[The effect of different concentrations of fluoride on the expression of Smad2/3 in ameloblast of rat incisor].

PURPOSE: To investigate the effect of different concentrations of fluoride on the expression of Smad2/3 which is a specific intracellular signal transduction molecule of TGF-ß, and to explore the mechanism of dental fluorosis in rat. METHODS: Forty Wistar rats were randomly divided into 3 groups.HE and immunohistochemistry were used to detect the changes of the ameloblasts and the expression of Smad2/3 in rat incisors. MetaMorph microscope images analysis system and SPSS12.0 software package were used to analyze the images and data. RESULTS: Typical symptoms of dental fluorosis were found in the fluoride group. The expression of Smad2/3 in the ameloblasts in the experimental group was significantly lower than that in the control group (P<0.01); but the difference was not significant between the low-dose group and high-dose group(P>0.05). CONCLUSIONS: By inhibiting the expression of Smad2/3 in ameloblasts, fluoride affects the differentiation and development of enamel,leading to the occurrence of dental fluorosis in rat.

[Effect of fluoride on the expression of MMP-20/TIMP-2 in ameloblast of rat incisor and the antagonistic effect of melatonin against fluorosis].

PURPOSE: To study the effect of concentration of fluoride on the expression of matrix metalloproteinase-20(MMP-20) and tissue inhibitors of metalloproteinase-2 (TIMP-2) in the ameloblast of rat incisor,and explore the formation mechanism of dental fluorosis. By comparing the different expression of MMP-20,TIMP-2 between fluoride group and the melatonin group,to decide whether melatonin has antagonitic effect on dental fluorosis. METHODS: Forty Wistar rats were randomly divided into 6 groups. The groups were as follows: control group,low-dose group, high-dose group,normal saline group and melatonin group. The animals were sacrificed 10 weeks after treatment. HE and immunohistochemical staining were used to observe the changes of ameloblasts and the expression of MMP-20 and TIMP-2 in rat incisors. MetaMorph microscope images analysis system was used to analyze the images, and SPSS12.0 software package was used for data analysis. RESULTS: The surface of rat incisors fed with fluoride had chalky color change and cross stritations could be seen on the enamel surface.In the fluoride group,the ameloblasts were disarranged, cells arranged in multi-layer,even showing vacuolar change.The changes in the high-dose group was severer than the low-dose group. MMP-20, TIMP-2 were expressed both in the secretory ameloblasts, and in the odontoblasts.The expression of MMP-20 in rat's ameloblasts in the experimental group was significantly lower than that in the control group (P < 0.01); and no significant difference was found between the low-dose and high-dose groups(P > 0.05). The difference of expression of TIMP-2 was not significant among all the groups. The difference of expression of MMP-20 and TIMP-2 was not significant between the melatonin and the fluoride groups. CONCLUSIONS: The excessive fluoride can inhibit the secretion of MMP-20 and disturb the balance between MMP-20 and TIMP-2,which lead to the delay of amelogenin removal and enamel demineralization. Melatonin has no antagonistic effect on the dental fluorosis. Supported by National Natural Science Foundation of China (30600509) and Natural Science Foundation of Liaoning Province (20102278).

Transplanted bone marrow stromal cells migrate, differentiate and improve motor function in rats with experimentally induced cerebral stroke.

Bone marrow stromal cells are multipotential cells that can be induced to differentiate into osteoblasts, chondrocytes, myocytes and adipocytes in different microenvironments. Recent studies revealed that bone marrow stromal cells could improve neurological deficits of various damages or diseases of the central nervous system such as Parkinson's disease, brain trauma, spinal cord injury and multiple sclerosis, and promote glia-axonal remodeling in animal brain subjected to an experimentally induced stroke. In the present study, bone marrow stromal cells were intracerebrally transplanted into the cerebrum following a transient middle cerebral artery occlusion. Our aim was to find out whether the bone marrow stromal cells could survive and express neural phenotypic proteins and, in addition, whether they could restore the behavioral and functional deficits of the cerebral ischemic rats. Our results demonstrated that transplanted bone marrow stromal cells survived and migrated to areas around the lesion site. Some of them exhibited marker proteins of astrocytes and oligodendrocytes. Bone marrow stromal cell implantation significantly reduced the transient middle cerebral artery occlusion-induced cortical loss and thinning of the white matter and enhanced cortical beta-III-tubulin immunoreactivity. Rats implanted with bone marrow stromal cells showed significant improvement in their performance of elevated body swing test and forelimb footprint analysis and only transient recovery of the adhesive-removal test. Our data support bone marrow stromal cells as a valuable source of autologous or allogenic donor cells for transplantation to improve the outcome following cerebral ischemia.