ABSTRACT
Objective:To observe whether endoplasmic reticulum stress and NOD-like receptor protein 3 (NLRP3) inflammasome activation were involved in severe heat stroke induced intestinal mucosal injury and to investigate the potential protective effect of the endoplasmic reticulum stress inhibitor 4-phenylbutyric acid (4-PBA).Methods:Thirty male BALB/c mice were randomly (random number) assigned to 3 groups: the control group, heat stroke group (HS), and 4-PBA pretreatment group (4-PBA+HS, 4-PBA 120 mg/kg, intraperitoneal injection). Mice in the control group were placed at room temperature, while mice in the HS group and 4-PBA+HS group were placed in a prewarmed chamber [temperature (35.5±0.5) °C, humidity (60.0±5.0)%]. A rectal temperature (Tc) that reached 42 °C was considered to indicate severe heat stroke. The concentrations of malondialdehyde (MDA) and superoxide dismutase (SOD) in intestinal homogenate were analyzed by a colorimetric method, serum interleukin-1β (IL-1β) and interleukin-18 (IL-18) were assessed by ELISA, intestinal histopathology was evaluated by hematoxylin and eosin (HE) staining, intestinal ultrastructure was observed by electron microscopy, and the protein expression of GRP78, CHOP, NLRP3 and cleaved caspase-1 were analyzed by Western blot. Data were statistically analyzed by ANOVA test and LSD- t multiple comparison test if homogeneous variance, or analyzed by Welch test and Dunnett's T3 multiple comparison test if heterogeneous variance. Results:The concentration of MDA in the HS group was increased ( t=14.243, P<0.01), while SOD was decreased compared with that in the control group ( t=7.781, P<0.01), and the concentrations of serum IL-1β and IL-18 were significantly elevated ( t=12.664, P<0.01; t=16.240, P<0.01). Under light microscopy, extensive destruction of small intestinal villi and inflammatory cell infiltration were observed in the intestines of mice with severe heat stroke. Transmission electron microscopy showed that endoplasmic reticulum structures were significantly expanded, and mitochondria were vacuolated in the intestines of mice with severe heat stroke. Compared with those in the control group, the protein expression levels of GRP78, CHOP, NLRP3 and cleaved caspase-1 in the small intestine were elevated in the HS group ( t=14.824, P <0.01; t=12.667, P<0.01; t=9.298, P<0.01; and t=6.588, P=0.001). Compared with those in the HS group, mice in the 4-PBA pretreatment group exhibited reduced concentrations of MDA ( t=9.167, P<0.01), increased SOD ( t=6.077, P<0.01) , and reduced serum IL-1β and IL-18 levels ( t=4.889, P= 0.001; t=5.693, P<0.01). In addition, 4-PBA pretreatment significantly alleviated the pathological disruption and ultrastructural damage to small intestine tissues. Moreover, 4-PBA pretreatment reduced GRP78, CHOP , NLRP3 and cleaved caspase-1 protein expression ( t=9.080, P<0.01; t=7.152, P<0.01; t=4.249, P=0.005; t=3.650, P=0.011). Conclusions:Endoplasmic reticulum stress and NLRP3 inflammasome are involved in intestinal mucosal injury induced by severe heat stroke. 4-PBA plays a protective role by alleviating endoplasmic reticulum stress and NLRP3 inflammasome activation.
ABSTRACT
Aim To explore the role of endoplasmic reticulum stress(ERS)signaling pathway in high fat-induced cell apoptosis in human umbilical vein endo-thelial cells(HUVECs). Methods HUVECs were ex-posed to different concentrations of palmitic acid(0. 1, 0. 2,0. 4,0. 8 mmol·L - 1 )for 24 h and different time points of 0. 4 mmol·L - 1 palmitic acid(0,12, 24,48 h). Cell viability was measured by cell count-ing kit(CCK-8),and the protein expressions of ERS signaling pathway protein such as GRP78,CHOP, PERK,IRE1,ATF6 were determined by Western blot. The level of intracellular apoptosis was detected by immunofluorescence. Results HUVECs exposed to palmitic acid at 0. 4 mmol·L - 1 for 24 h showed a de-crease in their viability and an increase in the expres-sion of ERS signaling pathway proteins (GRP78, CHOP,PERK,IRE1,ATF6)(P < 0. 05);cell ap-optotic levels significantly increased(P < 0. 05). The intracellular apoptosis levels in the vascular endothelial cells of ERS signaling pathway inhibitor 4-phenylbutyr-ic acid (4-PBA,10 mmol · L - 1 )were significantly lower than those of the PA group(P < 0. 05). Conclu-sion Activated ERS signaling pathway might play an important role in the treatment of high fat-induced cell apoptosis in vascular endothelial cells.
ABSTRACT
Objective To explore the effects of 4-phenylbutyric acid(PBA) on cognitive dysfunction after chronic cerebral hypoperfusion and underlying mechanisms.Methods 62 male Sprague Dawley rats in clean degree were divided into sham group(n=14),chronic cerebral ischemia group(bilateral carotid arteries occlusion,2VO group,n=24),and chronic cerebral ischemia with PBA treatment(2VO+PBA group,n=24).The chronic cerebral ischemia models were produced by the occlusion of bilateral common caroid artery for 1 month.During the hypoperfusion,the rats were injected intraperitoneally with 11.25 mg · ml-1 PBA(90 mg · kg-1 · d-1) or equal volume of saline once a day for 3 days followed by every other day for 27 days.Learning and memory abilities were tested by Morris water maze and novel object recognition test.The expression and distribution of NR2A in hippocampus were examined by Western blot and immunohistochemistry.Results Morris water maze test showed that the 2VO group had significantly longer latent time than sham group in searching platform (P＜0.01) (from 2nd day to 7th day latency time),and the 2VO+PBA group had dramatically shorter latent time than 2VO group (2nd,5th,6th,7th (P＜0.01),3rd(P＜0.05)).Then the rats' memory test showed that 2VO group spent markedly longer time than sham group to reach the location of the former platform(P＜0.01),but the 2VO+PBA group spent dramatically shorter latent time than 2VO group (P＜0.01).The novel object recognition test showed the exploration ratio and discrimination index of novel object in 2VO group were noticeably smaller than that in sham group (P＜0.01),but the exploration ratio and discrimination index of novel object in 2VO+PBA group were noticeably higher than that in 2VO group (P＜0.01).The Western blot data showed that the level of NR2A in 2VO group was significantly lower than that in sham group (P＜0.01),but the level of NR2A in 2VO+PBA group was significantly higher than that in 2VO group (P＜0.05).The level of NR2B in hippocampus of 2VO group had no significant difference with sham group and 2VO+PBA group (P＞0.05).Immunohistochemistry data was consistent with the data of Western blot for NR2A level and distribution.The ratio of p-CREB/total CREB in 2VO group(0.62±0.04) was remarkably lower than that in sham group(1.00±0.07),but the ratio of p-CREB/total CREB in 2VO+PBA group(0.97±0.07) was remarkably higher than that in 2VO group(P＜0.01).Conclusion NR2A reduction is associated with chronic cerebral hypoperfusion-induced cognitive impairment,which is rescued by the PBA treatment.It suggests that PBA may have a therapeutic effect on preventing chronic cerebral hypoperfusion-induced cognitive impairment.
ABSTRACT
Objective To study the role of endoplasmic reticulum stress in phenotypic change of cultured human glomerular mesangial cells induced by high glucose.Methods Cultured human glomeruar mesangial cells were divided into three groups: control group,high glucose group and high glucose+ 4-phenylbutyric acid (4-PBA) group.Cell number of proliferation was assessed by MTT assay.Cell cycle was measured by flow cytometric analysis.Expression of α-SMA was assessed by immunohistochemistry and was observed by laser scanning confocal microscope.Involved mRNA and protein expression were measured by real-time PCR and Western blotting.Results (1)Cell number of proliferation and S transition proportion in high glucose group significantly increased than that in control group (P ＜ 0.05).High glucose could induce α-SMA expression significantly (P＜0.05).4-PBA could significantly inhibit human glomerular mesangial cells proliferation (P＜0.05),S transition arrest (P＜0.05) and expression of α-SMA (P＜0.05) induced by high glucose.(2) Compared with control group,high glucose could significantly increase the expression of glucose-regulated protein78(Grp78 ) mRNA and protein (P＜ 0.05),which could be inhibited by 4-PBA treatment (P＜0.05).(3)High glucose could induce the mRNA and protein expression of TGF-β1 and FN significantly,which could be inhibited by 4-PBA treatment (P＜0.05).Conclusion Endoplasmic reticulum stress plays an important role in phenotypic change of cultured human glomerular mesangial cells induced by high glucose.
ABSTRACT
Objective To investigate the effect of 4-phenylbutyric acid(4-PBA)on the renal pathogenesis of rats with streptozotocin-induced diabetes and its mechanism. Methods Fifty-four male SD rats were randomly divided into three groups:normal control group(NC group,n=18),diabetic nephropathy group(DN group,n=18),diabetic nephropathy plus 4-PBA treatment group(4-PBA group,n=18).At the end of 4,8 and 12 weeks,index of kidney weight/body weight ratio(KI)were measured and calculated.Serum creatinine (Scr),blood urea nitrogen(BUN),urinary MDA levels,urinary SOD activity,and 24 hour urinary protein excretion ram(UAER)were detected by HITACHI automatically.Morphology of kidney wag examined by special staining of periodic acid-schitt (PAS).The p47phox and nitrotyrosine (NT) expression in kidney were determined by real-time fluorescence PCR and Western blotting. Results Compared with the NC group, the DN group rats showed a significant increase of KI(P＜0.05), UAER(mg/24 h) (4.92±0.70 vs 0.26±0.07, 5.29±0.83 vs 0.28±0.08, 5.54±0.81 vs 0.29±0.04,respectively, P＜0.05]for indicated time, mesangial cells proliferation and mesangial matrix expansion at 12 week. However,4-PBA treatment could significantly inhibit the increase of KI (P＜0.05), decrease UAER (mg/24 h) (3.71±0.37, 3.47±0.36, 3.28±0.40, respectively, P＜0.05]for indicated time, and prevent the glomeruler pathological alteration induced by diabetes. Moreover, the mRNA expression of p47phox in the kidney of DN group was 154.72%, 148.60% and 91.95% more than that of NC group (all P＜0.05) for indicated time. The protein expression of p47phox was 118.00%, 140.10% and 177.82% more than that of NC group (all P＜0.05), and the protein expression of NT was 45.29%,59.13% and 89.28% more than that of NC group (all P＜0.05). In addition, urinary MDA levels in DN group were 2.05-, 2.26- and 2.43- folds of NC group, and urinary SOD activities were decreased by 64.78%, 71.29% and 79.32% of NC group. Compared with the DN group, the mRNA and protein expression of p47phox, and protein expression of NT in 4-PBA group were decreased markedly (all P＜0.05) at the end of 8 and 12 weeks. The urinary MDA level was decreased, and the urinary SOD activity was increased significantly in rats with diabetes after 4-PBA treatment for indicated time (all P＜0.05). Conclusion 4-PBA treatment can significantly inhibit the renal pathogenesis of rats with diabetes through inhibition of oxidative stress.