S-propargyl-cysteine delays the progression of atherosclerosis and increases eNOS phosphorylation in endothelial cells / 生理学报

The present study aimed to investigate the protective effect of S-propargyl-cysteine (SPRC) on atherosclerosis progression in mice. A mouse model of vulnerable atherosclerotic plaque was created in ApoE-/- mice by carotid artery tandem stenosis (TS) combined with a Western diet. Macrophotography, lipid profiles, and inflammatory markers were measured to evaluate the antiatherosclerotic effects of SPRC compared to atorvastatin as a control. Histopathological analysis was performed to assess the plaque stability. To explore the protective mechanism of SPRC, human umbilical vein endothelial cells (HUVECs) were cultured in vitro and challenged with oxidized low-density lipoprotein (ox-LDL). Cell viability was determined with a Cell Counting Kit-8 (CCK-8). Endothelial nitric oxide synthase (eNOS) phosphorylation and mRNA expression were detected by Western blot and RT-qPCR respectively. The results showed that the lesion area quantified by en face photographs of the aortic arch and carotid artery was significantly less, plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were reduced, plaque collagen content was increased and matrix metalloproteinase-9 (MMP-9) was decreased in 80 mg/kg per day SPRC-treated mice compared with model mice. These findings support the role of SPRC in plaque stabilization. In vitro studies revealed that 100 μmol/L SPRC increased the cell viability and the phosphorylation level of eNOS after ox-LDL challenge. These results suggest that SPRC delays the progression of atherosclerosis and enhances plaque stability. The protective effect may be at least partially related to the increased phosphorylation of eNOS in endothelial cells.

Histone deacetylase 6 promotes skin wound healing by regulating fibroblast migration and differentiation in aged mice / 生理学报

Skin wound healing tends to slow down with aging, which is detrimental to both minor wound recovery in daily life and the recovery after surgery. The aim of current study was to explore the effect of histone deacetylase 6 (HDAC6) on wound healing during aging. Cultured human dermal fibroblasts (HDFs) and mouse full-thickness skin wound model were used to explore the functional changes of replicative senescent dermal fibroblasts and the effect of aging on skin wound healing. Scratch wound healing assay revealed significantly decreased migration speed of senescent HDFs, and BrdU incorporation assay indicated their considerably retardant proliferation. The protein expression levels of collagen and HDAC6 were significantly decreased in both senescent HDFs and skin tissues from aged mice. HDAC6 activity inhibition with highly selective inhibitor tubastatin A (TsA) or HDAC6 knockdown with siRNA decreased the migration speed of HDFs and considerably suppressed fibroblast differentiation induced by transforming growth factor-β1 (TGF-β1), which suggests the involvement of HDAC6 in regulating fundamental physiological activities of dermal fibroblasts. In vivo full-thickness skin wound healing was significantly delayed in young HDAC6 knockout mice when compared with young wild type mice. In addition, the wound healing was significantly slower in aged wild type mice than that in young wild type mice, and became even worse in aged HDAC6 knockout aged mice. Compared to the aged wild type mice, aged HDAC6 knockout mice exhibited delayed angiogenesis, reduced collagen synthesis, and decreased collagen deposition in skin wounds. Together, these results suggest that delayed skin wound healing in aged mice is associated with impaired fibroblast function. Adequate expression and activity of HDAC6 are required for fibroblasts migration and differentiation.

Central reactive oxygen species mediate cardiovascular effects of urotensin II in spontaneously hypertensive rats / 生理学报

Central urotensin II (UII) may participate in the regulation of cardiovascular functions by stimulating sympathy pathway. However, the central mechanism remained unknown. Recent studies have shown that brain reactive oxygen species (ROS) mediate the sympatho-excitatory effects. In the present study, we tested the hypothesis that ROS mediate central cardiovascular effects of UII. Experiments were conducted in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Immunocytochemistry, intracerebroventricular (icv) infusion and lucigenin-enhanced chemiluminescence assay were employed to detect UII receptor expression and ROS level, respectively. The following results were obtained: (1) Expressions of UII receptors of rostral ventrolateral medulla (RVLM) and nucleus tractus solitarii (NTS) were increased in SHR rats compared with WKY rats (P < 0.05). (2) UII (icv) significantly increased mean arterial pressure (MAP) (P < 0.05), and the effect of UII was significantly more pronounced in SHR rats than that in WKY rats (P < 0.05); (3) Tempol (a superoxide dismutase mimic) or Urantide (an antagonist of UII receptor) pretreatments eliminated the pressor effect of UII (P < 0.05) in SHR rats; (4) Brain superoxide level was increased in UII-treated SHR rats compared with that in cerebrospinal fluid (CSF)-treated SHR rats (P < 0.05). These results indicate that ROS mediate central cardiovascular effects of UII in SHR rats and provide evidence for a novel relationship between UII and ROS.

Involvement of HIF-1 in the migration-promoting effects of hydrogen sulfide in vascular endothelial cells under normoxic conditions / 生理学报

The purpose of this study was to investigate the molecular mechanisms whereby hydrogen sulfide (H2S) exerts the promoting effect on vascular endothelial cells migration. We used wound healing assay to study the effect of NaHS (H2S donor) on the migration ability of rhesus retinal pigment epithelial cell line, RF/6A cells, under normoxic conditions. Real-time PCR was used to measure hypoxia-inducible factor 1α (HIF-1α) mRNA level. Western blot was used to measure the expression of HIF-1α protein. The probe 2',7'-dichlorofluorescein diacetate (DCFH-DA) was used to measure intracellular reactive oxygen species (ROS) level. The results showed that NaHS (10-100 μmol/L) could significantly promote RF/6A cells migration under normoxic conditions, and this effect could be inhibited by 50 µmol/L HIF-1 inhibitor, CdCl2. NaHS increased the protein level of HIF-1α in a dose- and time-dependent manner, and up-regulated the mRNA level of HIF-1α quickly and continuously. Moreover, NaHS could significantly decrease ROS levels in RF/6A cells under normoxic conditions. These results suggest HIF-1 may mediate the promoting effect of H2S on vascular endothelial cells migration under normoxic conditions. ROS, as an upstream regulator of HIF-1α, may be involved in the migration-promoting effect of H2S.

Inhibitory effect of hydrogen sulfide on cardiac fibroblast proliferation / 生理学报

The aim of the present study was to investigate the role of hydrogen sulfide (H(2)S) in the proliferation of neonatal rat cardiac fibroblasts (NRCFs). Proliferation of NRCFs was induced by the presence of fetal bovine serum (FBS) or angiotensin II (Ang II) at various concentrations. The concentration-dependent effect of NaHS (donor of H(2)S) on NRCFs proliferation was examined. NRCFs proliferation was assessed by 5'-bromo-2'-deoxyuridine (BrdU) incorporation method. Reactive oxygen species (ROS) level was measured using the dye probe, 2', 7'-dichlorofluorescein diacetate (DCFH-DA). The results showed that FBS- or Ang II-induced NRCFs proliferations were inhibited with the treatment of relatively high concentrations of NaHS (5 × 10(-5) mol/L, 1 × 10(-4) mol/L), but FBS-induced proliferation was increased by low concentration of NaHS (1 × 10(-5) mol/L). Two or 6 h of Ang II (1 × 10(-7) mol/L) treatment caused an increase of ROS level in NRCFs, while this increase was inhibited with NaHS (1 × 10(-4) mol/L) treatment. These results suggest that H(2)S is an inhibitor of cardiac fibroblast at a certain concentration range. This inhibitory effect may be mediated by a reduction in intracellular ROS production.

Urotensin II inhibits glucokinase expression and glucose-induced insulin secretion / 生理学报

The purpose of the present study is to investigate the effects of urotensin II (UII) on insulin secretion in islet beta cells and the underlying mechanism. Glucose tolerance test was performed in Wistar rats to evaluate the effect of UII on the levels of plasma glucose and insulin. Static incubation experiment was employed to investigate the effect of UII on glucose-induced insulin secretion (GIIS) in betaTC-6 cells. After the incubation, insulin content and mRNA level in betaTC-6 cells were analyzed. Finally, Western blot was used to find out if UII could change the expression levels of pancreatic duodenal homeobox-1 (PDX-1) and glucokinase (GCK). It was observed that intravenous administration of UII (30, 300 nmol/kg) resulted in a significant decrease in insulin level 15 min after glucose load, and induced an obvious increase in plasma glucose 90 min after the load. In vitro, two hours of UII incubation inhibited GIIS in betaTC-6 cells without affecting insulin content and mRNA levels. The inhibitory effect of UII was blocked by UII receptor antagonist (urantide), and partially blunted by protein kinase C (PKC) inhibitor (chelerythrine) and somatostatin receptor antagonist (cyclosomatostatin). Moreover, we found that GCK protein level was significantly reduced by UII, while PDX-1, a key regulator of insulin gene transcription in beta cells, was not affected. These results suggest that UII-induced inhibition of GIIS in betaTC-6 cells are mediated by UII receptor and PKC pathway, as well as somatostatin receptor which could be activated by high dose of UII. The inhibitory effect of UII on insulin secretion is rather associated with a suppression of GCK expression than a regulation on PDX-1 expression.

Blockade of NMDA receptor enhances corticosterone-induced downregulation of brain-derived neurotrophic factor gene expression in the rat hippocampus through cAMP response element binding protein pathway / 生理学报

High concentration of corticosterone leads to morphological and functional impairments in hippocampus, ranging from a reversible atrophy of pyramidal CA3 apical dendrites to the impairment of long-term potentiation (LTP) and hippocampus-dependent learning and memory. Glutamate and N-methyl-D-aspartate (NMDA) receptor play an important role in this effect. Because of the importance of brain-derived neurotrophic factor (BDNF) in the functions of the hippocampal neurons, alteration of the expression of BDNF is thought to be involved in the corticosterone effect on the hippocampus. To determine whether change in BDNF in the hippocampus is involved in the corticosterone effect, we injected corticosterone (2 mg/kg, s.c.) to Sprague-Dawley rats and measured the mRNA, proBDNF and mature BDNF protein levels in the hippocampus. We also measured the phosphorylation level of the transcription factor cAMP response element binding protein (CREB). Furthermore, we intraperitoneally injected NMDA receptor antagonist MK801 (0.1 mg/kg) 30 min before corticosterone administration to investigate whether and how MK801 affected the regulation of BDNF gene expression by corticosterone. Our results showed that 3 h after single s.c. injection of corticsterone, the expression of BDNF mRNA, proBDNF and mature BDNF protein decreased significantly (P<0.01). MK801 promoted the downregulation of BDNF gene expression in the rat hippocampus by corticosterone. We also found that either applying corticosterone or co-applying corticosterone with MK801 downregulated the phosphoration level of CREB, the latter (corticosterone plus MK801) being more effective (P<0.05). Taken together, our results indicate that corticosterone downregulates BDNF gene expression in the rat hippocampus through CREB pathway and that blockade of NMDA receptor enhances this effect of corticosterone in reducing BDNF expression.

Endothelial cells and cardiac explants in three-dimensional culture system / 生理学报

To observe the morphological features of endothelial cells and cardiac explants cultured in two- or three-dimensional culture systems, several three-dimensional collagen type I culture systems, such as the in gel, on gel, sandwich model, and the microscope slide model, were used to examine the growth patterns of the cells and explants from heart by using immunofluorescence staining and microscopic observation in the presence or absence of vascular endothelial growth factor (VEGF). In two-dimensional cultures the primary cardiac endothelial cells arrayed into a cobblestone-like structure. When cultured in three-dimensional matrix, the cells were elongated and migrated into the gel, with a phenotype similar to that in the process of angiogenesis and vasculogenesis in vivo. VEGF promoted the process of the endothelial cells transforming into tube-like structure. Cardiac explants grew well in the collagen gel. Adjacent explants were connected to each other by the migrating cells with the occurrence of autorhythmic beating of the explants. Thin-layer collagen gel, microscope slide chamber and aorta-strip model were also tested and proved to be good tools for vasculogenesis or angiogenesis studies. Three-dimensional culture systems enable the endothelial cells to proliferate, migrate, and anchor to three-dimensional vascular structures, showing advantages for observing the feature of angiogenesis. Different three-dimensional culture models may be used for variable research purposes.

p38 Mitogen-activated protein kinase mediates hypoxia-induced vascular endothelial growth factor release in human endothelial cells / 生理学报

Increased vascular endothelial growth factor (VEGF) biosynthesis in vascular endothelial cells has been reported to play an obligatory role in promoting angiogenesis. Nevertheless, the intracellular signaling mechanisms of hypoxia-induced VEGF release remain largely unknown. Human umbilical vein endothelial cell lines (ECV304) were cultured in normoxic or hypoxic conditions for 12 approximately 24 h and harvested for determination of VEGF mRNA expression and phosphorylation of ERK1/2 and p38 mitogen-activated protein kinase (p38 MAPK) by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Secreted VEGF protein was measured by enzyme-linked immunosorbent assay (ELISA). It has reported that PD98059, an ERK inhibitor, was able to blunt the hypoxia-induced activation of the expression of VEGF gene. In accordance with this report, an increase in ERK1/2 phosphorylation and VEGF biosynthesis was observed in ECV304 cells cultured in hypoxia, and this increase was blocked by PD98059. The novel finding of the present study is that an activation of p38 MAPK is involved in hypoxia-induced increase in VEGF biosynthesis. SB202190, an inhibitor of p38 MAPK was able to blunt the hypoxia-induced increase in VEGF biosynthesis. These dada provide the first direct evidence for a role of p38 MAPK in mediating hypoxia-induced increase in VEGF biosynthesis in human endothelial cells.

Effect of angiotensin II on potassium channels of ischemic ventricular myocytes of the guinea pig / 生理学报

The experiments were carried out on guinea pig isolated ventricular myocytes by using whole-cell patch clamp. The effects of angiotensin II (Ang II) on potassium ion channels of acute ischemic myocytes were observed. Whole-cell patch clamp recordings showed that physiological potassium current, including delayed rectifier potassium current and inward rectifier potassium current were inhibited under the condition of simulated ischemia, and then further inhibited by treatment with Ang II. ATP-sensitive potassium currents were increased under simulated ischemia and were further enhanced by Ang II treatment.

Effect of angiotensin II on L-type calcium channel in ischemic ventricular myocytes of the guinea pig / 生理学报

Using whole cell patch clamp, the effects of angiotensin II (Ang II) on the current L-type calcium channel (I(Ca.L)) were observed in guinea pig isolated ventricular myocytes under simulated ischemia condition, which was realized through hypoxia, glucose deficiency, high lactic acid and acidosis. The results showed that, under the condition of simulated ischemia, the peak of I(Ca.L) was reduced with maximal activation potential at 0 mV. Administration of Ang II (100 nmol/L) enhanced the peak of I(Ca.L) during ischemia and shifted the maximal activation potential to -10 mV. The possible mechanism of these effects is discussed.