Betulinic acid protects mice from cadmium chloride-induced toxicity by inhibiting cadmium-induced apoptosis in kidney and liver

Cadmium exposure is closely associated with a variety of diseases including cancers and the accumulation of cadmium has been long recognized as a public health problem. It is therefore of high importance to find methods to reduce cadmium accumulation in the human body. Herein, we report that administration of betulinic acid (BA) protects mice from cadmium chloride (CdCl2)-induced toxicity by inhibiting cadmium-induced apoptosis in both kidney and liver. Mice were given oral doses of 3 mg/kg, 10 mg/kg and 30 mg/kg of BA daily for ten consecutive days, and were injected with one dose of 1 mg/kg CdCl2 after one hour of BA administration every day. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and blood urea nitrogen (BUN) were assessed by ELISA. Residual cadmium was determined by atomic absorption analysis. Protein expression was evaluated by western blotting. Pretreatment with BA significantly reduced residual cadmium levels in the liver, kidney and testis, increased the cadmium output in urine, and reduced tissue damage induced by CdCl2. Moreover, BA prevented body weight loss by CdCl2 in a dose dependent manner. Furthermore, BA treatment increased the expression levels of B-cell lymphoma 2 (Bcl-2), decreased Bcl-2-associated X (Bax), and inhibited the levels of active caspase-3. Importantly, BA within a dose of 30 mg/kg did not induce any signs of toxicity, and protected mice from the toxicity induced by CdCl2 in a dose-dependent manner. Our findings suggest that BA inhibits CdCl2 induced apoptosis in the kidney and liver, and BA may be an effective agent for the prevention and treatment of cadmium-induced diseases in humans.