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

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 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