SIRT1 was Lowly Expressed in Rat Model of STZ
In order to study the effects of CMS on DR, the STZ rat model was
established by intraperitoneal injection of STZ and the rats were
divided into sham, STZ and CMS + STZ groups. Retinal tissues were
collected and observed after HE staining, which presented that the
vascular intima of retinal tissues in sham-operated rats consisted of a
layer of intact and continuous endothelial cells without hyperplasia.
Compared with the sham-operated rats, the rats injected with STZ
exhibited obvious edema, capillary wall thickening, endothelial cell
proliferation and fibrous tissue proliferation, which were partially
rescued by CMS in a dose-dependent manner (Figure 1A). After that, the
ultrastructure of retinas was observed under TEM, which showed that
compared with sham-operated rats, the retinal capillary endothelial
cells in rats treated with STZ were markedly swollen, the cell body
became round and protruded into the lumen with swelled and vacuolated
mitochondria as well as thickened basement membrane thickened, which
were partially blocked by treatment of CMS in a dose-dependent manner
(Figure 1B). In addition, the results of RT-qPCR and western blot
analysis showed that compared with sham-operated rats, the expression of
SIRT1 was notably decreased in rats treated with STZ, which was rescued
by CMS in a dose-dependent manner (Figure 1C - D). Therefore the
expression of SIRT1 was significantly inhibited in STZ rats, and CMS was
able to enhance the expression of SIRT1 in STZ rats.