ABSTRACT
Chronic obstructive pulmonary disease (COPD) is an important healthcare problem worldwide. Often, glucocorticoid (GC) resistance develops during COPD treatment. As a classic hypoglycemic drug, metformin (MET) can be used as a treatment strategy for COPD due to its anti-inflammatory and antioxidant effects, but its specific mechanism of action is not known. We aimed to clarify the role of MET on COPD and cigarette smoke extract (CSE)-induced GC resistance. Through establishment of a COPD model in rats, we found that MET could improve lung function, reduce pathological injury, as well as reduce the level of inflammation and oxidative stress in COPD, and upregulate expression of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), multidrug resistance protein 1 (MRP1), and histone deacetylase 2 (HDAC2). By establishing a model of GC resistance in human bronchial epithelial cells stimulated by CSE, we found that MET reduced secretion of interleukin-8, and could upregulate expression of Nrf2, HO-1, MRP1, and HDAC2. MET could also increase the inhibition of MRP1 efflux by MK571 significantly, and increase expression of HDAC2 mRNA and protein. In conclusion, MET may upregulate MRP1 expression by activating the Nrf2/HO-1 signaling pathway, and then regulate expression of HDAC2 protein to reduce GC resistance.
ABSTRACT
BACKGROUND:During the progress of focal cerebral ischemia-reperfusion in rat with transient suture occlusion, bleeding combating and the line being plugged into the cerebral middle artery smoothly are important for successful modeling and research focus. OBJECTIVE:To improve Longa suture occlusion method for focal cerebral ischemia reperfusion model in Sprague-Dawley rats in order to establish a simple surgical procedure with low rate of intraoperative bleeding and high rate of successful models. METHODS:The two ends of the external carotid artery were clipped with electric knife, in addition to ligation of surgery lines intraoperatively;with the help of pincett, a fishing line was plugged into the carotid artery along the anteriomedialis artery wal (the direction of the internal carotid artery from the pterygopalatine arterial bifurcation). Postoperative behavior scores in rats, infarct volume calculation and histopathological evaluation under optical microscope were done. RESULTS AND CONCLUSION:Transverse sections of the external carotid artery were changed from a“O” shape to a“-”shape after being clipped with electric knife. Subsequently, line nodes were not easy to fal off any more, effectively preventing intraoperative bleeding. With the power of pincett, the rate of plugging the fishing line into artery was significantly increased. Rat’s neurological score and infarct volumes were significantly increased, and brain tissue pathological injury worsened. The modified suture occlusion method for focal cerebral ischemia reperfusion models effectively prevented line nodes off, successful y increased the rate of suture occlusion and models in Sprague-Dawley rats were developed successful y.