[Protective effects of puerarin on lens epithelial cells in rat diabetic cataract]

The therapeutic effects of general and local applications of puerarin in the treatment of streptozotocin (STZ)-induced rat diabetic model were compared.

Experimental research. We equally divided normal Sprague-Dawley (SD) rats into a STZ group, a peritoneal injection group, a peribulbar injection group and a control group. STZ, peritoneal injection and peribulbar injection groups were first treated with STZ. Subsequently, the STZ group was injected with normal saline intraperitoneally, while in the later two groups puerarin was injected through peritoneal and peribular routes, respectively. Control group only received peritoneal injection of saline. The morphology of lens epithelial cells (LEC) and their subcellular structure were examined by bright-field microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) 20, 40 and 60 days after the injection. Nitrogen oxide (NO) and nitric oxide synthase (NOS) were measured by biochemistry methods. Finally, inducible nitric oxide synthase (iNOS) protein and mRNA levels were monitored by Western blot and RT-PCR, respectively. Data was processed with two factorial experiment analysis of variance.

Twenty to sixty days after the injection, marked or complete lens opacities appeared in the STZ group, whereas only slight opacities appeared in the lens in peritoneal and peribulbar puerarin groups and the lens in the control group remained clear. At the 20th, 40th and 60th day after the injection, optical microscope detected pathological changes of LEC in the STZ group. The cell volume was decreased with a dense nucleus and many bubbles appeared around the equator area. Under TEM, enlargement of cell gap, vacuoles in the cytoplasm, swelling of mitochondria and unclear structure of rough endoplasmic reticulum appeared in the LEC of the STZ group. Part of the nucleus was in karyopyknosis and peripheral nucleus gap was enlargement. Under SEM, normal fiber conjunction structure of the lens disappeared, fibers were swelling, part of fiber membranes were discontinuous, detached, and accumulated in certain areas. Mild lens opacities detected by bright-field microscope were developed in peritoneal and peribulbar puerarin injection groups. Nucleus and fibers in the lens cells of both groups appeared to be normal, with minor swelling of mitochondria, minor enlargement of endoplasmic reticulum and slight increase of intracellular space. NO, NOS and iNOS protein and mRNA of the lens were increased and up-regulated in STZ group. In the other two groups only minor changes were present and the changes were significantly less than that of the STZ group but greater than that in the control group.

Peritoneal and peribulbar injection of puerarin have similar therapeutic effects in the treatment of rat diabetic cataract.