AIMTo evaluate the roles of puerarin in alleviating the STZ-induced lung injury.

METHODSDM model was established by streptozotocin (STZ) intraperitoneal injection to study the injury mechanisms of the lung. SD rats were divided randomly into control group (C group), diabetes group (DM group), diabetes + puerarin group (DM + Pur group). The blood glucose and weight were observed and recorded before and the 20 th, 40 th, 60 thd after administration of saline, STS, STZ+ Pur. Contents of NO and malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were measured in lung tissues. Light microscope (LM), transmission electron microscope (TEM) and immunohistochemical analysis were also used.

RESULTS(1) Compared with control group, the contents of NO and MDA were increased significantly (P < 0.01), while the activity of SOD reduced (P < 0.05). Compared with DM group, treatment with puerarin inhibited the increase of NO level (P < 0.01), and MDA content began to decline from 40 days after the model was established (P < 0.01), and inhibited the decrease of SOD activity induced by DM (P < 0.01). (2) LM and TEM results showed that alveolar and capillary basement membrane became thick, the number of tiny villus decreased markedly, the quantity of osmiophilic multilamellar body reduced remarkably, hyperplasia was shown in collgen fibre. Puerarin could alleviate above injuries induced by DM. (3) Immunohistochemical staining results showed that mild brown positive stain of NT could be seen in protoplasm of lung tissues. STZ administration induced the expression of NT in the protoplasm of cells, and led to stronger positive signals of NT than that of control group. Treatment with puerarin weakened the positive stain of NT.

CONCLUSION(1) DM induced by STZ leads to a significant and sustained increase in blood glucose and obvious lung injury, which may be associated with the overproduction of free radicals. (2) The pathway of NO/ONOO- is one of the injury mechanisms of the lung tissues cells. (3) Puerarin suppresses the expression of NT and elevates the activity of SOD. Thereby, resulting in the reduces of the production of free radicals, which may be one of the mechanisms of its anti-oxidative-injuries.