Study On The Expression And Modulation Of Matrix Gla Protein In The Aorta And Lumbar Vertebra In Ovariectomized SD Rats

Objective:Observe the expression of Matrix Gla Protein(MGP) in the arteries and bone of ovariectomized rats, and the regulation of drugs (estrogen,VitaminK2 and PTH),to elucidate the function of MGP in nosogeny of angiosteosis and postmenopausal osteoporosis(PMOP).Methods:Sixty Sprague-Dawley female rats were allocated into five groups randomly,12 in each:sham operation group(sham group), ovariectomized group(OVX group) ovariectomized and estrogen treatment group (E group),ovariectomized and VitaminK2 treatment group(VK2 group),ovariectomized and parathyroid hormone treatment group(PTH group).E group were injected intramscularly Estradiol Benzoate(0.2mg/kg,every other day),VK2 group were administered orally with Vitamin K2 (30mg/kg/d,5 times a week), PTH group were injected subcutaneously (20uk/kg,3 times a week)after three weeks of ovariectomy for 12 weeks. All rats were kept the serum and urine before and after ovariectomized every three weeks. All rats were sacrificed after 18 weeks. Uterus,arteries and lumbar vertebral bones were observed by histochemical method.Bone mineral density(BMD)of lumbar vertebra of rats was determined by DEXA.The content of MGP in serum and urine and the content of estrogen was determined by enzyme-linked immunosorbent assay(ELISA).The aortic calcium content were evaluated.Expression of Undercarboxylated Matrix Gla Protein (ucMGP) was detected by immunochistochemistry. Calcium accumulation in media of aorta were measured by Von Kossa staining. Relative quantification of MGP mRNA expression in aorta and lumbar vertebra bone was detected by Fluorescent real-time quantitative polymeruse chain reaction (RT-PCR).Results:(1) Osteoporosis rats modle:After 18 weeks of ovariectomized, the pathological section of uterus,aortic,lumbar vertebra have differernt variation in different groups;The BMD of lumbar vertebra inVK2 group reduced than OVX group,which had no statistical difference. The BMD in OVX group were lower than those in sham Group,E group and PTH group significantly (P<0.05); The content of estrogen in serum have no difference before ovariectomized. Before sacrifice,the content of estrogen of sham group have no change,the other groups reduced (P<0.05).(2)The content of MGP in serum:there are no difference before ovariectomized.Afeter ovariectomized,the content of MGP in serum and urin of model group reduced.The content of MGP in serum of OVX group decreased dramatically than other groups,which in drug treated group lightly reduced and then increased.The content of MGP in urin kept constant from 3 to 12 weeks after drug treated and then increaded.The content of MGP in serum and urin of sham group had no significant variance.(3)Total calcium content in aortic vascular of OVX group increased compared with other groups,and sham group reduced compared with OVX group.(4) Immunohistochemical localization of ucMGP and Von Kossa staining in arterial vessel wall.Immunochistochemical localization of ucMGP can be seen in calcium localization, but the size of ucMGP localized in OVX were more than other groups in both aortic vascular and lumbar vertebra. (5) Relative expression of MGP in the aorta and lumbar vertebra:Relative quantification of MGP mRNA expression in aorta of OVX group was significantly less than other groups(P<0.01), which in sham group was more than other groups(P<0.01).Relative quantification of MGP mRNA expression in lumbar vertebra opposited to that in aorta.(6)There were correlation between total calcium content,BMD, the relative expression of MGP in the aorta and lumbar vertebra.Conclusion:(1)The descent of estrin is the main reason of vascular calcification and OP in postmenopause women.(2)Expression of MGP gene and protein have an important effect in commoned nosogenesis of vascular calcification and OP.(3) Estrogen,Vitamin K2 and PTH could improve both vascular calcification and OP of OVX rats,which may depend on the regulation of MGP gene and protein expression.MGP may be the target point of drug treatment.(4)Estrogen,Vitamin K2 and PTH may be used to therapied vascular calcification in clinic.