Inducible nitric oxide synthase and arterial pressure regulation

AIM and METHODS:To clarify the role of inducible nitric oxide synthase (iNOS) in the regulation of blood pressure,in the present study, we examined the effect of aminoguanidine (AG), a selective inhibitor of iNOS on the hemodinamical response of Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to low (0.3%) or high (8%) sodium chloride (NaCl) infusion by chronical in vivo hemodynamic experiment, and the effect of NaCl or NaCl plus AG infusion on urinary nitrate (NO₃)/nitrite (NO₂), the end product of nitric oxide (NO), excretion by Greiss Reaction. Furthermore, NOS activity assay was also carried out to probe the effect of NaCl and AG on calcium-dependent or independent NOS activity in renal tissue. RESULTS:1. High or low NaCl-infused DR rats and low NaCl-infused DS rats have no hemodinamical response to AG, however, the hypertensive effect of high NaCl (8%) infusion on DS rats were greatly amplified by co-infusion of AG. 2. Administration of high NaCl significantly elevated the iNOS activity of renal tissue, and greatly increased urinary NO₃/NO₂ excretion. CONCLUSION:Inducible NOS is an important modulator of arterial pressure, especially in case of higher blood pressure.     

Correlation between intraventricular pressure and early phase proto-oncogene expression in volume overload rats

AIM: To investigate the effect of intraventricular pressure change by volume overload (VOL) on expression of proto-oncogene c-fos,c-jun,c-myc and egr-1. METHODS: Left ventricular systolic pressure(LVSP) and left ventricular end diastolic pressure (LVEDP) of rat with VOL induced by aortacaval fistula operation and rats of control group were measured at 30 min, 1, 4, 6, 12 and 48 h after the operation,these mRNAs at the foregoing time points were measured by slot bloting method and quantified with densitometry. RESULTS: Be compared with the control group, VOL rats LVSP decreased (P＜0.05) and declined most remarkably at 48 h,LVEDP elevated significantly at 30 min (P＜0.05), reached a maximal value at 12 h and the levels of control group at 48 h (P＞0.05) after the operation.The proto-oncogene expression signals were not detected in the control,negative controls and VOL rats at 30 min after the operation. The c-fos,c-jun and egr-1 mRNA signals appeared earlier,at 1 h, and c-myc mRNA increased later at 4 h.All reached peak value at 4 h and then declined gradually.The c-fos mRNA were not detected at 48 h. The c-myc,c-0jun and egr-1 mRNA persisted throught the entire observation period from 1 h to 48 h. CONCLUSIONS: During VOL early phase the overload have effect on expression of the proto-oncogene mRNA,c-fos,c-jun and egr-1 mRNA appear earlier, c-myc later,egr-1,c-jun and c-myc persist longer period, but the expressions do not strengthen with the ventricule wall load increase.This sequential induction pattern may reflect the time course regularity of the proto-oncogenes expression induced by VOL,and indicate the proto-oncogenes expression initiate while the heart load accumulate some extent and duration and the load magnitude may not play a critical role.     

The protection of the hepatic ischemic preconditioning is concerned with the NO/ET-1 system

AIM: To study the relationship between the disturbance of nitric oxide/endothelin-1(NO/ET-1) and hepatic ischemia/reperfusion(I/R) injury as well as the regulation of NO/ET-1 system by hepatic ischemic preconditioning(IPC). METHODS: The changes of NO/ET-1 system and their relationship with hepatic I/R injury were compared between I/R group and IPC+I/R group in a rat hepatic I/R model. Two hours after reperfusion, the liver tissues were detected by RT-PCR to see whether there was inducible nitric oxide synthase (iNOS) mRNA expression. RESULTS:In the acute phase of hepatic reperfusion, the ratio of NO/ET-1 was reduced, which was due to a significant reduction of NO₂^-/NO₃^- (the metabolic product of NO) and significant elevation of ET-1 in the blood plasma. The content of ALT, AST, LDH and TNF-α in blood plasma, and of MDA in liver tissue were increased but ATP in liver tissue was reduced, the hepatic damage was deteriorated. The protection of the hepatic IPC was concerned with the elevation of the ratio of NO/ET-1 caused by the elevation of NO₂^-/NO₃^-, and reduction of ET-1 as well. There was no iNOS mRNA detected in the liver tissues.CONCLUSION: Hepatic I/R injury is related to the disturbance of NO/ET-1. The protection of the hepatic IPC in the acute phase might be conducted by its regulation of NO/ET-1 system. The cNOS rather than the iNOS generated the NO in this situation.     

Study on the relationship between melatonin and hepatic encephalopathy

AIM:To explore the relationship between change of serum melatonin (MT) and pathogenesis of hepatic encephalopathy (HE). METHODS: Changes of MT level in sera of cirrhosic patients with HE and without HE were determined by ELISA, normal serum served as control. The change of serum MT level in exacerbation and remission in HE was also determined.RESULTS:MT level in patients with HE was higher than that withour HE (P＜0.01). MT levels of both groups were higher than that of normal group (P＜0.01). They were (308.53±59.07) ng/L, (139.85±34.59)ng/L,(77.73±28.41)ng/L, respectively. Serum MT level in exacerbation was higher than that in remission (P＜0.01), they were (301.52±66.42)ng/L and (147.81±23.31) ng/L, respectively. CONCLUSION: The elevation of MT content in sera may be closely related to the onset of hepatic coma.     

Bortezomib attenuates LPS-induced inflammatory response of human monocytes through regulating miR-223/NLRP3 signaling pathway

AIM To investigate the effects of bortezomib (BTZ) on microRNA-223 (miR-223)/nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) signaling pathway and lipopolysaccharide (LPS)-induced inflammatory response of human monocytes. METHODS Monocytes were isolated and purified from peripheral blood of rheumatodid arthritis (RA) patients. The levels of interleukin-6 (IL-6), IL-1β and tumor necrosis factor-α (TNF-α) in supernatants of the monocytes were determined by ELISA, and the optimal induction time of LPS and the optimal treatment concentration of BTZ were selected according to the levels of IL-6, IL-1β and TNF-α. The monocytes were divided into control group, LPS induced group and BTZ group. The level of miR-223 in the monocytes was measured by RT-qPCR, and the protein levels of NLRP3, caspase-1, suppressor of cytokine signaling 1 (SOCS1) and SH2 domain-containing inositol phosphatase-1 (SHIP-1) in the monocytes were determined by Western blot. RESULTS The monocytes successfully isolated and purified from the peripheral blood of RA patients were spherical, evenly distributed and regular in shape.And after LPS induction for 24 h, the cells were mostly spindle-shaped and aggregated. According to the levels of IL-6, IL-1β and TNF-α, the optimal induction time of LPS was 24 h, and the optimal concentration of BTZ was 50 nmol/L. Compared with control group, the levels of miR-223, SOCS1 and SHIP-1 in LPS induction group were significantly decreased (P<0.05), and the levels of NLRP3 and caspase-1 were significantly increased (P<0.05). Compared with LPS induction group, the levels of miR-223, SOCS1 and SHIP-1 in BTZ group were significantly increased (P< 0.05), and the levels of NLRP3 and caspase-1 were significantly lowered (P<0.05). CONCLUSION Bortezomib may block the activation of miR-223/NLRP3 signaling pathway, thus reducing the secretion of inflammatory factors in LPS-induced human monocytes.     

Intracellular calcium alterations induced by endotoxin and IL-1β in rabbit hypothalamic neurons

AIM: To investigate intracellular free calcium ( [Ca²⁺]i ) alterations in hypothalamus of febrile rabbits induced by endotoxin (ET), and compare with the effect of ET and IL-1β on i in hypothalamic neurocytes from normothermia rabbits. METHOD: The concentration of [Ca²⁺]i was determined by using spectrofluorometer and fluorescent Ca²⁺ probe fura-2 /Am. RESULTS: 1. A minute dose of ET (2 ng/mL) induced a significant rise in [Ca²⁺]i in hypothalamic neurocytes from normothermia rabbits. The rise in [Ca²⁺]i in hypothalamic neurocytes from febrile rabbits induced by intravenous injection of ET was also observed. 2. In hypothalamic neurocytes from normotheria rabbits, IL-1β failed to affect [Ca²⁺]i at concentrations of 100, 500, 1 000ng/mL, respectively. CONCLUSION:The action site of low concentration of calcium that plays a regulatory role during fever seems unlikely to be in cytosolic compartment of hypothalamic neurons. The change of [Ca²⁺]i in hypothalamic neurocytes by ET can not be considered the direct effect of IL-1β.     

The activation effect of maize pollen polysaccharides on human thoracic cavity macrophages

AIM: To study the activation effects of maize pollen polysaccharides(PPM) on human thoracic cavity macrophage (hTMΦ). METHODS: Activities of lactate dehydrogenase(LDH) and acid phosphatase (ACP) in the hTMΦ were detected by automatic biochemical analyzer, and the level of tumor necrosis factor alpha(TNF-α) and interleukin-6(IL-6) in the hTMΦ was analyzed by radioimmunoassay, after hTMΦ were cultured with 0.312, 0.625, 1.250, 2.500, 5.000 mg/mL PPM-RPMI 1640 for 24 and 48 hours in vitro. RESULTS: The activities of LDH and ACP increased in the hTMΦ induced by PPM, and the levels of TNF-α and IL-6 in the hTMΦ induced by PPM increased markedly too. And the induced expression effect of TNF-α and IL-6 is associated with the concentration of PPM, and time for PPM inducing. CONCLUSION: PPM can induce cytokines secretion in hTMΦ, and activate hTMΦ in vitro.     

Protective effect of C1q/tumor necrosis factor-related protein 3 on vascular endothelium in rats with hyperuricemia

AIM To study whether C1q/tumor necrosis factor （TNF）-related protein 3 （CTRP3）protect vascular endothelium in rats with hyperuricemia and its potential mechanisms. METHODS An animal model of hyperuricemia was established by using male SD rats drinking 10% fructose water （n=10）. The rats drinking normal water served as normal controls （n=10）. After 12 weeks, the rats were given a single injection with Ad-CTRP3 or Ad-GFP. The experiment was ended at 14th day after transfection.The serum levels of uric acid and nitric oxide （NO） were evaluated. The serum contents of TNF-α and interleukin-6 （IL-6） were measured by ELISA. HE staining and TUNEL assay were used to assess the morphological changes of intima and apoptosis of endothelial cells in thoracic aorta, respectively. The mRNA levels of endothelial nitric oxide synthase （eNOS）, TNF-α and IL-6 were detected by RT-qPCR. The protein levels of CTRP3 and Toll-like receptor 4 （TLR4） were determined by Western blot. RESULTS Compared with normal control group, the rats with hyperuricemia showed lower CTRP3 and higher TLR4 protein levels in the thoracic aorta （P<0.05）. Hyperuricemic rats had higher serum contents of uric acid, TNF-α and IL-6 （P<0.05）. Also, the intima structure disturbance of thoracic aorta, increased apoptotic rate, higher mRNA levels of TNF-α and IL-6 as well as lower mRNA levels of eNOS were observed （P<0.05）. By contrast, CTRP3 over-expression decreased TLR4 protein levels, reduced inflammatory cytokines, and obviously improved the morphology and function of thoracic aorta in the rats with hyperuricemia. CONCLUSION CTRP3 protect vascular endothelium in rats with hyperuricemia maybe via down-regulation of TLR4- mediated inflammatory signaling pathway.     

CYP450 epoxygenase/EET pathway attenuates adipose inflammation of obese mice through HIF-1α

AIM To investigate the effects of cytochrome P450 （CYP450） epoxygenase/epoxyeicosatrienoic acid （EET） pathway on insulin resistance in obese mice, and to explore the possible mechanisms. METHODS High-fat diet-induced obesity model was established in C57BL/6Cnc mice, and the obese mice were randomly divided into 3 groups, including obesity group （treated with saline; n=10）, EET group （treated with 11,12-EET; n=10） and EET inhibitor 14,15-epoxyeicosa-5（Z）-enoic acid （EEZE） group （n=10）. Normal C57BL/6Cnc mice （n=10） treated with saline served as control. Protein expression of CYP2J2 （one of CYP450 epoxygenases） and hypoxia-inducible factor-1α （HIF-1α） was measured by Western blot. Vessel-like structure was detected by immunofluorescence staining. The serum levels of insulin, tumor necrosis factor-α （TNF-α）, interleukin （IL）-1β, IL-6 and monocyte chemoattractant protein-1 （MCP-1） were measured by ELISA. RESULTS In obese mice, homeostasis model assessment of insulin resistance （HOMA-IR） values were increased, the protein level of CYP2J2 was reduced, and the protein level of HIF-1α was increased in adipose tissues as compared with the controls （P<0.05）. The serum levels of MCP-1, IL-1β, IL-6 and TNF-α were also significantly increased in obese mice （P<0.05）. After treatment with 11, 12-EET, the HOMA-IR values were decreased compared with vehicle-treated obese mice, HIF-1α expression levels were decreased in the adipose tissue, and the serum levels of MCP-1, IL-1β, IL-6 and TNF-α were reduced （P<0.05）. Immunohistochemical results of adipose tissue from vehicle-treated obese mice showed a marked decrease in vessel-like structures （CD31-positive） compared with normal control mice （P<0.05）. EET treatment significantly increased the newly formed vessel-like structures in the visceral adipose tissues of obese mice as compared with vehicle-treated obese mice （P<0.05）. CONCLUSION High-fat diet-induced obesity and insulin resistance are closely related to the CYP450 pathway. Exogenous EETs effectively decrease obesity-induced insulin resistance possibly through pro-angiogenesis and attenuation of hypoxia and inflammation.     

Rapamycin promotes repair of neurovascular units after ischemic stroke

Neurovascular unit （NVU） is composed of neurons, endothelial cells, pericytes, astrocytes, macrophages/microglia, smooth muscle cells, extracellular matrix, etc, and plays vital roles in maintenance of the normal brain tissue function and cellular homeostasis. Cerebral ischemia caused by stroke can harm various components of NVU. Repairing damaged NVU and maintaining its structural and functional integrity are an effective way to improve stroke treatment. Resent research has found that rapamycin not only enhances autophagy of neurons but also effectively repairs the injuried components of NVU , thereby reducing neural damage after stroke. In this paper, the mechanisms of rapamycin underlying the repair of injured NVU after ischemic stroke is reviewed to provide guidance for its application in the treatment of stroke.