Serum microRNA Profiling at an Early and Late Stages of Rotenone-Induced Parkinson’s Disease in Rats

This study investigates alterations in serum microRNA (miRNA) expression during the early (10-day) and late (terminal) stages of Parkinson’s disease (PD) in a rotenone-induced rat model. Rotenone, a mitochondrial complex I inhibitor, was administered to induce PD-like pathology by impairing ATP production. Blood serum samples were collected from control, early-stage PD (EPD), and late-stage PD (LPD) groups following treatment. Serum was processed for small RNA extraction and subjected to high-throughput sequencing using the Illumina platform with a single-end read length of 50 bp. Differential miRNA expression across stages was profiled to identify potential circulating biomarkers and gain insight into disease progression. To investigate circulating miRNA expression changes during the progression of Parkinson’s disease, we utilised a rotenone-induced rat model representing early and late stages of the disease. Adult male rats were randomly assigned to three groups: Control, Early Parkinson’s Disease (EPD, 10 days of rotenone treatment), and Late Parkinson’s Disease (LPD, terminal stage more than 40 days of prolonged rotenone exposure). Rotenone (2.0 mg/kg/day) was administered daily via intraperitoneal injection in male Wistar rats to induce dopaminergic neurodegeneration. Following the completion of treatment and behavioural validation of the disease model, blood samples were collected from all animals at their designated endpoints. Blood was allowed to clot at room temperature and then centrifuged to isolate serum. Serum samples from all groups were submitted to a commercial sequencing facility for small RNA sequencing. Library preparation was performed according to standard protocols for small RNA analysis. Sequencing was conducted using the Illumina platform, generating approximately 20 million raw reads per sample with a single-end read length of 50 base pairs.