Preconditioning exercise reduces brain damage of ischemic stroke in rats via PI3K-AKT pathway by bioinformatic analysis

Abstract

Ischemic stroke is one of the most vital causes of high neurological morbidity and mortality in the world. Preconditioning exercise is considered as the primary prevention of stroke to resistance to subsequent injury. We tried to research the underlying biological mechanisms of this exercise. Forty-two SD rats were randomly divided into three groups: middle cerebral artery occlusion (MCAO) group, exercise group with MCAO (EX + MCAO) group, and sham group, with 14 rats in each group. The EX + MCAO group underwent exercise preconditioning for 3 weeks before occlusion, and the other two groups were fed and exercised normally. After 3 weeks, MCAO model was made by thread plug method in the EX + MCAO group and MCAO group. After successful modeling, the Longa scale was used to evaluate the neurological impairment of rats at day 0, day 1, and day 2. The rats in each group were killed on the third day after modeling. TTC staining measured the infarct volume of each group. The morphology and apoptosis of cortical cells were observed by HE and Tunel staining. Three rats in each group underwent high-throughput sequencing. Bioinformatic analysis was used to find the deferentially expressed genes (DEGs) and predict the transcription factor binding sites (TFBS) of the next-generation sequencing results. Gene enrichment (GSEA) was used to analyze potential functional genes and their corresponding signaling pathways. The Longa scale showed EX + MCAO group had the neurological function better than the modeling group (P < 0.001). TTC staining showed that the infarct size of EX + MCAO group was less than MCAO group (P < 0.05). HE and Tunel staining showed that the cells in the EX + MCAO group and the sham group had normal morphology and fewer apoptotic cells than MCAO group. A new gene named 7994 was discovered and TFBS of this gene was predicted, which could interact with key genes such as Foxd3, Foxa2, NR4A2, SP1, CEBPA, and SOX10. GSEA showed that EX + MCAO group could promote and regulate angiogenesis and apoptosis through PI3K-AKT pathway. Preconditioning exercise could improve nerve function and reduce infarct size in rats. The underlying mechanism is to regulate the PI3K-AKT pathway through several key genes, promote cerebral angiogenesis, and reduce apoptosis.

Keywords: Bioinformatic analysis; High-throughput sequencing; Ischemic stroke; Preconditioning exercise.