Possible Protective Effects of Two Different Doses of Cyanocobalamin Against Methotrexate Nephrotoxicity Model in Rats

Nephrotoxicity is defined as rapid deterioration in kidney functions. It arises from direct exposure to drugs or their metabolites. Methotrexate is a famous chemotherapeutic drug with anti-inflammatory and immunosuppressive properties. A high-dose methotrexate-induced renal dysfunction can be life threatening. Cyanocobalamin, one of the forms of vitamin B12, acts as a coenzyme in the conversion of homocysteine to methionine in the cytosol, and the conversion of methylmalonyl-CoA to succinyl-CoA in the mitochondrion. The study was designed to investigate the possible protective role of intraperitoneal cyanocobalamin administered in 2 different doses, against rat model of nephrotoxicity induced by methotrexate. Rats utilized in this study were randomized into 4 groups (ten rats per each group); Group 1- (Control) rats intraperitoneally injected with 0.5ml normal saline once daily for 7 consecutive days. Group 2- Rats intraperitoneally injected with 0.5ml normal saline once daily for 7 consecutive days; and at day 2, a single intraperitoneal dose of methotrexate (20mg/kg) is to be injected. Group 3- Rats intraperitoneally injected with a 0.5mg/kg cyanocobalamin once daily for 7 consecutive days, and at day 2, a single intraperitoneal dose of methotrexate (20mg/kg). Group 4- Rats intraperitoneally injected with a 2mg/kg cyanocobalamin once daily for 7 consecutive days, and at day 2, a single intraperitoneal dose of methotrexate (20mg/kg). Co-administration of cyanocobalamin at doses cyanocobalamin 0.5mg/kg and 2mg/kg with methotrexate showed significant-reduction- (P<0.05) in malondialdehyde, significant elevation (P<0.05)-in the glutathione level, significant upregulation in renal Nrf2 expression and significant down regulation in renal keap1 expression each compared to corresponding levels in methotrexate-only treated group. In conclusion this study demonstrated that co-administration of cyanocobalamin at two different doses with MTX resulted in attenuation of its nephrotoxicity by the utilization of selected parameters.