Changes in gene expression and neuroinflammation in the hippocampus of rats with poststroke cognitive impairment

Poststroke cognitive impairment (PSCI) often occurs during the stroke recovery period and greatly increases the difficulty of rehabilitation. Activation of neuroinflammation and long-term changes in gene expression patterns in the hippocampus could be essential in the development of PSCI. Therefore, this study aimed to identify neuroinflammation and changes in gene expression patterns in the hippocampus in rats with PSCI. Rats underwent transient middle cerebral artery occlusion (tMCAO) or sham surgery. The infarct volume was measured on day 3 after surgery. The Morris water maze (MWM) test was used to assess cognitive function. Microglial activation and white matter (WM) lesions in the hippocampus were evaluated on day 28 after surgery. In addition, we compared differentially expressed genes (DEGs) in the hippocampus between tMCAO group rats and sham group rats by RNA sequencing. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) network analyses were conducted to investigate these DEGs. The results showed that the tMCAO group rats showed extensive infarction and cognitive dysfunction compared with the sham group rats. Microglial activation and WM damage were obvious in the hippocampus of tMCAO group rats. We found 43 DEGs by RNA sequencing: 29 genes with upregulated expression and 14 genes with downregulated expression. The GO analysis indicated that DEGs were mainly involved in cell proliferation and differentiation, cholesterol synthesis, and metabolism. The KEGG pathway analysis suggested that the DEGs were significantly enriched in intestinal immune network for IgA production and steroid biosynthesis. Acta2, Calb2, and Cxcl12 were notable in the PPI analysis. Our results suggest that microglial activation and WM damage are maintained in rats with PSCI. The mechanism may be related to the regulation of steroid biosynthesis, intestinal immunity, and potential key genes such as Acta2, Calb2, and Cxcl12 in the hippocampus.