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Objective To observe the oxidative stress, integrity of lysosome and apoptosis of intestinal epithelial cells 6 (IEC-6) after heat stress, and explore the pathogenesis of intestinal damage caused by heat stress.Methods In the heat stress groups,the cells were incubated at 43℃ for 1 hour, then, further incubated at 37℃ and 5% CO2 for 0, 1, 3, 6 and 12 hours respectively; in the medicine intervention group, the cells were pretreated with the medicine 1h before heat stress; while in control group, the cells were incubated at 37℃ and 5% CO2. The amount of reactive oxygen species (ROS) was assayed with 2', 7'-dichlorofluorescin diacetate (DCFH-DA) and dihydroethidium (DHE) staining. The stability of lysosome membrane was checked by AO staining. Apoptosis was analyzed by flow cytometry using annexinⅤ-FITC/PI staining, CCK-8 assay was used to assess cellular viability.Results Compared with control group, cell viability decreased and apoptosis increased at 1 h after heat stress, which was the most obvious at 12h after rewarming (P<0.05). While ROS and pale cells increased immediately after heat stress and the increase become the most obvious (P<0.05). The cell viability in E-64 pretreatment group was significantly improved such as apoptosis reduction, compared with heat stress group (P<0.05).Conclusion Heat stress could induce robust increase of ROS, which mediates lysosome damage and results in cell apoptosis, thus suggesting that ROS-lysosome pathway may play an important role in intestinal injury in heat stress.
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Objective To explore the protective effect of propofol on endothelial cells during heat stress and its protective effect to mitochondra. Methods Heat stress model of human umbilical vein endothelial cell was established when cells were incubated at 43℃ for 2h, then further incubted at 37℃, 5%CO2 for 6h. The experimental group was subdivided into six groups, including 37℃ group, 37℃ plus intralipid group (negative control group), 37℃ plus propofol group, 43℃ plus propofol group, 43℃ plus intralipid group, H2O2 plus propofol group (positive control group); Pretreated with 50μmol/L propofol, 0.2ml intralipid or 25μmol/L H2O2 before heat stress at 43℃, while the cells in the control group were incubated at 37℃. Cell viability was tested by CCK-8. ROS, mitochondrial membrane potential and the changes in mitochondrial permeability transition pore were determined by flow cytometry. The level of ATP was detected by fluorescein-luciferase. The changes of caspase-9 and caspase-3 were analyzed by Caspase Activity Assay Kit. Results HUVESs cell viability and damage of mitochondra were significantly decreased after heat stress. Compared with 43℃ heat stress group, pretreatment with propofol induced the recovery of cell viability and the ROS levels were significantly decreased in HUVEC cells (P<0.05). Meanwhile, the number of cells representing the decrease of mitochondrial membrane potential (the proportion of JC-1 monomer) was significantly decreased (P<0.05) by propofol. The average fluorescence intensity of calcein which representing the MPTP changes and intracellular ATP content was significantly increased (P<0.05). In addition, the activation of mitochondrial apoptotic pathway mediated by caspase-9/3 was also inhibited. Conclusions Propofol have anti-oxidative, anti-apoptosis and mitochondria protective effect against endothelial cell injury during heat stress.
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Objective To investigate the effect of gradient heat stress on phagocytosis of hepatic Kupffer cells (KCs) in vitro in rats. Methods Rat Kupffer cells were isolated in vitro and the temperature for gradient heat stress was set at 37, 39, 41 and 43℃. After thermal stimulation, cell injury was detected by PI and Hochest33342 staining. CCK-8 assay was used to investigate difference in cellular proliferation rate over 24h between the groups. Flow cytometry was used to investigate the influence of heat stress on the phagocytosis of KCs. Results Compared to the normal control group, cells in each heat stress group exhibited varying degrees of damage, especially cells in 43℃ group. The ratio of damage cells increased with the increase of heat stress severity (P<0.05). Proliferation assay indicated that the proliferation rate of cells in each heat stress group was significantly decreased in comparison with normal control group 6h after heat stress (P<0.05). After 12h recovery, decrease in proliferation rate was observed only in 43℃ group (P<0.001), and no difference in the rate of proliferation could be observed between the heat stress groups and normal control group after 24h recovery. Flow cytometry showed, that the phagocytosis of KCs decreased in heat stress groups compared with control group, especially in 43℃ group (P<0.05). This phenomenon disappeared after 24h recovery. Conclusion Heat stress can inhibit the phagocytosis of rat liver KCs through its cytotoxic effect on KCs, and subsequently inhibits its proliferative ability. Further investigation of the effect of heat stress on KCs may help understand the pathogenesis of heat stress.
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Objective To investigate the role of oxidative stress in acute liver injury in a heat stroke model of conscious rats,and to explore its underlying mechanism.Methods Thirty-two rats were randomly (by using a random number table) assigned into a sham-heated control group (Sham group,n=8),a sham-heated group treated with NAC (Sham-NAC group,n=8),a heat stroke group (HS group,n=8) and a heat stoke group treated with NAC (HS-NAC,n=8).Rats were prepared with pre-warm chamber to initiate heat stoke.The change of rectum temperature (Tr),heart rate (HR) and systolic blood pressure (SBP) were monitored,and the time point of HS onset was recorded.Rats were sacrificed 12h after HS onset.ALT,serum TBIL,IL-6,IL-1β,TNF-α,MDA,T-SOD and GSH in the liver homogenates were measured.Liver tissues were harvested for determining the concentration of reactive oxygen species (ROS),neutrophil infiltration and the histological changes.Results During HS onset,no significant differences were observed in Tr,HR,SBP and heat exposure time between HS group and HS-NAC group (P＞0.05).However,the survival time was significantly longer in HS-NAC group than in HS group (P=0.039).12 hours after HS onset,the concentrations of ROS and MDA in the liver homogenates were significantly higher in HS group than in the other groups (P=0.000),while the concentrations of T-SOD and GSH were much lower than in the other groups (P=0.000).The serum concentrations of ALT and TBIL were significantly higher in HS group than in the other groups (P=0.000).Compare with HS group,the pathological injury was alleviated in HS-NAC group (P=0.000).The neutrophil infiltration level and the concentrations of IL-6,IL-1 β and TNF-α in liver tissue were significantly higher in HS group than in HS-NAC group (P=0.000).Conclusion Oxidative stress may play an important role in the pathogenesis of HS liver injury through its cytotoxic effect and by inducing inflammatory responses.
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Objective To investigate the protective effect of heat shock protein (HSP) 70 on the acute lung injury (ALI) of rats with heat stroke.Methods Sixty four rats were randomly (by employing a random number table) assigned into a sham-heated group (Sham group),heat stress group (HS group),and HS plus gluttamine treatment group (HS+GLN group) and HS plus quercet in treatment group (HS+QU group),16 each.All rats were housed in a artificial climate chamber,with the rats in the sham groups exposed to a temperature of 23 ℃ and humidity of 55％ ± 5％,while the rats of HS,HS+GLN and HS+QU groups to an ambient temperature of 39 ℃ and humidity of 65％.During heat stress or sham heating,rectal temperature (Tr),systolic blood pressure (SBP) and pulse rate (PR) were monitored to observe the difference in heat stress response among the groups.The time point at which the SBP started to drop from the peak level was taken as the point of HS onset.At the onset of HS,heat exposure was terminated,then the rats were immediately removed from the chamber,and returned to room temperature.The rats were scarified 0h and 6h after HS onset respectively.After bronchoalveolar lavage fluid (BALF) was collected,the lungs of all animals were harvested for pathological examination of lung injury.The concentrations of IL-1β,TNF-α and IL-6 in BALF and HSP70 in lung homogenate were measured by using an enzyme linked immunosorbent assay kit.Results Compared with HS and HS+QU groups,the rats in HS+GLN group required significantly greater heat load to induce HS (P＜0.001),and had longer survival time span after HS onset.Compared with Sham group,the concentration of HSP70 in lung homogenate in HS group increased in a time-dependent manner (P＜0.001).In comparison with HS group,the concentration of HSP70 in lung homogenate from HS+GLN group was significantly elevated at each time point (P＜0.001),while the treatment with QU significantly inhibited the expression of HSP70 (P＜0.001).The concentration of IL-1β,TNF-α and IL-6 in BALF significantly decreased in HS+GLN group compared with those in HS group and HS+QU group (P＜0.001).The pathological results showed that the lung injury was milder in HS+GLN group,while the opposite in HS+QU group.Conclusion HSP70 could protect HS rats against ALI by enhancing their thermo-tolerance and inhibiting inflammatory response.
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ObjectiveTo observe the effect of Xuebijing injection pretreatment on systemic inflammatory response induced by severe heat-stroke, and to investigate the mechanism of alleviation of intestinal injury in rats. Methods Thirty-six healthy adult male Wistar rats with grade SPF were randomly assigned into three groups with randomized number method, namely sham group, severe heat-stroke model group, and Xuebijing pretreatment group (XBJ group), with 12 rats in each group. The animals were placed in a pre-warm chamber [temperature (40±2)℃, humidity (65±5)%] in order to induce typical heat-stroke. The duration of heat-stress was 60 minutes, while the animals in sham group were exposed to ambient temperature of 25℃. Arterial blood samples were collected at the beginning and the end of heat-stress, the concentrations of tumor necrosis factor-α(TNF-α), interleukins (IL-1β, IL-6), and lipopolysaccharide (LPS) in peripheral blood were determined by enzyme linked immunosorbent assay (ELISA). The intestinal tissues were harvested after heat-stress, and the pathological changes in intestine tissues were observed after hematoxylin-eosin (HE) staining and under optical microscope. The pathological injury scores were calculated. Immunohistochemistry was performed to determine inducible nitric oxide synthase (iNOS) expression in intestinal tissue. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Western Blot was used to measure the tight junction protein occludin expression.Results The concentrations of TNF-α, IL-1β, IL-6 and LPS in blood of the rats after heat-stress in model group were significantly higher than those of sham group [TNF-α (μg/L): 443.00±110.10 vs. 98.36±44.61, IL-1β (μg/L): 436.37±163.64 vs. 64.24±16.15, IL-6 (μg/L): 342.70±92.42 vs. 54.40±13.22, LPS (μg/L): 0.68±0.22 vs. 0.09±0.02, allP< 0.01], but the levels of these parameters in XBJ group were significantly lower than those of model group [TNF-α (μg/L):340.45±68.57 vs. 443.00±110.10, IL-1β (μg/L): 191.33±82.78 vs. 436.37±163.64, IL-6 (μg/L): 192.21±37.89 vs. 342.70±92.42, LPS (μg/L): 0.43±0.17 vs. 0.68±0.22, allP< 0.01]. Infiltration of inflammatory cells, necrosis and hemorrhage in intestinal mucosa were found in the intestine of heat-stroke animals in model group. The pathological lesions in XBJ group were milder than those of model group, with a decreased pathological injury score compared with model group (2.10±1.15 vs. 3.20±0.67,P< 0.01). The expression of iNOS and apoptosis of cells in intestinal tissue in model group were increased compared with that of sham group, but they were significantly less marked in XBJ group compared with model group [iNOS (adjustedA value): 0.32±0.15 vs. 0.74±0.17, apoptotic index: 0.23±0.08 vs. 0.56±0.07, bothP< 0.01]. The order of expression for occludin protein from high to low was sham group, XBJ group and model group (A value was 0.96±0.25, 0.62±0.20, 0.33±0.11, respectively). Furthermore, there was significant difference in the expression of occludin protein between model group and both XBJ group and sham group (bothP<0.01).Conclusions Xuebijing injection alleviates inflammation and endotoxemia produced by severe heat-stroke in rats. The mechanism may be related to amelioration of oxidative injury, apoptosis, and dysfunction of tight junction protein occludin expression.
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ObjectiveTo study the effect of heat stress on the cytoskeleton and cell cycle of human umbilical vein endothelial cell (HUVEC) in vitro.Methods HUVEC was cultured in vitro in 5%CO2 medium at 37℃ (control group) or 43℃ (heat stress group) for 1 hour. Coomassie brilliant blue R-250 staining was used to determine the effect of heat stress on the cytoskeleton. The cells in heat stress group were subsequently cultured at 37℃in 5%CO2 medium after heat stress for 1 hour, and cell cycle of HUVEC was determined at 0, 6, 12, 18 and 24 hours with flow cytometry.Results Under light microscopy normal cytoskeleton was observed in control group, but thicker and shorter cytoskeleton was found after a rise of temperature, and stress fibers were found in heat stress group. The DNA content of HUVEC at all time points in G0/G1 stage was 38.07%-55.19% after heat stress. The DNA content in control group was 48.57%, and it was 54.06%, 55.19%, 48.23%, 38.07%, and 41.03% at 0, 6, 12, 18, 24 hours in G0/G1 stage in heat stress group. DNA content in S phase was 35.33%-48.18%. The DNA content in control group was 44.62%, and it was 35.33%, 39.50%, 42.50%, 48.18%, and 47.99% at 0, 6, 12, 18, 24 hours in S stage in heat stress group. DNA content in G2/M phase was 5.31%-13.75%. The DNA content in control group was 6.81, and it was 10.61%, 5.31%, 9.27%,13.75%, and 10.98% at 0, 6, 12, 18, 24 hours in G2/M stage in heat stress group. It was demonstrated that compared with control group, the DNA content in G0/G1 stage was significantly increased when the HUVEC were separated from heat stress within 6 hours, and it recovered at a similar level as control group at 12 hours.Conclusion Heat stress can change the cytoskeleton of HUVEC, and cause stagnation at G0/G1 stage in cell cycle.
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Objective To study the effect of heat stress on the permeability,cytoskeleton and cell cycle of human skeletal muscle cell (HSKMC).Methods The HSKMC membrane permeability was detected by calcium ion inflow with flow cytometer,the cytoskeleton was stained by CBB 250,and the cell cycle was determined by flow cytometer.Results After 1 h of heat stress on human HSKMC cells under different temperature gradient,the median level of calcium ion was 91.63 in 43 ℃ heat stress group compared with 22.98 in 37 ℃ control group.As temperature increased,thicker and shorter cytoskeleton and stress fiber were shown under the high power lens of microscope.The DNA expression of skeleton cells at G0/G1 stage was 44.13-62.98 in groups under heat stress.Compared with normal control group,DNA expression was much higher in heat stress group,when HSKMC was cultured under 37 ℃ temperature for another 18 h,it kept decreasing DNA expression to a similar level as control group.Conclusions Heat stress can cause calcium iron inflow resulting in intracellular calcium overload,and affect the cytoskeleton leading to loss of normal web ordered arrangement and increased gap in HSKMC cells,which give rise to blocking cell cycle into G0/G1 stage.