Effect Of Raloxifene On Cadmium In Kidney Of Ovariectomy Rats And Renal Tubular Cell

Objective： To investigate the effect of Raloxifene on ERa、ER p andMT-la expression in kidney of rats and renal tubular cell contaminated withcadmium, for exploring the protective effect and action mechanism ofRaloxifene in the prevention and treatment of cadmium poisoning. Methods：①Animalpart: A total of32female Sprague-Dawley rats were randomlydivided into4groups: the sham-operated group (sham), the ovariectomizedgroup(OVX), the cadmium group, the raloxifene group, with8rats in eachgroup. Determination of rat serum estradiol by radioimmunoassay methodamong four groups, the levels of (32-microglobulin by Elisa. Determination ofblood cadmium and urine cadmium by graphite furnace atomic absorptionspectrometry; the levels of ERp, MT-la mRNA and protein expression wereexamined in renal tissue by PCR and immunohistochemistiy technology.②Cellpart: The kidneys of young SD rat were processed to separate and puriyfthe renal tubule cells by Percoll. Select the second generation cells forexperiment. The experiment was divided into3groups: Blank group, CadmiumChloride group, Raloxifene group. After4hours, the cell viabiliyt was detectedby MTT, and after24hours, the levels of ERa,ER(3, MT-la mRNA and proteinexpression were examined in renal tissue by PCR and immunohistochemistrytechnology. Results：①Animal parts: Compared with the OVX group, thelevel of estrogen decreased significantly in cadmium group (尸<0.05), the wetweight of kidney, kidney coefficient, urinary [32-MG, blood cadmium andurinary cadmium levels were elevated in the cadmium group(P<0.05), renal pathology showed that renal tubule appeared degenerative diseases, renalinterstitial large oozing of blood, RT-PCR and immunohistochemistry showedthat the ER (3and MT-la protein levels also increased (P<0.05). Compared withthe cadmium group, the levels of estrogen were significantly increased in theraloxifene group (户<0‘05)，urinary (32-microglobulin, blood cadmium andurinaiy cadmium levels were decreased (P<0.05), the damage of renal tubuleswas reduced, occasionally degenerative disease, the levels of ER p and MT-laprotein expression were decreased (尸<0.05)，and both were positively correlated(r=0.387, P<0.05). But ERa showed no significant increase in cadmium groupand raloxifene group (尸>0.05)?②Cell part: Compared with the blank group,most of the cell morphology were changed in cadmium chloride group, most ofthe cell were death, the survival rate only55.3%. PCR andimmunohistochemistry showed that the expression of ER (3, MT-la protein wereincreased (户<0.05). Compared with cadmium chloride group, only a small partof cell morphology was changed in Raloxifene group, the survival rate up to88.6%. At the same time, the expression of ER (3，MT-la mRNA and proteindecreased (P<0.05). The expression of ERa showed no significant increaseamong three groups (尸>0.05). Conclusion： Cadmium showestrogenic-mimetic action on kidney, it maybe combine with ERp in kidney tostimulate MT-la expression, which can form Cd-MT compound to injury renaltubule. Raloxifene can antagonize it, and it also can reduce renal damage. It maybe associated with Raloxifene compete with renal ER{3and down-regulation ofMT-la, decrease of Cd-MT synthesis, so as to reduce the sensitivity of kidney tocadmium.