has been shown to improve bone properties by increasing bone formation and decreasing bone resorption in an ovariectomy-induced rat model. However, no studies have yet compared the osteoprotective properties of propranolol with well-accepted therapeutic interventions for the treatment and prevention of immobilization/disuse osteoporosis. To clarify this, we investigated the effects of propranolol compared with zoledronic acid and alfacalcidol in a new animal model of immobilization/disuse osteoporosis. Three-month-old male Wistar rats were divided into five groups with six animals in each group: (1) immobilized (IMM) control; (2) normal control; (3) IMM + zoledronic acid (50 μg/kg, intravenous single dose); (4) IMM + alfacalcidol (0.5 μg/kg, per oral daily); (5) IMM + propranolol (0.1 mg/kg, subcutaneously 5 days/week) for 10 weeks. In groups 1 and 3–5, the right hindlimb was immobilized. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and cortical microarchitecture. Treatment with propranolol induced greater reductions in the bone porosity of the right femur and improved the mechanical properties of the femoral mid-shaft femur in comparison to the IMM control. Moreover, treatment with propranolol also improved the microarchitecture of cortical bones when compared with the IMM control, as indicated by scanning electron microscopy. The anti-osteoporotic property of propranolol was comparable with zoledronic acid and alfacalcidol. This study shows that the bone resorption induced by immobilization/disuse in rats can be suppressed by treatment with propranolol.     

Effects of raloxifene on development of the methotrexate-induced changes in bone mechanical properties of male rats

Methotrexate, a cytostatic and immunosuppressive drug, has been reported to deteriorate the osseous system. Raloxifene, a selective estrogen receptor modulator, is used in the prevention and treatment of postmenopausal osteoporosis. There is a lack of data on possible ways of preventing the unwanted skeletal effects of prolonged immunosuppressive therapy. The aim of the present study was to investigate the effects of raloxifene on mechanical properties of the femur in male rats administered methotrexate. The experiments were carried out on mature male Wistar rats, which were divided into 6 groups: controls, rats administered raloxifene hydrochloride (5 mg/kg p.o.), rats administered methotrexate (0.5 mg/kg p.o. or i.m.), and rats administered raloxifene hydrochloride (5 mg/kg p.o.) plus methotrexate (0.5 mg/kg p.o. or i.m.). Raloxifene was administered for 28 days and methothrexate was administered for the first 10 days of the experiment. After 28 days of drug administration, mechanical parameters of the whole femur were determined: the extrinsic stiffness, the ultimate load and the breaking load, deformation caused by the ultimate and breaking loads, and the load causing fracture of the femoral neck. Additionally, the mass of isolated femurs and their mineral and calcium content were determined. Intragastrically or intramuscularly administered methotrexate impaired the endurance of the tested bones. Administration of raloxifene alone had no significant effects on the mechanical parameters of the femur. Administration of raloxifene resulted in a reduction of the adverse changes in the osseous system induced by methotrexate. Concluding, the experiments demonstrated a protective action of raloxifene against the effects of methotrexate on the osseous system in male rats.     

Thalidomide affects the skeletal system of ovariectomized rats

Apart from having written an inglorious chapter in the history of medicine, thalidomide is currently being intensely studied because of its multidimensional activity. The aim of this study was to examine the effects of thalidomide on the skeletal system in ovariectomized and non-ovariectomized rats.The experiments were carried out with femaleWistar rats, divided into eight groups: sham-operated control rats; sham-operated rats receiving thalidomide at doses of 15, 30 or 60 mg/kg, po; ovariectomized control rats; ovariectomized rats receiving thalidomide at doses of 15, 30 or 60 mg/kg, po. The drug was administered for 4 weeks.Body mass gain and the mass of the uterus, liver, spleen and thymus were studied. Macrometric parameters and content of mineral substances, calcium and phosphorus in the femur, tibia and L-4 vertebra and histomorphometric parameters of the femur and tibia were examined. In the femur, the mechanical properties of the whole bone and of the femoral neck were examined.Thalidomide did not affect the skeletal system of the non-ovariectomized rats.Bilateral ovariectomy induced osteoporotic skeletal changes in mature female rats. The effects of thalidomide on the skeletal system of ovariectomized rats depended on the dose used. With a dose of 15 mg/kg, po, thalidomide counteracted some osteoporotic changes induced by estrogen deficiency.With a dose of 60 mg/kg, po, thalidomide intensified the destructive effects of estrogen deficiency on the rat skeletal system.     

Effect of concurrent administration of alendronate sodium and retinol on development of changes in histomorphometric parameters of bones induced by ovariectomy in rats

Retinol is a commonly used vitamin, especially by elderly people. Alendronate sodium, an aminobisphosphonate, is a potent antiresorptive drug used in the treatment of osteoporosis in postmenopausal women. Frequently, alendronate sodium and retinol are used concurrently. There are no reports on the interaction between alendronate sodium and retinol. The aim of the present study was to investigate the effect of concurrent administration of alendronate sodium and retinol on bone remodeling in ovariectomized rats. The histomorphometric parameters of long bones were studied. The experiments were carried out on 3-month-old Wistar rats, divided into 7 groups: I (C) - sham operated control rats, II (OVX) - ovariectomized control rats, III (OVX + ALN) - ovariectomized rats + alendronate sodium (3 mg/kg po), IV (OVX + R-1) - ovariectomized rats + retinol (700 IU/kg po), V (OVX + R-2) - ovariectomized rats + retinol (3500 IU/kg po), VI (OVX + ALN + R-1) - ovariectomized rats + alendronate sodium (3 mg/kg po) + retinol (700 IU/kg po), VII (OVX + ALN + R-2) - ovariectomized rats + alendronate sodium (3 mg/kg po) + retinol (3500 IU/kg po). The drugs were administered to the rats daily by oral gavage (alendronate sodium in the morning, retinol in the afternoon) for 28 days. Body mass gain, bone mass, mineral content in the tibia, femur and L-4 vertebra, histomorphometric parameters of the right tibia (width of osteoid, periosteal and endosteal transverse growth, area of the transverse cross section of the bone marrow cavity and the cortical bone) and the right femur (width of epiphyseal and metaphyseal trabeculae, width of epiphyseal cartilage) were studied. Bilateral ovariectomy induced osteopenic skeletal changes in mature female rats. Alendronate sodium administered at a dose of 3 mg/kg po daily inhibited the development of changes induced by ovariectomy in the skeletal system of rats. Retinol, especially administered at the dose of 3500 IU/kg daily, intensified the changes in the osseous system caused by estrogen deficiency in rats. Retinol administered concurrently with alendronate sodium attenuated the antiresorptive effect of alendronate sodium on the skeletal system in ovariectomized rats.     

Influence of alpha-escin on the femoral bone strength in ovariectomized rats

The aim of the present study was to investigate the effect of alpha-escin (35 mg/kg po, daily) administered for 4 weeks on the femoral bone strength in 3-month-old ovariectomized Wistar rats. The experiments were carried out on four groups of animals: I (C)-control sham operated rats, II (OVX)-ovariectomized rats, III (E)-sham operated rats which were administered alpha-escin, IV (OVX+E)-ovariectomized rats which were administered alpha-escin. Bilateral ovariectomy caused osteopenic skeletal changes in mature female rats. alpha-Escin (35 mg/kg po, daily) administered to the ovariectomized rats for 28 days only to little extent decreased the development of osteopenic skeletal changes which were caused by bilateral ovariectomy. alpha-Escin (35 mg/kg po, daily) administered to the sham operated rats for 28 days caused slight changes in the skeletal system, which were characterized by the increase in the bone formation processes.     

Relative potencies of three glucocorticoids to induce hypoplasia of the physis and concomitant biochemical alterations in the rat

Although inhaled glucocorticoids are known to have systemic effects on bone metabolism, there is little comparative information on their relative potencies. The effects of three standard glucocorticoids in causing changes in bone metabolism and growth, therefore, were investigated in relation to other systemic effects in the rat. Given to male Sprague-Dawley rats, 4.5–5.5 weeks old, subcutaneously (s.c.), at doses of 0.3–10?mg/kg daily for 7 days, beclomethasone dipropionate, prednisolone and ciclesonide all dose-dependently inhibited thymus body mass index (BMI) (by 57%, 44% and 76% at 3?mg/kg). Ciclesonide, potently and prednisolone, less effectively, also repressed femoral bone growth (by 41% and 18% at 10?mg/kg), significantly reducing body weight gain (both by 100% at 10?mg/kg), and serum concentrations of acid phosphatase (ACP) and tartarate resistant acid phosphatase (TRACP) (by >30% at 10?mg/kg); both increased serum glucose and triglycerides levels. Serum alkaline phosphatase (ALP) was not affected. Beclomethasone dipropionate had little or no effect on these additional variables. In conclusion, ciclesonide showed pronounced bone growth inhibiting activity after s.c. administration to the rat while other two glucocorticoids showed differences in activity on bone metabolism. However, this model is sufficiently sensitive and specific for testing the effect of glucocorticoids on bone metabolism.     

Modifications of histamine receptor signaling affect bone mechanical properties in rats

Histamine receptors are expressed on bone cells and histamine may be involved in regulation of bone metabolism. The aim of the present study was to investigate the effects of loratadine (an H₁ receptor antagonist), ranitidine (an H₂ receptor antagonist) and betahistine (an H₃ receptor antagonist and H₁ receptor agonist) on bone mechanical properties in rats.Loratadine (5 mg/kg/day, po), ranitidine (50 mg/kg/day, po), or betahistine dihydrochloride (5 mg/kg/day, po), were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized (estrogen-deficient) 3-month-old rats, and their effects were compared with appropriate controls. Serum levels of bone turnover markers, bone mineralization and mechanical properties of the proximal tibial metaphysis, femoral diaphysis and femoral neck were studied.In rats with normal estrogen level, administration of loratadine slightly favorably affected mechanical properties of compact bone, significantly increasing the strength of the femoral neck (p < 0.05), and tending to increase the strength of the femoral diaphysis. Ranitidine did not significantly affect the investigated parameters, and betahistine decreased the strength of the tibial metaphysis (cancellous bone, p < 0.01). There were no significant effects of the drugs on serum bone turnover markers. In estrogen-deficient rats, the drugs did not significantly affect the investigated skeletal parameters.In conclusion, the effects of histamine H₁, H₂ and H₃ receptor antagonists on the skeletal system in rats were differential and dependent on estrogen status.     

Effects of curcumin on the skeletal system in rats

There is increasing interest in the discovery of natural compounds that could favorably affect the skeletal system. Curcumin is a constituent of turmeric, a plant which has been used for centuries as a dietary spice and a traditional Indian medicine. Curcumin has been reported to affect differentiation, activity and the lifespan of osteoblasts and osteoclasts in vitro. The aim of the present study was to investigate the effects of curcumin on the skeletal system of rats in vivo. Curcumin (10 mg/kg, po daily) was administered for four weeks to normal (non-ovariectomized) and bilaterally ovariectomized (estrogen-deficient) three-month-old female Wistar Cmd:(WI)WU rats. Ovariectomy was performed seven days before the start of curcumin administration. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, as well as the mechanical properties of the bone, were examined. Serum total cholesterol and estradiol levels were also determined. In rats with normal estrogen levels, curcumin decreased serum estradiol level and slightly increased cancellous bone formation, along with decreased mineralization. Estrogen deficiency induced osteoporotic changes in the skeletal system of the ovariectomized control rats. In ovariectomized rats, curcumin decreased body mass gain and serum total cholesterol level, slightly improved some bone histomorphometric parameters impaired by estrogen deficiency, but did not improve bone mineralization or mechanical properties. In conclusion, the results of the present in vivo study in rats did not support the hypothesis that curcumin, at doses that are readily achievable through dietary intake, could be useful for the prevention or treatment of osteoporosis.     

Marginal zinc deficiency exacerbates bone lead accumulation and high dietary zinc attenuates lead accumulation at the expense of bone density in growing rats.

Environmental lead exposure is associated with reduced bone growth and quality, which may predispose to osteoporosis. Zinc supplementation may reduce lead accumulation; however, effects on bone development have not been addressed. Our objective was to investigate the effects of marginal zinc (MZ) and supplemental zinc (SZ) intakes on bone lead deposition and skeletal development in lead-exposed rats. In a factorial design, weanling Sprague-Dawley rats were assigned to MZ (8 mg/kg diet); zinc-adequate control (CT; 30 mg/kg); zinc-adequate, diet-restricted (DR; 30 mg/kg); or SZ (300 mg/kg) groups, with and without lead acetate-containing drinking water (200 mg Pb/l) for 3 weeks. Excised femurs were analyzed for bone mineral density (BMD) by dual-energy x-ray absorptiometry, morphometry, and mineral content. MZ had higher femur lead and lower femur zinc concentrations and impaired skeletal growth and mineralization than CT. DR inhibited growth but did not result in higher femur lead concentrations than CT. SZ had higher femur zinc and lower femur lead concentrations than the other treatments. DR and SZ had impaired BMD versus CT and MZ. Lead also retarded skeletal growth and impaired BMD, but an interaction between lead and MZ was only found for femoral knee width, which was lower in MZ exposed to lead. In summary, while MZ deficiency exacerbated bone lead concentration, it generally did not intensify lead toxicity. SZ was protective against bone lead but was detrimental to BMD, suggesting that the optimal level of SZ to reduce lead absorption, while supporting growth and bone development, requires further investigation.     

Effects of doxycycline on the development of bone damage caused by prednisolone in rats

The aim of the present study was to investigate the effects of doxycycline on the development of bone damage caused by prednisolone in rats. The experiments were carried out on male WAG rats (200-260 g), divided into 2 control and 6 experimental groups receiving prednisolone (5 mg/kg im daily) or/and doxycycline (100 mg/kg po daily) for 2 or 4 weeks. The animals were sacrificed on the 15th or 29th day of the experiment and the following characteristics were examined: mass, length, mechanical properties, mineral and calcium content in the tibia and femur, width of endosteal and periosteal osteoid, endosteal and periosteal transverse growth, transverse cross-section area of the diaphysis and of the marrow cavity in the tibia, width of epiphyseal cartilage and width of trabeculae in the femur. Prednisolone caused features of osteopenia (inhibition of bone formation and intensification of bone resorption), which were stronger after 4 weeks of the experiment. Doxycycline administered alone for 2 or 4 weeks intensified the processes of bone formation and resorption. Doxycycline to some degree attenuated the influence of prednisolone on rat bones.     

Effect of pamidronate on the action of catecholamines on blood pressure in the marrow cavity of long bones in rats with prednisolone-induced osteoporosis

Pamidronate is a representative of bisphosphonates, which are effectively used in the treatment of bone diseases. Although a number of properties of pamidronate have been recognized which influence the metabolic process in bones, the issue of the effect of bisphosphonates on the function of blood circulation and autonomic nervous system in osteoporotic bones remains open. In order to clarify this problem, the present study concentrated on the effects of pamidronate on catecholamine action on blood pressure in the marrow cavity in rats with prednisolone-induced osteoporosis. The animals were divided into 3 groups: I - control rats; II - rats which were given prednisolone at the dose of 5 mg/kg, im, for 3 weeks; III - rats which were given prednisolone at the dose of 5 mg/kg, im and pamidronate at the dose of 3 mg/kg, sc together, for 3 weeks. The experiments demonstrated that rats with prednisolone-induced osteoporosis displayed a decreased blood pressure in the marrow cavity. In addition, a disordered action of catecholamines (norepinephrine and epinephrine) on blood pressure in the marrow cavity of osteoporotic bone was observed. Pamidronate administration in osteoporotic rats resulted in smaller increases in the blood pressure caused by norepinephrine and epinephrine in the marrow cavity of long bones.     

Effect of D-003, a mixture of very high molecular weight aliphatic acids, on prednisolone-induced osteoporosis in Sprague-Dawley rats

BACKGROUND: Drugs inhibiting cholesterol biosynthesis may affect bone metabolism through inhibition of the mevalonate pathway resulting in the inhibition of protein prenylation required for osteoclast activity. D-003 is a mixture of high molecular weight aliphatic primary acids purified from sugar-cane (Saccharum officinarum) wax, with cholesterol-lowering effects demonstrated in experimental and clinical studies. D-003 inhibits cholesterol biosynthesis through indirect regulation of HMG-CoA reductase activity. A previous study demonstrated that D-003 prevented bone loss and bone resorption on ovariectomy-induced osteoporosis in rats. Corticosteroid-induced osteoporosis is the result of changes affecting calcium homeostasis, but the hallmark of corticosteroid-induced bone loss is the direct effects on bone cells, such as inhibition of osteoblastogenesis, promotion of apoptosis of osteoblasts and osteocytes, and decrease in bone formation. OBJECTIVE: To determine whether D-003 could prevent the bone loss induced with prednisolone in Sprague-Dawley rats. METHODS: Rats were randomly distributed in five groups (ten rats per group): a sham-operated control and four groups orally treated with prednisolone 6 mg/kg for 80 days; a positive control orally treated with vehicle; and three groups orally treated with D-003 at 5, 25 and 200 mg/kg, respectively. Rats were killed, bones removed and histological variables of bone resorption and formation studied for histomorphometry. RESULTS: Compared with the sham group, prednisolone significantly (p < 0.01) reduced trabecular bone volume (TBV), while D-003 significantly (p < 0.001) and dose-dependently prevented the prednisolone-induced reduction of TBV. Treatment with prednisolone lowered (p < 0.001) trabecular thickness (TbTh) and number (TbN), while increasing (p < 0.001) the gap between trabeculae. D-003 (5, 25 and 200 mg/kg/day) significantly (p < 0.001) and dose-dependently prevented the reduction of TbTh and TbN and the increase of trabecular gap induced with prednisolone. Treatment with prednisolone increased both the surface and number of osteoclasts compared with sham (p < 0.001). D-003 (5-200 mg/day), however, prevented this effect (p < 0.001 for all comparisons). D-003 also prevented (p < 0.001) the reduction of osteoblast surface (ObS/BS) induced by prednisolone. Osteonecrotic areas were observed in all positive controls, but in none of the sham animals. Positive controls showed hypertrophy of bone marrow adipocytes and lipid-laden pluripotential stromal cells in bones. A significant and dose-dependent reduction of the frequency of animals showing prednisolone-induced osteo-necrosis was observed across the doses of D-003 (5, 25 and 200 mg/kg) investigated here. CONCLUSIONS: D-003 (5, 25 and 200 mg/kg) prevented trabecular bone loss and femoral neck osteonecrosis induced with prednisolone in Sprague Dawley rats, also increasing osteoblast surface and reducing bone resorption parameters. These results suggest that D-003 could be useful for managing corticosteroid-induced osteoporosis.