Study On The Intervention Mechanism Of Calcium To The Bone Tissue Of Lead-exposed Rats

[Objective] To investigate the effects of different doses of calcium on rats bone metabolism changes at molecular and cellular levels caused by lead exposure. To provide theoretical basis of the supplement of calcium is helpful to minimize Lead poisoning.[Methods] In the test, 50 healthy 7 days old male rats were randomly divided into five groups, and named as control group (normal diet, distilled water), lead exposed group (normal diet,0.2% (CH3COO)2Pb-water), Test Ⅰ group (0.5% Ca, 0.2% (CH3COO)2Pb-water), Test Ⅱ group (1% Ca, 0.2% (CH3COO)2Pb-water) and Test Ⅲ group (2% Ca, 0.2% (CH3COO)2Pb-water), respectively. After 60 days, the blood and bone of the rats were collected and the weights were weighed. The osteocalcin and parathormone levels and alkaline phosphatase activity in serum were also detected. The contents of Pb, Ca, Zn, Cu, Mg, Fe and Mn in bone were determined by ICP. The bone histopathological changes were observed by HE stain. In addition, the expression levels of TRPV5, TRPV6, NCX1 and PMCAlb were researched by real-time RT-PCR.[results] (1) Compared with control group, the body weight in lead exposed group was significantly decreased (P<0.01) from the 17th day; Compared with lead exposed group, the body weight were extractly significant increased (P<0.01) from the 21 th day in test Ⅱ group and were significantly decreased(P<0.05) from the 41th day in test Ⅲ group.Compared with control group, BGP contents and AKP activity in serum of lead exposed group were extractly significant decreased (P<0.05 or P<0.01), PHT contents was significantly increased (P<0.01); Compared with lead exposed group, BGP contents and AKP activity in test groups were increased, the AKP activity in test I group was significant level (P<0.05), BGP contents and AKP activity in test Ⅱ group were significant levels (P<0.05), PHT contents in test groups were decreased, test Ⅱ group was extractly significant level (P<0.01).(2) Compared with control group, Pb in bone of lead exposed group was much significantly increased (P<0.01), Ca, Zn, Cu, Fe contents were significantly decreased(P<0.05 or P<0.01), Mg and Mn contents were decreased, but there were no significant difference; Compared with lead exposed group, Pb contents in test Ⅰ and test Ⅱ groups were significantly decreased(P<0.01), Ca, Cu contents in test Ⅱ group were significantly increased(P<0.05), Ca contents in test Ⅲ group was much significantly increased(P<0.01).Compared with normal control group, in lead exposed group, the bone marrow cavity enlarged; bone trabecular sparse, distributed unevenly, atrophy and not smooth, partial disappear, different shapes trabecular in the edge; the level of osteoblast decrease, whereas osteoclasts increase. Compared with lead exposed group, the bone marrow cavity shrink; the bone trabecular number increase and got smooth; the level of osteoclasts decrease. The better effect is test Ⅱ group.(4) Compared with control group, the mRNA expression level of TRPV5 and TRPV6 in lead exposed group were significantly decreased (P<0.01), the mRNA expression level of NCX1 and PMCAlb in lead exposed group were significantly increased (P<0.01); Compared with lead exposed group, the mRNA expression level of TRPV5 and TRPV6 in test I group were significantly increased (P<0.05), but the mRNA expression level of NCXl in test Ⅰ group was significantly decreased (P<0.05), the mRNA expression level of TRPV5 and TRPV6 in test Ⅱ group were extractly significant increased (P<0.01), but the mRNA expression level of NCX1 and PMCAlb in test Ⅱ group were significantly decreased (P<0.05 or P<0.01), the mRNA expression level of TRPV6 in test Ⅲ group was significantly increased (P<0.05), but the mRNA expression level of NCXl in test Ⅲ group was significantly decreased (P<0.05).[Conclusion] In conclusion, the results of the present study demonstrated that the calcium could control bone metabolism related biochemical indicators in rats and alleviate the plumbism. Meanwhile, it could regulate the expression of TRPV5, TRPV6, NCX1 and PMCAlb genes. These findings could signify that calcium could relieve the bone injury caused by plumbum.