Excess genistein suppresses the synthesis of extracellular matrix in female rat mandibular condylar cartilage.

AIM: To investigate the effect of excess genistein on the extracellular matrix in mandibular condylar cartilage of female rats in vivo. METHODS: Female SD rats were administered through oral gavage with genistein (50 mg/kg) or placebo daily for 6 weeks. The morphological changes of temporomandibular joints were studied with HE staining. The expression of cartilage matrix compounds (aggrecan and collagen type II), estrogen-related molecules (aromatase, estradiol, ERα and ERß) and proliferating cell nuclear antigen (PCNA) in mandibular condylar cartilage was detected using immunohistochemistry, ELISA and real-time PCR. RESULTS: The genistein treatment significantly reduced the thickness of the posterior and middle regions of mandibular condylar cartilage, and decreased the expression of collagen type II, aggrecan and PCNA. Compared with the control group, the estradiol content and expression levels of the key estradiol-synthesizing enzyme aromatase in the genistein-treatment group were significantly decreased. The genistein treatment significantly increased the expression of ERß, but decreased the expression of ERα. CONCLUSION: Excess genistein suppresses extracellular matrix synthesis and chondrocytes proliferation, resulting in thinner mandibular condylar cartilage. These effects may be detrimental to the ability of mandibular condylar cartilage to adapt to mechanical loads.

Dose-dependent effects of genistein on bone homeostasis in rats' mandibular subchondral bone.

AIM: To investigate the effect of genistein on bone homeostasis in mandibular subchondral bone of rats. METHODS: Female SD rats were administered with genistein (10 and 50 mg/kg) or placebo by oral gavage for 6 weeks. Then the animals were sacrificed, and histomorphology and micro-structure of mandibular condyle were examined using HE staining and micro-CT analysis, respectively. The expression levels of alkaline phosphatase (ALP), osteocalcin (OC), osteoprotegerin (OPG), the receptor activator of nuclear factor κB ligand (RANKL) and estrogen receptors (ERs) in mandibular condyle were detected using real-time PCR. Cultured osteoblasts were prepared from rat mandibular condyle for in in vitro study. The cells were treated with genistein (10(-7) or 10(-4) mol/L) for 48 h. The expression of the bone homeostasis-associated factors and estrogen receptors (ERs) was detected using real-time PCR, and ER silencing was performed. RESULTS: At both the low- and high-doses, genistein significantly increased the bone mineral density (BMD) and bone volume, and resulted in thicker subchondral trabecular bone in vivo. In both in vivo and in vitro study, the low-dose genistein significantly increased the expression of ALP, OC and OPG, but decreased the expression of RANKL and the RANKL/OPG ratio. The high-dose genistein decreased the expression of all these bone homeostasis-associated factors. Both the low and high doses of genistein significantly increased the expression of ERß, while ERα expression was increased by the low dose genistein and decreased by the high dose genistein. ERß silencing abrogated most of the effects of genistein treatment. CONCLUSION: In rat mandibular condylar subchondral bone, low-dose genistein increases bone formation and inhibit bone resorption, while excess genistein inhibits both bone formation and resorption. The effects of genistein were predominantly mediated through ERß.

[Expression feature and bioinformatic analysis of molar root patterning gene 1].

OBJECTIVE: To examine the expression of molar root patterning gene 1 (Mrp1) and predict the Mrp1 structure by bioinformatics analysis. METHODS: A pair of Mrp1-specific PCR primers were designed, and RT-PCR method was used to study the mRNA's expression pattern in rat molar root and other organs. Gene positioning and other protein sequence prediction were carried out by chromosome analysis and other bioinformatics analysis. RESULTS: Mrp1 was expressed not only in the molar but also in the developing pancreas, liver, lung and kidney tissues. Mrp1 was located in the 18q12.3 chromosome of the rats and the Mrp1 amino acids sequence had about 37% homology with a known protein Uroplakin IIIb (p35) which was an urothelial differentiation membrane molecular marker. A trans-membrane structure, 5 PKC phosphorylation sites and 4 CKII phosphorylation sites in Mrp1 were found. CONCLUSIONS: Mrp1 has a broad expression in different developing organs, and it may have a important function in the rat tooth root development.