Therapeutic Potential Of Cardiotoxin From Naja Naja Atra Venom On Adriamycin Nephropathy Rats And Effects On Expression Of Podocin In Podocytes

Objective: To observe the effects of cardiotoxin from Naja naja atra venom on proteinuria, biological parameters and podocin in adriamycin-induced nephropathy rats.Methods: The 35 Wistar rats were randomly divided into five groups. The model group and the treatment group were injected with adriamycin(ADR; 6 mg/kg body weight) via the tail vein to induce adriamycin nephropathy model, while the normal group were injected with saline as a control group. Then the treatment groups were orally administrated cardiotoxin at doses of 45μg/kg, 90μg/kg, and 180μg/kg until the end of the protocol. The control group and model group were daily intragastric injection of distilled water. All rats were weighed and placed in metabolic cages for 24 hours to collect urine, for determination of proteinuria, once a week. After 6 weeks, the rats were sacrificed to determine serum profiles relevant to adriamycin neohropathy, including albumin, globulin, total cholesterol, triglyceride, phosphorus, blood urea nitrogen, and serum creatinine. Kidney histology was examined with hematoxylin and eosin, periodic acid-Schif, and Masson’s trichrome staining. The levels of kidney podocin were analyzed by Western blot analysis and immunofluorescence.Results: Compared with the model group, urinary protein excretion of the treatment groups(45μg/kg and 90μg/kg) were significantly reduced after treatment for six weeks( 625.94±75.12mg/24 h vs 574.11± 92.41 mg/24h; 625.94±75.12mg/24 h vs 553.27±138.02mg/24h), especially in the first three weeks(P <0.05). Cardiotoxin significantly decreased the kidney coefficients at doses of 45μg/kg, 90μg/kg, and 180μg/kg, respectively( P<0.001, P<0.01,and P<0.001). Cardiotoxin at a dose of 180μg/kg, a slight increase in serum albumin(17.43±2.25g/L versus 18.49±2.15g/L), and a significant decrease in serum globulin(102.17±27.14 g/L versus 64.01±26.58 g/L, P<0.05)were detected. The levels of total cholesterol(TC)were significantly decreased after administration of 180μg/kg cardiotoxin for 6 weeks(15.05±0.93 versus 11.22±3.00 mmol/L,P<0.01).There was no significant difference in triglyceride(TG) levels after treatment of 180μg/kg cardiotoxin even though there was a drop from35.32±11.27 to 21.70±12.09 mmol/L. The levels of phosphorus(P) were markedly decreased(2.95±0.20 versus 2.57±0.28 mmol/L; P< 0.01) after administration of 180μg/kg cardiotoxin for 6 weeks. However, after treatment with 45μg/kg, 90μg/kg, 180μg/kg of cardiotoxin for 6 weeks, BUN was significantly decreased(10.30±0.84 mmol/L versus 8.21±1.53mmol/L,P<0.01;10.30±0.84 mmol/L versus 8.78±1.74mmol/L,P<0.05; 10.30±0.84 mmol/L versus 8.42±1.39mmol/L,P<0.05)and the level of SCr was slightly decreased(49.47±8.69 umol/L vs 46.36±3.72 umol/L,49.47±8.69 umol/L vs 44.94±7.18 umol/L,49.47±8.69 umol/L vs 47.47±4.76 umol/L). The decrease in the number of glomeruli, occurrence of fatty degeneration, tubular necrosis, inflammatory cell infiltration, abundant leaked protein in the tubular lumen, thick glomerular basement membrane and tubulointerstitial collagen proliferation were detected in the kidney histology of model group. Those changes were mitigated and improved after administration of cardiotoxin at doses of 45, 90, and 180μg/kg for 6 weeks. After treatment with cardiotoxin for 6 weeks, podocin protein expression was slightly increased compared with the model group which were detected by western blot analysis and immunofluorescence.Conclusion:1. Intragastric administration of cardiotoxin can reduce loss of body weight, signficantly ameliorate kidney hypertrophy and reduce proteinuria of adriamycin nephropathy rat model in the early stages.2. Cardiotoxin can significantly reduced the loss of serum albumin, inhibited the increase in globulin, ameliorated hyperlipidaemia and regulated the balance of serum electrolytes.3. Cardiotoxin significantly ameliorated the renal function disorder of adriamycin nephropathy rat model.4. Cardiotoxin can reduce the decrease in the number of glomeruli and occurrence of fatty degeneration. Cardiotoxin also can mitigate tubular necrosis, inflammatory cell infiltration and abundant leaked protein in the tubular lumen. Cardiotoxin can improve the thick glomerular basement membrane and tubulointerstitial collagen proliferation.5. Cardiotoxin can partially restore podocin expression levels in adriamycin nephropathy rat model.