Effect of chronic intermittent hypoxia on AMPK pathway in young rats

AIM: To investigate the effect of chronic intermittent hypoxia on AMP-activated protein kinase(AMPK) pathway in the brain of young rats. METHODS: Part one: SD mice(3~4 weeks old) were randomly divided into 4 groups(n=8): simulated air control group for 2 weeks(2AC), chronic intermittent hypoxia group for 2 weeks(2IH), simulated air control group for 4 weeks(4AC) and chronic intermittent hypoxia group for 4 weeks(4IH). Part two: SD mice(3~4 weeks old) were randomly divided into 2 groups(n=8): chronic intermittent hypoxia group for 4 weeks(4IH) and chronic intermittent hypoxia group treated with AMPK inhibitor for 4 weeks(4IHI). After modeling, the eight-arm maze test was performed. TUNEL method was used to detect the neuronal apoptosis in the hippocampal and prefrontal cortical tissues. The mRNA expression of adenosine A2a receptor was examined by RT-qPCR, and the protein levels of phosphorylated AMPK(p-AMPK) and mammalian target of rapamycin(p-mTOR) were determined by Western blot. RESULTS: Compared with control group, the numbers of reference memory error(RME), working memory error(WME) and total error(TE) in 2IH group and 4IH group significantly increased(P<0.01). Compared with 2IH group, the numbers of errors in 4IH group also increased significantly(P<0.01). Compared with 4IH group, the values in 4IHI group significantly decreased. Compared with control group, the neuronal apoptosis of hippocampus and prefrontal cortex in 2IH group and 4IH group increased, and that in 4IH group was more evident(P<0.05). In 4IHI group, the neuronal apoptosis decreased. The mRNA expression of adenosine A2a receptor in the hippocampal and cortical tissues in 2IH group and 4IH group was higher than that in control group. The protein level of p-AMPK was higher, and p-mTOR was lower in 2IH group and 4IH group, and those in 4IH group were more evident(P<0.05). Compared with 4IH group, the protein level of p-AMPK was lower, and p-mTOR was higher in 4IHI group. CONCLUSION: Chronic intermittent hypoxia induces neuronal apoptosis, resulting in impairment of learning and memory in a time-dependent manner by upregulating adenosine A2a receptor, activating AMPK activity, and inhibiting mTOR phosphorylation in rats.     

Effect of chronic intermittent hypoxia on memory and CREB expression in growing rats

AIM: To observe the alterations in cognition of growing rats exposed to chronic intermittent hypoxia (CIH) and to explore its underlying mechanisms. METHODS: Forty male Sprague-Dawley rats (3-week-old～4-week-old and 80 g to 100 g), which had been trained to complete the 8-arm (4-arm baited) radial maze, were randomly divided into 4 groups: 2-weeek-CIH group (2IH), 4-week-CIH group (4IH), 2-week-control group (2C) and 4-weeek-control group (4C). The intermittent hypoxia model was induced by putting the animals in an intermittent hypoxia cabin. When intermittent hypoxia was terminated, spatial memory of these growing rats was tested by 8-arm (4-arm baited) radial maze task, then, one rat in each group was randomly selected for ultrastructural observation. The hippocampus and prefrontal cortexes of the rats were collected for analyzing the mRNA and protein expression of CREB by RT-PCR and Western blotting, respectively. RESULTS: (1) In the 8-arm (4-arm baited) radial maze task, the results indicated that the rats in the 4 groups displayed significant difference in their performance assessed by three measuremens: the reference memory error, the working memory error and total memory error (P<0.05, respectively). (2) Early apoptosis and destructure of the neurons in the hippocampus and prefrontal cortex were observed under electron microscope in CIH exposed groups, especially in 4IH group, but not detected in 2C and 4C groups. (3) The expression levels of CREB mRNA and p-CREB protein in 2IH and 4IH groups were less than those in 2C and 4C groups in the hippocampus and prefrontal cortex (P<0.05, respectively), especially in the hippocampus of 4IH group (P<0.01). No difference was found within control groups (P>0.05, respectively). CONCLUSION: Exposure to experimentally-induced IH in growing rats is associated with time related spatial memory impairment. Chronic intermittent hypoxia leads to the disorders of neuron ultra-structure in memory related brain regions. It also inhabits the CREB transduction, expression and CREB phosphorylation, decreases the synthesis of the memory related protein. These factors maybe contribute to learning-memory impairment of growing rats exposed to chronic intermittent hypoxia.     

Effect of endoplasmic reticulum stress on brain injury following chronic intermittent hypoxia in growing rats

AIM: To explore the role of endoplasmic reticulum stress (ERS) in brain injury following chronic intermittent hypoxia in growing rats and the protective effect of treatment with salubrinal. METHODS: Healthy male SD rats (3~4-week-old, 100~120 g, n=64) were randomly assigned to 8 groups (8 rats in each group):the groups of intermittent hypoxia for 2 and 4 weeks (2IH and 4IH), the groups of control (C) for 2 and 4 weeks (2C and 4C), the groups of dimethylsulfoxide (DMSO) for 2 and 4 weeks (2DMSO and 4DMSO) and the groups of salubrinal for 2 and 4 weeks (2SAL and 4SAL). The 8-arm radial maze was used to assess the working memory error (WME), reference memory error (RME) and total error (TE) of the rats. The changes of neuronal apoptosis in the hippocampus were observed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The activity of superoxide dismutase (SOD), and the protein levels of endoplasmic reticulum stress marker compounds, C/EBP homologous protein (CHOP), phosphorylated eukaryotic translation initiation factor 2 alpha (p-eIF2α) and phosphorylated protein kinase R-like endoplasmic reticulum kinase (p-PERK), were analyzed. RESULTS: Chronic intermittent hypoxia (CIH) significantly increased RME, WME, TE and neuronal apoptotic index (AI) (P<0.01), and decreased the activity of SOD in the hippocampus and serum (P<0.01). The protein levels of p-PERK and CHOP progressively increased in hippocampus in IH groups (P<0.01), and p-eIF2α was downregulated (P<0.05). Treatment with salubrinal significantly decreased RME (P<0.05), WME (P<0.05), TE (P<0.01) and AI (P<0.01), and increased the activity of SOD (P<0.01). Salubrinal induced the phosphorylation of eIF2α significantly after CIH in hippocampus and downregulated the level of CHOP (P<0.01). CONCLUSION: Chronic intermittent hypoxia upregulates the protein levels of p-PERK and CHOP in the hippocampus, and decreases p-eIF2α protein and the activity of SOD. Salubrinal, a selective inhibitor of eIF-2α dephosphorylation, increases the activity of SOD and prevents CHOP protein activation throughout CIH exposure. Our findings suggest ERS-mediated cell apoptosis is one of the underlying mechanisms of cognitive dysfunction in OSAHS children. Further, a specific ERS inhibitor salubrinal should be tested for neuroprotection against CIH-induced brain injury.     

Effect of N-acetyl-L-cystein on blood pressure and endothelial function in aorta of rats exposed to chronic intermittent hypoxia

AIM: To investigate the effect of N-acetyl-L-cystein (NAC) on blood pressure and endothelial function in the aorta of the rats exposed to chronic intermittent hypoxia (CIH). METHODS: Thirty healthy male SD rats were randomly divided into 3 groups: control group, CIH group and CIH+NAC group. The systolic blood pressure (SBP) was measured with tail-cuff me-thod. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression of endothelial nitric oxide synthase (eNOS） and endothelin-1 (ET-1) in the thoracic aorta. The protein expression of eNOS in the thoracic aorta was examined by Western blotting. The levels of ET-1 in the thoracic aorta and serum were detected by radioimmunoassay. The serum nitric oxide was determined by nitric acid reduction method.The superoxide dismutase (SOD) activity in peripheral blood plasma was detected by xanthine oxidase method.The serum malondialdehyde content was detected by thiobarbituric acid method, and superoxide anion (O-·2) in thoracic aorta was determined by chemical colorimetric method. RESULTS: Compared with the control animals, CIH exposure was associated with decreased SOD level, and NAC-treated CIH animals showed recovery in SOD level. NAC treatment prevented CIH-induced hypertension as well as CIH-induced increase in MDA. The aorta eNOS mRNA and protein, and serum NO levels in CIH group were lower than those in control group, and those in NAC treatment group were higher than those in CIH group. The increases in ET-1 mRNA,ET-1 protein and O-·2 levels in the aorta, and the elevated circulating ET-1 level were also observed in CIH-exposed animals. Treatment with NAC significantly decreased the mRNA and protein levels of ET-1, the O-·2 content, and the circulating ET-1 level in CIH-exposed animals. CONCLUSION: NAC protects endothelial function and alleviates hypertension by suppressing the oxidant stress in the aorta tissues, indicating that oxidant stress may be involved in the mechanism of endothelial disorder of CIH-induced hypertension.     

Effect of intermittent hypoxia on bladder detrusor cell apoptosis and regulatory mechanism of Alpiniae oxyphyllae Fructus

AIM To investigate the effect of intermittent hypoxia （IH） on bladder detrusor cells apoptosis and calcium channel, and to discuss the regulatory mechanism of Alpiniae oxyphyllae Fructus （AOF）. METHODS IH model of bladder detrusor cells was established by treating the cells with 6 cycles of 5% O₂ for 60 min and 20% O₂ for 30 min. Human bladder detrusor cells were cultured in vitro, randomly divided into 6 groups, each group had 8 holes. P₂X₃ receptor antagonist + IH （A） group, M₃ receptor antagonist + IH （B） group, β₃ receptor antagonist + IH （C） group, AOF + IH （D） group, saline + IH control （NC） group and air simulation control （AC） group were set up. The cells density and morphology were identified by the methods of counting chamber and immunofluorescence light microscopy （LM） after interventions. The apoptosis was analyzed by flow cytometry. Calcium channel expression was detected by patch clamp. RESULTS （1） Compared with the cells in AC group, the cells density and activity were significantly increased in NC group （P<0.05）; some cells appeared protrusions, turned round and blur in cell borders. （2） The results of immunofluorescence for detecting α-SMA protein expression showed that, compared with the cells in group AC, the mean absorbance （MA） in group NC was significantly increased （F=3.25, P<0.05）; compared with the cells in group NC, that in group A and group D was both decreased significantly （P<0.05）. （3） Compared with the cells in group AC, the apoptotic rate was significantly decreased in group NC （P<0.05）; Compared with the cells in group NC, the apoptotic rates in group A and group D were both significantly increased （P>0.05）. （4） Compared with the cells in group AC, calcium ion channel expression was significantly decreased （P<0.05）. Compared with the cells in group NC, calcium ion channel expression in AOF （100 mg/L） and AOF （50 mg/L） group was significantly increased （P<0.05）. CONCLUSION IH regulates bladder detrusor cells proliferation and apoptosis through P₂X₃ bladder nerve receptors, high or moderate dose of AOF may change calcium channel and play a protective role in IH induced cell damage.     

Impairment of left ventricular function and mechanism analysis after intermittent hypoxia

Intermittent hypoxia (IH) is a direct consequence of obstructive sleep apnea syndrome (OSAS), which results in left ventricular dysfunction, remodeling and myocardial cell injury. Understanding the mechanisms of OSAS is important for us to prevent and treat the cardiovascular complications in the clinical practices. We summarize the effects of IH on left ventricular function, and analyze the mechanisms at the cellular and molecular levels, including oxidative stress, ion exchangers and inflammation. In addition, the effects of endothelin-1 and hypercapnia on IH-induced cardiac injury are discussed.     

Effect of ischemia or hypoxia on vascular endothelial growth factor production in rat myocardium and its significance

AIM:To determine the relationship between ischemia, hypoxia and the production of vascular endothelial growth factor in rat myocardium and its basic mechanism. METHODS:(1) 28 Wistar rats were randomly divided into 4 groups: group A, normal control;group B, 1 day's acute myocardial infarction;group C, 3 day's acute myocardial infarction;group D, 7 day's acute myocardial infarction. (2) Rat cardiac myocytes cultured were primarily divided into some groups, hypoxia incubated 24 hours; PMA groups, hypoxia incubated 24 hours with PKC activator (PMA), A 0 ng/mL; B 10 ng/mL; C 100 ng/mL; D 1 000 ng/mL; Chelerythrine groups, hypoxia incubated 24 hours with PKC inhibitor (chelerythrine), A 0 nmol/L; B 10 nmol/L. (3) By computer scanned and quantitated, vascular endothelial growth factor (VEGF) protein was detected with immunohistochemical technique. RESULTS:The longer time of ischemia and hypoxia was, the higher the VEGF production.The relat ionship was found between the time of ischemia or hypoxia and the production of VEGF.The product ion of VEGF protein was further promoted by PMA with different concentrat ion, decreased by chelerythrine.CONCLUSION: Ischemia or hypoxia strongly stimulated the production of VEGF in myocardium, which played an important role in autoprotecting of ischemic or hypoxic myocardium. Hypoxia-induced PKC activation is one kind of basic mechanisms in this course.     

Effect of NAC on oxidant stress and apoptosis in the hippocampal CA1 region of rats exposured to chronic intermittent hypoxia

AIM: To investigate the effect of N-acetylcystein (NAC) on oxidant stress, neuron apoptosis in the hippocampal CA1 region of rats exposured to chronic intermittent hypoxia (CIH). METHODS: 30 healthy male Wistar rats were randomly divided into three groups of 10 each, a CIH group, a NAC therapeutic group and a control group. The levels of MDA and SOD were detected by colorimetric method. Immunohistochemistry was used to examine the expression of p-JNK and TUNEL was used to detect the neuron apoptosis in the hippocampal CA1 region. RESULTS: The level of MDA in NAC group were lower than that in CIH group［(1.71±0.43) μmol/g protein vs （1.37±0.26) μmol/g protein, P<0.05)］. The activity of SOD in NAC group was higher than that in CIH group［(44.94±14.01) 103 NU/g protein vs(57.66±14.07) 103 NU/g protein, P<0.05)］. The expression of p-JNK protein and the apoptotic indices ［(0.39±0.16), (0.20±0.11)］ in NAC group were significantly lower than those in CIH group ［(0.53±0.10), (0.32±0.18), all P<0.05］. CONCLUSION: NAC protects hippocampal neuron from apoptosis by suppressing the oxidant stress in the hippocampal CA1 region and inhibiting the activation of JNK signaling pathway.     

Effect of GLP-1 receptor agonist on lipolysis in adipose tissue of obese mice and its underlying mechanism

AIM: To investigate the effects of glucagon-like peptide-1(GLP-1) receptor agonist exendin-4 on white adipose tissue (WAT) and the underlying mechanisms. METHODS: Male C57BL/6J mice (8 weeks) were challenged by high-fat diet for 12 weeks, and were randomly divided into saline group and exendin-4 group. The mRNA expression of sirtuin 1(SIRT1), adipose triglyceride lipase (ATGL), TNF-α and adiponectin of WAT was detected by real-time PCR. 3T3-L1 adipocytes or mouse embryonic fibroblasts cells were treated with exendin-4 for 24 h. The protein levels of SIRT1, ATGL and hormone-sensitive lipase (HSL) were determined by Western blot.RESULTS: Exendin-4 significantly decreased epididymal fat weight, fasting blood glucose and serum triglyceride levels (P<0.05), and reduced body weight and serum TNF-α level. The mRNA expression of SIRT1, ATGL and adiponectin in WAT was all significantly up-regulated by exendin-4, which were contrary to the down-regulation of TNF-α mRNA expression (P<0.05). Exendin-4 promoted the protein expression of SIRT1, ATGL, and HSL in 3T3-L1 adipocytes in a dose-dependent manner. Less lipid droplets with up-regulation of lipolytic protein expression were observed when combined with SIRT1 agonist treatment, which were suppressed by SIRT1 inhibitor. Deletion of SIRT1 led to larger adipocytes with more lipid droplets, and the effect of exendin-4 on the lipolysis disappeared when SIRT1 was deficient.CONCLUSION: Exendin-4 promotes lipolysis in WAT of obese mice via activation of SIRT1.     

Effects of EGb761 on synaptophysin expression in hippocampus of vascular dementia rats

AIM: To investigate the effects of Ginkgo biloba extract 761 (Egb761) on synaptophysin (SYN) expression in hippocampus of vascular dementia (VD) rats.METHODS: VD rat models, established by repeatedly cerebral ischemia/reperfusion, were randomly divided into two groups: model group and EGb761 treated group (both n=30), and another 30 condition-matched rats were selected as the sham-operated controls. Spatial learning and memory abilities of rats were assessed by Morris water maze (MWM) task, and SYN expression in hippocampal formation of rats in different groups was detected by immunohistochemical technique and image analysis.RESULTS: The MWM escape latency (EL) in model group was highly longer than that in the sham-operated group (P<0.01), while the EL of EGb761-treated group was significantly shorter than that in model group, but still longer than that in the sham-operated group at 1 m, 2 m and 4 m after VD modeling operation (P<0.05 or P<0.01). Immunohistochemical analysis showed that the SYN immunoreactive expression in hippocampal formation in model group greatly decreased and mean optical density of SYN expression highly increased compared with both sham-operated group and EGb761-treated group at three time points (P<0.01).CONCLUSION: EGb761 can increase the expression of SYN in hippocampus, which may be one of important mechanisms of EGb761 in improving learning and memory dysfunction of VD rats.     

Effect of intermittent hypobaric hypoxia preconditioning on expression of Ngb and Bcl-2 in hippocampal CA1 region in rats with global cerebral ischemia-reperfusion

AIM:To study the effect of intermittent hypobaric hypoxia preconditioning (IHHP) on the expression of neuroglobin (Ngb) and Bcl-2 in hippocampal CA1 region in the rats with global cerebral ischemia-reperfusion. METHODS:The Wistar rats were randomly divided into sham group, IHHP control group, global cerebral ischemia-reperfusion group (I/R group), and IHHP+I/R group. The 4-vessel occlusion rat model of Pulsinelli was performed in the rats in I/R group and IHHP+I/R group, in which the common carotid artery was occluded for 8 min before reperfusion. Thionine staining and immunohistochemical staining were used to observe the histological changes of the hippcampus and the expression of Ngb and Bcl-2 in the hippocampal CA1 region. RESULTS:A significant increase in the quantity of surviving cells in the hippocampal CA1 region was observed in IHHP+I/R group as compared with I/R group. There was a significant increase in the expression of Ngb and Bcl-2 in the hippocampal CA1 region in IHHP+I/R group as compared with I/R group. CONCLUSION: Through the up-regulation of hippocampal Ngb and Bcl-2 expression, intermittent hypobaric hypoxia preconditioning may play a role in neuroprotection by reducing hippocampal neuronal apoptosis from ischemia-reperfusion.     

Effect of concentrated decoction of Chinese herbal compound Buyanghuanwutang on cAMP-PKA-CREB signaling pathway in hippocampus of rats with vascular dementia

AIM: To evaluate the role of concentrated decoction of Chinese herbal compound Buyanghuanwutang (BYHWT) in cyclic adenosine monophosphate(cAMP)-protein kinase A(PKA)-cAMP response element-binding protein(CREB) signaling pathway in hippocampus of rats with vascular dementia (VD). METHODS: The rats were randomly divided into sham operation group (sham-operated rats treated with normal saline), VD model group (VD rats treated with normal saline), BYHWT treatment group (VD rats treated with BYHWT) and nimodipment treating group (VD rats treated with nimodipine). The rat model of VD was build by the method of four-vessel occlusion. The rats in all 4 groups were administered with the corresponding reagents for successive 30 days. The content of cAMP was measured by radioimmunoassay. The expression of PKA catalytic subunit (PKAc) was observed by Western blotting. The changes of DNA-binding activity of CREB in rat hippocampus were detected by electrophoretic mobility shift assay. RESULTS: The content of cAMP, the expression of PKAc and the DNA-bingding activity of CREB in the hippocampus of VD rats were lower than those in the hippocampus of sham-operated rats (P<0.01). The above indexes in both nimodipine treatment group and BYHWT treatment group were definitely higher than those in VD model group (P<0.01). CONCLUSION: BYHWT increases the content of cAMP, the expression of PKAc and the DNA-binding activity of CREB in VD rat hippocampus, thus strengthening the cAMP-PKA-CREB signaling pathway.     

Effect of ginsenoside Rb1 on liver cell pyroptosis in hyperlipidemia rats and its possible mechanism

AIM:To discuss the mechanism of ginsenoside Rb1 against liver lipid deposition by observing the effect of ginsenoside Rb1 on liver cell pyroptosis in hyperlipidemia rats. METHODS:Totally 32 healthy SPF rats were randomly divided into control group, model group, ginsenoside Rb1 group and simvastatin group. The rats in control group was given the basic feed, while the others were given high-fat diet. The rats in ginsenoside Rb1 group and simvastatin group were given corresponding drugs. The rats in control group and model group were intraperitoneal injected with equal volume of saline. Eight weeks later, the serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were tested by the automatic biochemistry analyzer. The pathological changes of the liver tissues were observed with HE staining. The protein and mRNA expression levels of pyroptosis-related factors NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were detected by Western blot and RT-qPCR. RESULTS:Compared with control group, the serum levels of TC, TG and LDL-C in model group were increased significantly (P<0.01), and the HDL-C content was decreased significantly (P<0.05). The steatotic liver cells covered the visual field. The mRNA and protein expression levels of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were increased significantly (P<0.01). Ginsenoside Rb1 significantly decreased the serum levels of TC, TG and LDL-C (P<0.05), and significantly increased the content of HDL-C (P<0.01). Ginsenoside Rb1 also significantly decreased the degree of steatosis, and the number and size of lipid droplets. The mRNA and protein expression levels of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were decreased significantly (P<0.05 or P<0.01). CONCLUSION:Ginsenoside Rb1 atte-nuates liver injury and inhibits liver lipid deposition in hyperlipidemia rats by reducing the expression of hepatic pyroptosis-related factors.     

Dynamic expressions of synapsin I and phosphorylated synapsin I in hippocampus of vascular dementia rats

AIM: To observe the dynamic changes of synapsin I expression and its phosphorylation in hippocampus in vascular dementia (VD) rats. METHODS: Eighty SD rats were randomly divided into sham-operated group (n=40) and VD model group (n=40), and the latter were established by repeatedly clipping the common carotid arteries with an intraperitoneal injection of sodium nitroprusside solution in anesthetized condition. The synaptic ultrastructural changes in hippocampal CA1 region and the expression levels of synapsinⅠ and phosphorylated synapsinⅠin hippocampus were observed by TEM and immunohistochemical staining method respectively in both sham-operated group and VD model group at 15 d, 1 month, 2 months and 4 months time points. RESULTS: No obviously pathological changes to CA1 area synapse were found in SO group. In model group rats, synaptic circa membrane ambiguity and fusion, synaptic circa membrane structure decreased the postsynaptic density, reduced synaptic vesicles and vesicle cluster. Above pathological changes became gradually severe along with the time prolongation after model-making operation. Compared with sham-operated group, the expression of synapsin I significantly reduced in CA1 region (P<0.01). However, no significant change in molecular layer of DG region (P>0.05) in model group was observed. The number of p-synapsin I positive neurons in DG and hippocampal CA1 region was less in model group than that in sham-operated group (P<0.05, P<0.01). The average absorbance values of p-synapsin I positive neurons in DG and hippocampal CA1 region in model group were decreased at 15 d and 1 month time points (P<0.01), but increased in CA1 region (P<0.01) and unchanged in DG at 2 months and 4 months time points (P>0.05). CONCLUSION: The damaged synaptic structure and depressed expression of synapsin I and its phosphorylation in presynaptic parts of hippocampus induced by repeatedly cerebral ischemia/reperfusion may contribute to the synaptic transmission disorders, especially the presynaptic disorder which may be one of the important pathogenesis of the initiation and development in vascular dementia rats.     

Effect of tissue kallikrein gene treatment on blood pressure in type 2 diabetic rats and its mechanism

AIM:To study the effect of tissue kallikrein gene (HK) treatment on blood pressure in type 2 diabetic rats and its mechanism. METHODS:Male Wistar rats were injected with low dose streptozotocin and fed with diets enriched in fat and sugar to form type 2 diabetic model. Recombinant adeno-associated viral vectors (rAAV)-mediated HK gene (HK group) or LacZ gene (LacZ group) was introduced to the diabetic rats. The systolic blood pressure was measured every 2 weeks. The acetylcholine (Ach)-dependent vasodilation response, the synthesis of nitric oxide (NO), the expression of endothelin-1 (ET-1) and endothelin-A receptor (ETA-R) in the aorta were detected. RESULTS:(1) Systolic blood pressure was significantly higher in diabetic rats than that in normal control rats. In HK group, systolic blood pressure was significantly reduced within 2 weeks after injection with rAAV·HK, reached near normal levels at 4 weeks and kept until the experiments ended (16 weeks). (2) In LacZ group, Ach-dependent vasodilation response of isolated aorta was markedly decreased than that in HK group (P<0.01). (3) The concentration of NO in the aorta of HK group were significantly higher than those in LacZ group. The expression of ET-1 and ETA-R mRNA were significantly decreased in HK group compared with those in LacZ group (P<0.01). CONCLUSION:rAAV-mediated HK gene delivery efficiently lowed blood pressure and attenuated the endothelial function partly through increasing the concentration of NO and inhibiting the expression of ET-1 and ETA-R of aorta in type 2 diabetic rats.     

Effect of exogenous GABA in nucleus accumbens of hypothalamus on gastric function in rats and its potential mechanism

AIM:To investigate whether glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) signaling pathway is involved in regulating the effects of exogenous γ-aminobutyric acid (GABA) in hypothalamic nucleus accumbens (NAc) on discharge activity of gastric distension (GD) sensitive neurons, gastric motility and gastric acid secretion in rats. METHODS:Fluorescence immunohistochemistry was used to observe the expression of GABA-A receptor (GABA-AR) and GLP-1R in rat NAc. The single-cell discharge recording experiment was used to observe the effects of GABA, GLP-1 and their receptor antagonists on the excitability of GD neurons in rat NAc. Implantation of cannula in rat NAc and injection of GLP-1, GLP-1R antagonist exendin 9-39 (Ex9) and GABA-AR antagonist bicuculline (BIC) were performed to investigate the changes of gastric motility and gastric acid secretion in the rats. RESULTS:GABA-AR and GLP-1R immunoreactive positive neurons coexisted in rat NAc. GABA inhibited the discharge activity of GD neurons in NAc, but this inhibitory effect was antagonized by BIC and partially blocked by Ex9. Microinjection of GABA into rat NAc promoted gastric motility and gastric acid secretion, which was antagonized by BIC and partially blocked by Ex9. CONCLUSION:Exogenous GABA in NAc may be involved in the regulation of gastric motility, gastric acid secretion and GD neuron excitability in the rats through GABA-AR signaling pathway. The promotion of GABA-AR signaling pathway is partially inhibited by GLP-1R signaling pathway.     

Effect of mininally modified low density lipoprotein on the adhesive function of vascular endothelial cell and its mechanism

AIM: To observe the effect of MM-LDL (minimally modified LDL) on the interaction between human umbilical vein endothelial cell (HUVEC) and U937 monocyte-like cell line and the exporession of vascular cell adhesion-1 (VCAM-1), intercellular adhesion molecule-1(ICAM-1), P-selectin.METHODS:The adhesive percentage between HUVEC treated with MM-LDL and U937 was determined by counting and the expression of VCAM-1, ICAM-1, P-selectin were examined by ELISA. RESULTS: Treatment of HUVEC with MM-LDL (75 mg/L) for 4 hours significantly increased adhesion of U937 to HUVEC ( P <0.01) and did not induce the surface expression of VCAM-1, ICAM-1, P-selectin . Recombination tumor necrosis factor-alpha (rTNF_α) 5.0 μg/L, as a positive control, induced the expression of these adhesion molecules ( P <0.05). Prolonged (18 h) exposure to MM-LDL resulted in the expression of P-selectin, but not VCAM-1.CONCLUSION: the adhesion of monocytes to endothelial cells induced by MM-LDL is not mediated by VCAM-1, ICAM-1. P-selectin induction may be partly involved in the process.     

Effect of cilazapril on pulmonary vascular endothelial dysfunction in hypoxic rats

AIM:To study the effect of cilazapril on pulmonary vascular endothelial dysfunction in hypoxic rats. METHODS:The structure and function of endothelium in hypoxic rats were studied by biochemical analysis, radioimmunoassay, transmission electron microscope and correlated with hemodynamic. RESULTS:1) The change and damage of ultrastructure in endothelial cell (EC) were obsevered in hypoxic rats. 2) The contents of plasma nitric oxide (NO) and superoxide dismutase (SOD) activity in blood as well as endothelial nitric oxide synthase (eNOS) activity in the lung tissue were significantly lower in the hypoxic rat than those in contral animals. The concentrations of plasma endothelin-1(ET-1) and angiotensin converting enzyme(ACE) as well as malondialdehyde(MDA) were significantly higher in the hypoxic rat than these in contral animals. The relaxing and contracting factors had a significant positive/negative correlation with mean pulmonary artery pressure (mPAP). 3) Cilazapril significantly decreased the level of ET-1 and ACE and significantly increased the level of NO and activity of eNOS and SOD. At the same time, cilazapril extenuated hypoxia-induced injuries of EC. CONCLUSION:The results indicate that damaging structure and dysfunction of EC existes in hypoxic rats. The cilazapril effectively preventes and treates the chronic hypoxic PH by relieving the injury and improving secretion in EC.