Betaine downregulates microRNA 34a expression via a p53‐dependent manner in cisplatin‐induced nephrotoxicity in rats

Abstract Cisplatin‐induced nephrotoxicity limits its wide application as a chemotherapeutic drug. Betaine is a natural trimethylglycine compound involved in several biological reactions. In this study, the protective effect of betaine against cisplatin‐induced nephrotoxicity through modulating the expression of microRNA 34a (miRNA 34a), p53, apoptosis, and inflammation was investigated. Adult Wistar rats were divided into normal group (received vehicle); betaine group (received 250 mg betaine/kg BW/day via oral gavage from Day 1 to Day 25); cisplatin group (received a single intraperitoneal dose of cisplatin at 5 mg/kg BW on Day 21) and betaine + cisplatin group (received the same doses of betaine and cisplatin). The results demonstrated that the cisplatin group exhibited severe kidney tissue damage and an increase in blood creatinine and urea levels. Furthermore, the cisplatin group showed a significant upregulation of miRNA 34a and higher levels of phospho‐p53, caspase 3, cytochrome c, NF k B, and IL‐1β compared to the normal group. Remarkably, the betaine + cisplatin group showed significantly decreased blood creatinine and urea concentrations, decreased levels of miRNA 34a, phospho‐p53, caspase 3, cytochrome c, NF k B, and IL‐1β as well as improved kidney tissue integrity compared to the cisplatin group. In conclusion, cisplatin‐induced nephrotoxicity in rats was associated with upregulation of miRNA 34a expression, apoptosis, and inflammation in p53‐dependent manner. These effects were reversed by betaine administration that ultimately improved the kidney function and tissue integrity.