Treatment On Rabbit With Chronic Cadmium Intoxication Utilized Intravenous Infusion Of GMDTC And Its Side-effect

Research BackgroundSoil Cd (Cadmium, Cd) pollution is one of the most prominent of the current environmental problems. According to the 2014 "national survey of soil pollution bulletin", we could see the point excessive rate of soil cadmium pollution was 7.0% (450,000 square kilometers), topped the inorganic pollution; According to statistics, cadmium exceeded rate of rice, vegetables, meat, aquatic products and other edible fung was 14.6% to 21.4%, everyone may become the victim of cadmium pollution. Mass social events caused by cadmium pollution and cadmium poisoning had occurred in Hunan, Guangxi, Guangdong, Jiangxi, Liaoning, Guizhou and so on, Some villagers in mines rivers cadmium exceeded more than 70%, and poisoning death cases had occurred.The main target organ of cadmium is kidney. Cadmium can gradually accumulate in renal tubular cells, inhibit the vitamin D metabolism and reabsorption of calcium, which lead to the body loss calcium, causing osteoporosis, severe pain in the joints, which called "Itai-itai disease", and further can cause kidney failure, diabetes, cancer and so on. The body lacks of effective mechanism of clearing cadmium, Cadmium in the body is difficult to be excreted, and the biological half-life has 36 years, There is no effective drug to drive cadmium.The new complexing agent N-(2,3,4,5,6-five hydroxyhexyl) N-dithio sodium base-methionine sodium (GMDTC) of cadmium poisoning specific antidote was developed by Tang Xiaojiang (Chinese patent number:200510035377.1). Rats and mice animal experiments showed, the effect of GMDTC drive cadmium was good and low toxicity, it was no significant effect on normal ion such as Ca2+, Zn2+, Mg2+ and so on. But in the past experiments were performed by intraperitoneal injection route of administration, dosing for 4 weeks kidney cadmium drive rate was 48%. Whereas, it is different with the clinical treatment that took intravenous route of administration, and its drive cadmium rate was still not ideal. According to GMDTC drive cadmium mechanism hypothesis proposed by Tang Xiaojiang recently, GMDTC may use kidney-glucose reabsorption way to achieve drive cadmium. Taking intravenous approach may significantly improve the effect of drive cadmium, Shorten the drive cadmium time significantly, kidney cadmium purge rate will be significantly improved, and is consistent with clinical treatment approach on cadmium poisoning. Given on the rats and mice were unable to meet the intravenous route of administration, the cost of pigs, dogs, monkeys and other large animals was too high, Therefore rabbit was choosed as a model animal in this study. According to the pre-experimental research foundation, taking GMDTC 1-4 weeks by ear vein infusion method to treat chronic cadmium poisoning rabbit model, comparing the effects of drive cadmium and its toxicity, preliminary determining the time-dose-response relationship, and to provide a scientific basis for the clinical application of GMDTC.ObjectiveTo explore the drive cadmium treatment on rabbit with chronic Cadmium intoxication utilized intravenous infusion of GMDTC and its side-effect.Methods1. A factorial design trial of preparing chronic cadmium poisoning rabbit modelThe factorial design experimental method used to investigate Cd exposure dose and exposure time.36 male New Zealand rabbits were divided into 12 groups,each group was three, taking CdCl2 and mercaptoethanol (ME) mixture respectively with 0,0.5,1.5,4.5 μmol/kg body weight by ear vein inject method,1 times/d,5d continuous, to detect blood cadmium, kidney cadmium, urine cadmium, urinep2-microglobulin respectively after exposure 21 d,35 d and 49 d, and to observe pathologic indicators and select the best conditions for a rabbit model of chronic cadmium poisoning by statistical analysis.2. The infusion therapy trials and sid-effect of GMDTC on chronic cadmium poisoning rabbit model60 male New Zealand rabbits were divided into 2 groups,one was blank control group with 12, another was chronic cadmium poisoning model group with 48. Taking CdCl2 and mercaptoethanol (ME) mixture with 1.5 μmol/kg body weight by ear vein inject method,1 times/d,5d continuous, observed 35 days. The control group (n= 4) and cadmium model group (n= 6) animals were randomly divided into three batches of 11 group according to the weight:1 week batch seted up blank control group, model control group, GMDTC (433 mg/kg) high dose groups, GMDTC (108 mg/kg) low dose group, EDTA-calcium (95 mg/kg) positive control group; 2 weeks batch seted up blank control group, model control group, GMDTC (433 mg/kg) high dose groups; 4 weeks batch seted up blank control group, model control group, GMDTC (433 mg/kg) high dose groups. All dosing by intravenous infusion,1 times/d, intravenous infusion rate was 30 drops/min, infusion time was about 3-4 h. Each one week as a course of treatment and interval was one day. Collected urine during 0-6 h and 7-24 h amount intravenous. Measured the trace elements of Cd, iron, calcium, zinc, copper, magnesium etc in blood, urine, kidney, liver, brain, lung and testicular, and got on pathological examination after the experiment.Results1. A factorial design trial of preparing chronic cadmium poisoning rabbit model①Urine P2-microglobulin was significantly increased in 35 days and 49 days of cadmium exposure (P<0.01);②The content of blood cadmium and organs cadmium was ascended order with the increased dose (P<0.01;③Kidney disease mainly interstitial nephritis, pyelonephritis, few animals had tubular necrosis; liver disease primary hepatocytes edema; testicular lesions mainly testicular atrophy in cadmium model control group animals.④Factorial design analysis results:With the increase of dose and time, kidney cadmium content showed a clear tendency to increase, and the dose played a major role in the experimental results. In this experimental condition, dose 1.5 μmol/kg,35 days was the best experimental conditions, that is rabbits exposed with Cd 1.5μmol/kg+ME 30 μmol/kg mixed solution by intravenously,1 times/d,5d continuous, observed 35 days, could successfully prepare chronic cadmium poisoning rabbit model.2. The infusion therapy trials and side effects of GMDTC on chronic cadmium poisoning rabbit model① Kidney cadmium content determination:Compared with the model group of the same treatment time, GMDTC treated one week, EDTA-calcium group, GMDTC low dose group, GMDTC high dose group kidney cadmium levels were significantly decreased, and the high-dose group kidney cadmium content decreased the most obvious, differences were significant (P<0.05), kidney cadmium drive ratio was 18.90%,41.42%,50.62% respectively; GMDTC treated two weeks, kidney cadmium drive was 77.11%; GMDTC treated four weeks, the kidney cadmium drive was 94.01%.(2)The amount of urine cadmium determination:Compared with the model group of the same treatment time, GMDTC treated one week, EDTA-calcium group, GMDTC low dose group, GMDTC high dose group dosing 0-6 h and 7-24 h, urinary cadmium content was significantly increased (P<0.01); GMDTC treated four weeks, GMDTC high dose group dosing 0-6 h and 7-24 h, urinary cadmium level was significantly increased (P<0.01).③Other organs cadmium content determination: Compared with the blank control group of the same treatment time, brain cadmium, liver cadmium, lung cadmium, testicular cadmium levels were significantly increased in model group and each treatment group (P<0.01); however brain cadmium, liver cadmium, lung cadmium, testicular cadmium between the treatment group and model group were no significant difference (P>0.05). ④Organ trace elements determination: GMDTC treated four weeks, compared with the model group of the same treatment time, renal Zn trace element were significantly decreased (P<0.05) in treatment group; compared with the blank control group of the same treatment time, renal Mg trace element significantly lower (P<0.05) in treatment group; compared with the blank control group of the same treatment time, kidney Ca level in model group was significantly higher trend (P<0.05); and compared with the blank control group of the same treatment time, brain Zn and brain Ca level in model group and treatment group were significantly decreased (P<0.01). ⑤sperm deformity and bone marrow micronucleus determination:no obvious toxicity.⑥The animal quantity of lesions and the degree of lesions more serious in model group and in GMDTC treatment group. Kidney disease was mainly interstitial nephritis, pyelonephritis, few animals developed renal tubular necrosis; liver disease primarily was liver cell edema, visible minority interstitial hepatitis and hepatic necrosis; testes main lesion was testicular atrophy.Conclusion1. Rabbits exposed the mixed solution of Cd 1.5 μmol/kg+ME 30 μmol/kg by intravenously,1 times/d,5d continuous, observed 35 days, could successfully prepare chronic cadmium poisoning rabbit model.2. Intravenous GMDTC could quickly clear kidney cadmium in chronic cadmium poisoning rabbit, dosing one week of kidney cadmium purge rate was 50%, better than the mice dosing one month by intraperitoneal injection, extend the delivery time could significantly improve the effect of drive cadmium, dosing 4 weeks could clear most of the kidney cadmium, kidney drive cadmium rate up to 94%.3. In the course of GMDTC treatment, the animals general state were good, no significant temperature changed, it had little effect on the content of Zn2+, Ca2+, Fe3+, Cu2+, Mg2+ trace elements, serum electrolytes and organ coefficient, sperm deformity and bone marrow micronucleus were not observed toxicity.4. GMDTC is expected to develop a safe, effective drug of drive cadmium.