OBJECTIVE: To investigate the effects of continuous pumping of teriparatide (TPTD) on bone metabolism in ovariectomized and normal mice and provide experimental evidence for the selection of animal models for studying the effects of TPTD and its related peptides on osteoclasts. METHODS: Twenty-four female C57BL mice (6-weeks old) were subjected to ovariectomy (OVX) or sham operation followed 7 days later by continuous pumping of TPTD or the solvent vehicle (VEH) a micropump (SHAM-VEH, SHAM-TPTD, OVX-VEH, and OVX-TPTD groups; =6). Two weeks later, the tibial and femoral bones were harvested for micro-CT scanning to measure the parameters of the tibia and the femoral cortical bone. Histopathological examinations of the tibial tissue were conducted using HE staining and TRAP staining and the number of osteoclasts and the growth plate thickness were determined. The serum Ca2 + levels of the mice were measured. The primary osteoblasts from the cranial bone were treated with estradiol (E2) and TPTD for 48 h, and the expressions of β-catenin and RANKL protein in the cells were analyzed. RESULTS: The trabecular bone mass of OVX mice was significantly lower than that of sham-operated mice ( < 0.05). Continuous TPTD pumping significantly reduced tibial cancellous bone mass and femoral cortical bone area in the sham-operated mice, while in the castrated mice, TPTD pumping increased the cancellous bone mass without changing the cortical bone area. TRAP staining showed that cancellous osteoblasts in the tibia increased significantly in the castrated mice as compared with the sham-operated mice, and TPTD pumping significantly increased the number of cancellous osteoblasts in the sham-operated mice ( < 0.05). In the primary cultured osteoblasts, treatment with both E2 and TPTD obviously lowered the expression of β-catenin and increased the expression of RANKL as compared with TPTD treatment alone. CONCLUSIONS Continuous pumping of TPTD promotes bone resorption in normal mice but does not produce obvious bone resorption effect in the ovariectomized mice, suggesting that castrated mice are not suitable models for studying the effect of TPTD and the related peptides on the osteoclasts.
Animals ; Bone Density ; Bone Density Conservation Agents ; administration & dosage ; pharmacology ; Bone Resorption ; drug therapy ; Bone and Bones ; drug effects ; metabolism ; Female ; Growth Plate ; drug effects ; Mice ; Mice, Inbred C57BL ; Osteoclasts ; drug effects ; Ovariectomy ; RANK Ligand ; metabolism ; Teriparatide ; administration & dosage ; pharmacology ; beta Catenin ; metabolism

The L-gulono-gamma-lactone oxidase gene (Gulo) encodes an essential enzyme in the synthesis of ascorbic acid from glucose. On the basis of previous findings of bone abnormalities in Gulo-/- mice under conditions of ascorbic acid insufficiency, we investigated the effect of ascorbic acid insufficiency on factors related to bone metabolism in Gulo-/- mice. Four groups of mice were raised for 4 weeks under differing conditions of ascorbic acid insufficiency, namely, wild type; ascorbic acid-sufficient Gulo-/- mice, 3-week ascorbic acid-insufficient Gulo-/- mice, and 4-week ascorbic acid-insufficient Gulo-/- mice. Four weeks of ascorbic acid insufficiency resulted in significant weight loss in Gulo-/- mice. Interestingly, average plasma osteocalcin levels were significantly decreased in Gulo-/- mice after 3 weeks of ascorbic acid insufficiency. In addition, the tibia weight in ascorbic acid-sufficient Gulo-/- mice was significantly higher than that in the other three groups. Moreover, significant decreases in trabecular bone volume near to the growth plate, as well as in trabecular bone attachment to the growth plate, were evident in 3- or 4-week ascorbic acid-insufficient Gulo-/-. In summary, ascorbic acid insufficiency in Gulo-/- mice results in severe defects in normal bone formation, which are closely related to a decrease in plasma osteocalcin levels.
Animals ; Ascorbic Acid* ; Down-Regulation* ; Glucose ; Growth Plate ; L-Gulonolactone Oxidase ; Metabolism ; Mice ; Osteocalcin* ; Osteogenesis* ; Plasma ; Tibia ; Weight Loss

PURPOSE: Pathologic changes in the growth plate remain unknown in Legg-Calve-Perthes (LCP) disease. Spontaneously hypertensive rats have proven to be a good model for studying LCP disease. This study investigated the histopathologic changes and the expression of vascular endothelial growth factor in the growth plate of spontaneously hypertensive rats (SHR). MATERIALS AND METHODS: Sixty SHR rats were divided into two groups: those showing osteonecrosis (SHR+n group: 32), and those showing normal ossification (SHR-n group: 28). Thirty Wister Kyoto rats served as a control. For histomorphological measurement, the length of each zone of the growth plate was measured. Cell kinetics was measured by 5-bromo-2'-deoxyuridin (BrdU) immunohistochemistry and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assays. Vascular endothelial growth factor (VEGF) immunohistochemistry was used to identify of expression of VEGF. RESULTS: The lengths of growth plates of the SHR+n group were significantly shorter in the initial growth period than those of the other groups. The lowest proliferative rate and the highest apoptosis rate were observed in the SHR+n group at the initial growth period. The expression of VEGF in the growth plate of the SHR group was lower than the control group, and it was lower in the SHR+n group than in the SHR-n group. CONCLUSION: The growth plate of the SHR+n group was found to be affected by disease process of ischemic necrosis of the femoral head, and this might explain the relative overgrowth of the greater trochanter in the later stages of LCP disease.
Animals ; Apoptosis ; Femur Head/metabolism/*pathology ; Femur Head Necrosis/metabolism/pathology ; Growth Plate/*cytology/metabolism ; Osteogenesis/physiology ; Rats ; Rats, Inbred SHR ; Rats, Sprague-Dawley ; Vascular Endothelial Growth Factor A/metabolism

BACKGROUND: Compressive force across the growth plate may cause retardation and even arrest of physeal growth. The purpose of this study was to investigate histologic changes, metabolic changes in terms of glycosaminoglycan (GAG) concentration, and contrast-enhanced micro-computed tomography (CEMCT) findings of physeal cartilage in a rabbit model of physeal damage caused by excessive compression. METHODS: Compressive forces were applied via external fixators for two weeks to the growth plates of distal femurs and proximal tibiae of right hind-legs in 8-week-old rabbits. Left hind-legs remained intact and were used as controls. Forty-four bone specimens containing growth plates of distal femurs or proximal tibiae were harvested one week (n = 12) and four weeks (n = 32) after surgery, and examined for histologic findings (H&E staining) and GAGs quantification in physeal cartilage. After incubation in an ionic contrast material for 48 hours, specimens were scanned by CEMCT, and the pixel values of physeal cartilage were measured. RESULTS: CEMCT showed a thin, highly attenuated line parallel to the growth plate in compressed specimens harvested at four weeks after surgery, which was found to be transversely connected trabecular bone. In these specimens, GAG content in physeal cartilage was significantly lower, and CEMCT pixel values of physeal cartilage were significantly higher than in the specimens from the contralateral control side. CONCLUSIONS: Excessive compressive force applied to growth plates produces altered histologic features and metabolic function in terms of decreased GAG content in physeal cartilage, changes that can be demonstrated by CEMCT.
Animals ; Growth Plate/*growth & development/metabolism/*pathology/radiography ; Male ; Pressure ; Rabbits ; X-Ray Microtomography

OBJECTIVETo observe the morphology and phenotypes of cells extracted from the endplate in the intervertebral discs and identify the factors affecting their biological characteristic.

METHODSThe intervertebral disc endplate were digested enzymatically, and the morphology of the obtained cells was examined under light microscope. Immunhistochemical analysis of collagen II and real-time PCR was carried out, and the morphologies, viability, cell growth, apoptosis and chondrocyte matrix production were compared between the cells isolated from the degenerative and normal vertebral endplates.

RESULTSThe cells in primary culture presented with spherical and oval morphology, and the cytoplasm was stained blue with toluidine blue. The morphologies of the cartilage endplate cells and the articular cells were almost identical. All the freshly isolated cells expressed collagen II. The degenerative vertebral endplate cells showed decreased expression of collagen II with increased apoptotic cells as compared with normal vertebral endplate cells.

CONCLUSIONThe intervertebral disc endplate cells, like articular cartilage cells, express cartilage-specific matrix proteins. Degenerative vertebral endplate cells show decreased cell vitality with increases cell apoptosis.

Adult ; Apoptosis ; physiology ; Cartilage ; metabolism ; pathology ; Cells, Cultured ; Chondrocytes ; metabolism ; pathology ; Collagen ; metabolism ; Female ; Growth Plate ; metabolism ; pathology ; Humans ; Intervertebral Disc ; metabolism ; pathology ; Intervertebral Disc Degeneration ; metabolism ; pathology ; Lumbar Vertebrae ; metabolism ; pathology ; Male ; Young Adult

OBJECTIVETo investigate the effects and the mechanisms of stanozolol (ST) on the proliferation, maturation and differentiation of in vitro cultured growth plate chondrocyte isolated from gonadotropin releasing hormone analogue (GnRHa)-treated adolescent rats, to study if ST mediates the proliferation of chondrocytes via the estrogen receptor alpha (ERalpha), androgen receptor (AR) and/or insulin-like growth factor-1 receptor (IGF-1R) and interactions of the two receptor and IGF-1R receptor signaling pathway, to investigate the mechanism of the biological effects in ST promoting bone growth/maturity at molecular level.

METHODThe rats were weaned at the end of 3 weeks and intramuscular injection of triptorelin of GnRHa preparations, qow x 2 was started. The rats were sacrificed at the end of 7 weeks, and then the tibiae growth plates were taken out with sterile procedure. The chondrocytes were obtained by two-time enzyme digestion method, and the experiments were carried out with the primary chondrocytes. Immunohistochemical staining of proliferating cell nuclear antigen (PCNA) and Western blot analysis were applied.

RESULTThe results of PCNA demonstrated that stanozolol enhanced the proliferation of the chondrocytes, time-course studies showed that the proliferation were maximally stimulated by stanozolol after 2 days of incubation and decreased again after longer periods of incubation. The expression of p-ERalpha, p-IGF-1R and p-extracellular-signal regulated kinase 1/2 (ERK1/2) increased with the incubation period of ST treatment, and reached the peak value at a certain time, and then gradually decreased. The expression of p-ERalpha, p-IGF-1R and p-ERK1/2 increased with the elevation of ST concentration, and reached the peak value at 10(-9) - 10(-8) mol/L, then gradually decreased. ST induced-p-ERalpha expression was partially blocked by ERalpha and mitogen-activated protein kinase kinase inhibitors. ST induced-p-IGF-1R expression was partially blocked by ERalpha and IGF-1R inhibitors. ST induced-p-ERK1/2 expression was partially blocked by mitogen-activated protein kinase kinase and IGF-1R inhibitors.

CONCLUSIONAs an androgen derivation, ST exerts its biological effects of promoting proliferation of the long bone growth plate chondrocytes via activating the classic ERalpha receptor pathway and mitogen-activated protein kinase pathway, and at the same time, by activation of IGF-1R. Both IGF-1R and ERalpha can promote "cross-talk" of two systems' receptor signal through mitogen-activated protein kinase signal pathway.

Androgens ; pharmacology ; Animals ; Cells, Cultured ; Chondrocytes ; cytology ; drug effects ; metabolism ; Estrogen Receptor alpha ; metabolism ; Female ; Growth Plate ; drug effects ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Rats ; Receptor Cross-Talk ; Receptor, IGF Type 1 ; metabolism ; Signal Transduction ; drug effects ; Stanozolol ; pharmacology

OBJECTIVETo observe the effects of Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine on vascular endothelial growth factor (VEGF) in growth retardation induced by Decamethasone and observe its mechanisms.

METHODSThirty one-month-old New Zealand white rabbits were randomly divided into normal group, dexamethasone-treated group and Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine-treated group. The rabbits in dexamethasone group and Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine-treated group received dexamethasone (5 mg/kg x d). The rabbits were sacrificed at the 6th and 12th week after administration, and then rabbit tibia articular was removed. (1) Using TUNEL stain to detect apoptotic index. (2) Using immunohistochemical stain to detect the positive index of the expression of vascular endothelial growth factor (VEGF) in the epiphyseal cartilage of growth. (3) Using fluorescent quantitative PCR to detect the expression intensity of VEGF mRNA in each group.

RESULTSAt the 6th and 12th week after administration, there were significant difference in apoptotic index and cell proliferation index between dexamethasone group and normal group (P<0.01, dexamethasone group more than normal group). Immunohistochemical stain and fluorescent quantitative PCR indicated that the expression of VEGF and VEGF mRNA in dexamethasone group was significantly decreased as compared with that in normal group (P<0.01), and also obviously lower than Chinese herbal medicine-treated group (P<0.01).

CONCLUSIONVEGF has 2. an important role during the growth retardation induced by Dexamethasone. Nourishing yin clearing heat ([Chinese characters: see text]) Chinese herbal medicine can reduce the growth retardation induced by Dexamethasone through increasing the VEGF expression in growth plate chondrocytes and then increase angiogenesis.

Animals ; Apoptosis ; Cell Proliferation ; Dexamethasone ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Female ; Gene Expression ; drug effects ; Growth Plate ; cytology ; drug effects ; growth & development ; metabolism ; Male ; Rabbits ; Random Allocation ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

OBJECTIVETo investigate the effect of Chinese herbs for nourishing yin and removing fire (NYRF) on gene expressions of estrogen receptor alpha (ER alpha), insulin-like growth factor-1 receptor (IGF-1R) and epithelial growth factor receptor (EGFR) in the epiphyseal growth plate of the female pubertal rats.

METHODSThe rats were randomly divided into the control group and the intervened group. Immunohistochemistry and realtime-PCR methods were used to measure the gene expression of ER alpha, IGF-1R and EGFR and their protein synthesis in epiphyseal growth plate.

RESULTSAfter being intervened with NYRF, the gene expressions of ER alpha and IGF-1R were down-regulated and their protein synthesis markedly reduced, while those of EGFR were unchanged.

CONCLUSIONNYRF can modulate the development and maturation of bone by regulating the expressions of ER alpha and IGF-1R in the epiphyseal growth plate.

Animals ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Estrogen Receptor alpha ; genetics ; metabolism ; Female ; Gene Expression ; drug effects ; Growth Plate ; drug effects ; metabolism ; Humans ; Protein Biosynthesis ; drug effects ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptor, Epidermal Growth Factor ; genetics ; metabolism ; Receptor, IGF Type 1 ; genetics ; metabolism ; Yin-Yang

PURPOSE: To examine the effects of change in the weight bearing on the growth plate metabolism, a simulated animal model of weightlessness was introduced and the chondrocytes' cellular kinetics were evaluated. MATERIALS AND METHODS: Unloading condition on the hind-limb of Sprague-Dawley rats was created by fixing a tail and lifting the hind-limb. Six rats aged 6 weeks old were assigned to each group of unloading, reloading, and control groups of unloading or reloading. Unloading was maintained for three weeks, and then reloading was applied for another one week thereafter. Histomorphometry for the assessment of vertical length of the growth plate, 5-bromo-2'-deoxyuridin (BrdU) immunohistochemistry for cellular kinetics, and biotin nick end labeling TUNEL assay for chondrocytes in the growth plate were performed. RESULTS: The vertical length of the growth plate and the proliferative potential of chondrocytes were decreased in the unloading group than those of control groups. Inter-group differences were more significant in the proliferative and hypertrophic zones. Reloading increased the length of growth plate and proliferative potential of chondrocytes as evidenced by increase of the ratio of positive BrdU stained cells. However, apoptotic changes in the growth plate were not affected by the alterations of weight bearing. CONCLUSION: Alterations in the weight bearing induced changes in the chondrocytic proliferative potential of the growth plate and have no effects on the apoptosis occurred. This may suggest that deprived weight bearing due to various clinical situations hamper normal longitudinal bone growth, and further studies regarding the factors for reversibility of chontrocytic proliferation upon variable mechanical stresses are needed.
Animals ; Apoptosis ; Biotin ; Bone Development ; Bromodeoxyuridine ; Chondrocytes ; Growth Plate* ; Immunohistochemistry ; In Situ Nick-End Labeling ; Kinetics* ; Lifting ; Metabolism ; Models, Animal ; Rats ; Rats, Sprague-Dawley ; Stress, Mechanical ; Tail ; Weight-Bearing* ; Weightlessness

"Rickets" is the term applied to impaired mineralization at epiphyseal growth plate, resulting in deformity and impaired linear growth of long bones. Rickets may arise as a result of vitamin D deficiency or abnormality in metabolism. Vitamin D-dependent rickets (VDDR) is rare autosomal recessive disorder in which affected individuals have clinical features of vitamin D deficiency. In 1961, Prader first described this disorder including severe clinical features of rickets, such as hypophosphatemia, hypocalcemia, muscle weakness and seizure. Two distinctive hereditary defects, type I VDDR and type II VDDR have been recognized in vitamin D metabolism. Type I VDDR may be due to congenital defects of renal 1 alpha-hydroxylase, the enzyme responsible for conversion of 25 (OH) D3. These patients have low to detectable 1,25(OH)2D3 in presence of normal to raised 25 (OH) D3. In type II VDDR, renal production of 1,25(OH)2D3 is intact but 1,25(OH)2D3 is not used effectively and target organ resistant to 1,25(OH)2D3 is respectively derived from the abnormality in the vitamin D receptor. We report a case of a 25 month-old girl with typical clinical features of VDDR type I rickets, hypocalcemia, increased alkaline phosphatase and secondary hyperparathyroidism.
Alkaline Phosphatase ; Child, Preschool ; Congenital Abnormalities ; Female ; Growth Plate ; Humans ; Hyperparathyroidism, Secondary ; Hypocalcemia ; Hypophosphatemia ; Metabolism ; Muscle Weakness ; Receptors, Calcitriol ; Rickets* ; Seizures ; Vitamin D ; Vitamin D Deficiency ; Vitamins*