Streptozotocin (STZ) (50 mg/kg) was successfully used to induce diabetes in male Sprague-Dawley rats, which were randomly assigned to a group taking SDMM capsules ("diabetic+SDMM") or a control group ("diabetic"), and the normal group (n=10/group). The diabetic+SDMM
capsule group received 1.89g/kg/d of SDMM
capsule by gavage, whereas the other groups received the same amount of distilled water. After 12-weeks of gavage, the retina was removed from all rats for histopathological analysis, and
miRNA sequencing experiments were carried out to identify the differential expression of
miRNAs. These results were then confirmed by quantitative real-time polymerase chain reaction (qRT-PCR).
Results: SDMM capsules improved
retinal morphology, restored the number of cells in the
ganglion cell layer (p<0.0001) and reduced apoptosis in all
retinal layers (p values in the outer nuclear layers, inner nuclear layers and
ganglion cell layers 0.0001, 0.0147, 0.0034, respectively). In addition,
miRNA expression was changed in rats taking SDMM capsules. Compared with the diabetic group, six
miRNAs were up-regulated and four
miRNAs were down-regulated in the diabetic+SDMM
capsule group. The qRT-PCR validation results showed that the expression levels of miR-450b-5p, miR-1249 and miR-155-5p were consistent with the trend of
miRNA sequencing results, and were all up-regulated after SDMM
capsule treatment. Target gene prediction and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed
miRNAs showed that these pathways were mainly concentrated in the focal adhesions and PI3K/Akt, MAPK, and neural factor signaling pathways.
Conclusion: