The effect and mechanism of astragaloside Ⅳ on lysophosphatidic acid-induced neurite retraction of N1E-115 cells / 国际中医中药杂志

Objective:To observe the effect of astragaloside Ⅳ on lysophosphatidic acid(LPA)- induced neurite retraction of N1E-115 cells and its potential mechanism.Methods:N1E-115 cells were divided into blank group, model group, the low, medium and high dose groups of astragaloside Ⅳ. The blank group and model group was not intervened by astragaloside; while the low, medium and high dose groups were treated with 20,40 and 80 μg/ml astragaloside Ⅳ for 24 h. Each group was cultured with serum-free medium for 12 h. The model group and astragaloside Ⅳ groups were intervened by 40 μmol/L LPA for 10 min. Each group was observed and photographed with the inverted microscope, and the number of neurites in N1E-115 cells was counted by Image J software. The fluorescence expression of recombinant ras homolog gene family member A (RhoA), rho associated coiledcoil protein kinase 2 (ROCK2), phospho-rho associated coiledcoil protein kinase 2 (p-ROCK2) and phospho-myosin light chain 2 (p-MLC2) proteins was detected by immunohistochemistry. Real-time fluorescent quantitative polymerase chain reaction was used to detect the mRNA expression levels of RhoA and ROCK2 ; the protein expression levels of RhoA, ROCK2, p-MLC2 and myosin light chain 2 (MLC2) were detected by Western blotting.Results:Compared with 20 μg/ml astragaloside Ⅳ group, the inhibition rate of neurite retraction in 40 and 80 μg/ml astragalosideⅣ groups increased ( P<0.05). Compared with model group, the average fluorescence intensity of RhoA, p-ROCK2, p-MLC2 in 20, 40, 80 μg/ml astragaloside Ⅳ groups and the ROCK2 average fluorescence intensity in 40 μg/ml astragaloside Ⅳ group were decreased ( P<0.05, P<0.01); the expression of RhoA mRNA (0.89±0.09, 0.41±0.01, 0.09±0.03 vs. 1.50±0.01) and ROCK2 mRNA (0.89±0.09, 0.14±0.01, 0.20±0.01 vs. 1.62±0.17) decreased in 20, 40, 80 μg/ml astragaloside Ⅳ groups ( P<0.05, P<0.01); the ROCK2 protein (0.75±0.06, 0.57±0.02, 0.66±0.01 vs. 1.08±0.02), p-MLC2 protein (1.72±0.03, 1.40±0.04, 1.29±0.03 vs. 2.19±0.11), MLC2 protein (1.13±0.02, 0.68±0.03, 0.75±0.03 vs. 1.60±0.03) in 20, 40, 80 μg/ml astragaloside Ⅳ groups and the RhoA protein (0.35±0.01, 0.40±0.03 vs. 0.57±0.08) in 20, 40 μg/ml astragaloside Ⅳ groups were decreased ( P<0.05, P<0.01). Conclusion:Astragaloside Ⅳ can prevent LPA-induced neurite retraction and promote damaged nerve regeneration. The mechanism may down-regulae the protein expression levels of RhoA, ROCK2, p-ROCK2, p-MLC2 and MLC2 in RhoA-ROCK2 signaling pathway, and inhibite nerve growth cone collapse.

Effect of butylphthalide on brain edema and the expression of phosphorylated myosin light chain in peri-infarct tissue in focal cerebral ischemic rats / 国际脑血管病杂志

Objective To investigate the effect of butylphthalide on brain edema and the expression of phosphorylated myosin light chain in peri-infarct tissue in focal cerebral ischemic rats.Methods A total of 212 adult male Sprague-Dawley rats were divided into a sham operation group (n =12),a cerebral ischemia group (n =100),and a butylphthalide group (n =100) (40 mg/kg,1/day,gavage) according to the random number table.Both the cerebral ischemia group and the butylphthalide group were redivided into 6 h,12 h,1 d,3 d,and 7 d groups (n =20 for each time point).A rat model of focal cerebral ischemic model was induced by photochemical method; 2,3,5-triphenyl tetrazolium chloride (TTC) staining was used to detect infarct volume (n =5); wet-dry weight method was used to detect the water content in brain tissue (n =5);immunohistochemistry (n =5) and Western blot (n =5) were used to detect the protein expression of periinfarct cortical p-MLC.Results TTC staining showed that no infarcts were observed in the sham operation group.The infarct volumes at each time points in the butylphthalide group were significantly less than those at the same time points in the cerebral ischemia group (all P ＜0.05).Wet-dry weight method showed that the water contents in brain tissue in the cerebral ischemia group and the butylphthalide group were significantly higher than that in the sham operation group (all P ＜ 0.05),but the water contents in brain tissue at each time points in the butylphthalide group was significantly lower than those at the same time points in the cerebral ischemia group (all P ＜ 0.05).Both immunohistochemistry and Western blot showed that the expressions of peri-infarct cortical p-MLC in both the cerebral ischemia group and the butylphthalide group were upregulated significantly compared to the sham operation group (all P＜ 0.05),but the expressions of peri-infarct cortical p-MLC at each time points in the butylphthalide group was significantly lower than those at the same time points in the cerebral ischemia group (all P＜ 0.05).Conclusions Butylphthalide can be up-regulated by reducing the expression of p-MLC caused by cerebral ischemia and reduce cerebral edema,and then reduce the infarct volume,and thus play a neuroprotective effect.

Staurosporine and cytochalasin D induce chondrogenesis by regulation of actin dynamics in different way

Actin cytoskeleton has been known to control and/or be associated with chondrogenesis. Staurosporine and cytochalasin D modulate actin cytoskeleton and affect chondrogenesis. However, the underlying mechanisms for actin dynamics regulation by these agents are not known well. In the present study, we investigate the effect of staurosporine and cytochalasin D on the actin dynamics as well as possible regulatory mechanisms of actin cytoskeleton modulation. Staurosporine and cytochalasin D have different effects on actin stress fibers in that staurosporine dissolved actin stress fibers while cytochalasin D disrupted them in both stress forming cells and stress fiber-formed cells. Increase in the G-/F-actin ratio either by dissolution or disruption of actin stress fiber is critical for the chondrogenic differentiation. Cytochalasin D reduced the phosphorylation of cofilin, whereas staurosporine showed little effect on cofilin phosphorylation. Either staurosporine or cytochalasin D had little effect on the phosphorylation of myosin light chain. These results suggest that staurosporine and cytochalasin D employ different mechanisms for the regulation of actin dynamics and provide evidence that removal of actin stress fibers is crucial for the chondrogenic differentiation.

Role and mechanism of phosphate myosin light chain in chronic allograft nephropathy of rats / 中华器官移植杂志

Objective To investigate the role and mechanism of phosphate myosin light chain (pMLC) in the rat kidney of chronic allograft nephropathy (CAN) model. Methods The left donor kidneys from Fisher (F344) rats were orthotopically transplanted into Lewis recipients. Meanwhile, the F344 rats and LEW rats with resection of the right kidney served as control groups. Animals were harvested respectively at the 4th, 8th and 12th week after transplantation. The creatinine clearance rate (CCr) was calculated by urine creatinine of 24-h urine. Blood samples were collected from rats for determination of serum creatinine. The expression of pMLC was detected by using Western blotting and immunohistochernistry, and that of integrin-linked kinase (ILK) by using immunohistochemistry. Results Mononuclear cells infiltration of allografts was markedly aggravated as compared to the controls. Allografts got severe interstitial fibrosis and tubular atrophy at 12th week after transplantation. The expression of pMILC and ILK was up-regulated in the kidney of CAN rats after transplantation, and increased more significantly as the time went on. The expression of pMILC was significantly correlated with 24-h urine protein excretion (r= 0. 273, P＜0. 05), serum creatinine levels (r = 0. 434, P＜0. 01 ), the number of tubulointerstitial infiltrated mononuclear cells (r = 0. 525, P＜0. 01 ), the number of smooth muscle cells (SMC) in vascular wall (r= 0. 676, P＜0. 01 ) and the extent of interstitial fibrosis (r= 0. 570, P＜0. 01 ).There was a significantly positive correlation between ILK and pMLC in CAN rats at the 4th week after transplantation (r= 0. 778, P＜0. 01 ). Conclusion pMLC might play an key role in CAN, and the over-expression of ILK might be involve in the pathogenesis of CAN.