Spinal NF-κB and chemokine ligand 5 expression during spinal glial cell activation in a neuropathic pain model.

BACKGROUND: The NF-κB pathway and chemokine (C-C motif) ligand 5 (CCL5) are involved in pain modulation; however, the precise mechanisms of their interactions in chronic neuropathic pain have yet to be established. METHODS: The present study examined the roles of spinal NF-κB and CCL5 in a neuropathic pain model after chronic constriction injury (CCI) surgery. CCI-induced pain facilitation was evaluated using the Plantar and von Frey tests. The changes in NF-κB and CCL5 expression were analyzed by immunohistochemistry and Western blot analyses. RESULTS: Spinal NF-κB and CCL5 expression increased after CCI surgery. Repeated intrathecal infusions of pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor) decreased CCL5 expression, inhibited the activation of microglia and astrocytes, and attenuated CCI-induced allodynia and hyperalgesia. Intrathecal injection of a CCL5-neutralizing antibody attenuated CCI-induced pain facilitation and also suppressed spinal glial cell activation after CCI surgery. However, the CCL5-neutralizing antibody did not affect NF-κB expression. Furthermore, selective glial inhibitors, minocycline and fluorocitrate, attenuated the hyperalgesia induced by intrathecal CCL5. CONCLUSIONS: The inhibition of spinal CCL5 expression may provide a new method to prevent and treat nerve injury-induced neuropathic pain.

Resveratrol attenuates bone cancer pain through the inhibition of spinal glial activation and CX3CR1 upregulation.

The present study examined the effects of intrathecal use of resveratrol on pain hypersensitivities, spinal glia activation, and CX3CR1 expression in the model of bone cancer pain (BCP). The BCP model was established through intrathecally injecting Walker 256 mammary gland carcinoma cells to Sprague-Dawley rats. We found that spinal CX3CR1 expression and glial activation aggravated after inoculation. Resveratrol (i.t.) attenuated bone cancer-induced pain hypersensitivities, decreased CX3CR1 expression and glial activation in the spine in a BCP model. Resveratrol (i.t.) also attenuated mechanical allodynia resulting from intrathecally injecting fractalkine in rats. Inhibition of spinal glial activation and CX3CR1 upregulation may involve in resveratrol's analgesic effects. These findings demonstrated that resveratrol attenuated pain facilitation through inhibiting spinal glial activation and CX3CR1 upregulation in a BCP model.

Prevention of cardiac events caused by surgical stress in aged rats: simultaneously activating ß2-adrenoceptor and inhibiting ß1-adrenoceptor.

Increased plasma catecholamine levels are associated with a high risk of perioperative cardiac events in aged individuals undergoing non-cardiac surgical interventions. Given the different effects of ß1-adrenoreceptor (ß1AR) and ß2-adrenoreceptor (ß2AR) stimulation by catecholamine in cardiomyocytes, this study evaluated whether simultaneous inhibition of ß1AR and activation of ß2AR is better than separate application in reducing the risk of perioperative cardiac events in aged rats undergoing non-cardiac surgery. Male aged Sprague-Dawley (SD) rats were divided into five groups. Normal group received no treatment. Surgery group received an abdominal surgery with hypoxia. ß1- group, ß2+ group, ß2+ group and ß1+ß2+ group received surgery and hypoxia with metoprolol (100 mg/kg·d), fenoterol (250 µg/kg·d) or both, respectively. The drugs were given three days before surgery with treatment continued through post-surgical day 7. The results showed that simultaneous activation of ß2AR with a ß2AR agonist and inhibition of ß1AR with a selective ß1AR blocker normalized myocardial oxygen consumption, decreased myocardial damage, augmented cardiomyocyte survival, improved cardiac function, reduced the incidence of arrhythmia, thus decreasing the occurrence of cardiac events in perioperative aged rats undergoing non-cardiac surgery. The results demonstrated that combined use of ß2AR agonist and ß1AR blocker achieved better general effects than use of either one alone. Our results provide a new insight into preventing perioperative cardiac events for elderly patients undergoing surgical stress.

Protective effect of endogenous hydrogen sulfide against oxidative stress in gastric ischemia-reperfusion injury.

Hydrogen sulfide (H(2)S) is a gaseous signaling molecule, which plays a critical role in a number of physiological and pathological progresses. In order to determine the effect of endogenous H(2)S on gastric ischemia-reperfusion (GI-R), we evaluated the gastric mucosal damage in rats intraperitoneally injected with DL-propargylglycine (PAG, 50 mg/kg/day) or L-cysteine (L-cys, 50 mg/kg/day) for 7 days before GI-R. GI-R injury was achieved by clamping the celiac artery for 30 min, followed by reperfusion for 60 min. Gastric mucosal damage was macroscopically assessed in the area of injury and deep damage was assessed by histopathological scoring. PAG increased the area of gastric mucosal injury and deep damage compared with that in untreated GI-R rats (P<0.05). While PAG decreased the H(2)S concentration and cystathionine γ-lyase (CSE) expression in the gastric mucosa, L-cys significantly attenuated the effects of GI-R. Western blot analysis revealed that the increases of malondialdehyde (MDA) and xanthine oxidase (XOD), and decreases of glutathione (GSH), superoxide dismutase (SOD) and the restriction of superoxide (O(2) (-)) production in the PAG group were inhibited by L-cys (P<0.05). Endogenous H(2)S has a protective effect against GI-R in rats by inhibiting oxygen free radical overproduction.

Resveratrol facilitates pain attenuation in a rat model of neuropathic pain through the activation of spinal Sirt1.

BACKGROUND: Little research has been conducted regarding the implications of Sirt1 (a classic III HDAC) in neuropathic pain. The aim of this study was to investigate the variation in the expressions of spinal Sirt1 and acetyl-histone H3 in a rat model of chronic constriction injury. METHODS: A neuropathic pain model of chronic constriction injury (CCI) was established in a unilateral hind limb in Sprague-Dawley rats. RESULTS: Western blot analysis and immunohistochemistry revealed that Sirt1 (silent information regulator) expression decreased, whereas acetyl-histone H3 increased in the spinal cord following CCI surgery. The intrathecal administration of resveratrol, an activator of Sirt1, attenuated CCI-induced mechanical allodynia and thermal hyperalgesia, increased Sirt1 expression, and decreased acetyl-histone H3 in the spine. Resveratrol induced no obvious histopathological changes in the spinal cord. CONCLUSIONS: Our data provide new evidence for the contribution of spinal Sirt1 to the initiation and maintenance of neuropathic pain. The antinociceptive effects of resveratrol may be mediated through the activation of spinal Sirt1 in CCI rats.

Oxidative stress induces gastric submucosal arteriolar dysfunction in the elderly.

AIM: To evaluate human gastric submucosal vascular dysfunction and its mechanism during the aging process. METHODS: Twenty male patients undergoing subtotal gastrectomy were enrolled in this study. Young and elderly patient groups aged 25-40 years and 60-85 years, respectively, were included. Inclusion criteria were: no clinical evidence of cardiovascular, renal or diabetic diseases. Conventional clinical examinations were carried out. After surgery, gastric submucosal arteries were immediately dissected free of fat and connective tissue. Vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were measured by isolated vascular perfusion. Morphological changes in the gastric mucosal vessels were observed by hematoxylin and eosin (HE) staining and Verhoeff van Gieson (EVG) staining. The expression of xanthine oxidase (XO) and manganese-superoxide dismutase (Mn-SOD) was assessed by Western blotting analysis. The malondialdehyde (MDA) and hydrogen peroxide (H2O2) content and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined according to commercial kits. RESULTS: The overall structure of vessel walls was shown by HE and EVG staining, respectively. Disruption of the internal elastic lamina or neointimal layers was not observed in vessels from young or elderly patients; however, cell layer number in the vessel wall increased significantly in the elderly group. Compared with submucosal arteries in young patients, the amount of vascular collagen fibers, lumen diameter and media cross-sectional area were significantly increased in elderly patients. Ach- and SNP-induced vasodilatation in elderly arterioles was significantly decreased compared with that of gastric submucosal arterioles from young patients. Compared with the young group, the expression of XO and the contents of MDA and H2O2 in gastric submucosal arterioles were increased in the elderly group. In addition, the expression of Mn-SOD and the activities of SOD and GSH-Px in the elderly group decreased significantly compared with those in the young group. CONCLUSION: Gastric vascular dysfunction and senescence may be associated with increased oxidative stress and decreased antioxidative defense in the aging process.

Chronic activation of the G protein-coupled receptor 30 with agonist G-1 attenuates heart failure.

G protein-coupled receptor (GPR) 30 is a novel estrogen receptor. Recent studies suggest that activation of the GPR30 confers rapid cardioprotection in isolated rat heart. It is unknown whether chronic activation of GPR30 is beneficial or not for heart failure. In this study we investigated the cardiac effect of sustained activation or inhibition of GPR30. Female Sprague-Dawley rats were divided into 7 groups #2Q1: sham surgery (Sham), bilateral ovariectomy (OVX), OVX+estrogen (E(2)), OVX+isoproterenol (ISO), OVX+ISO+G-1, OVX+ISO+E(2)+G15, OVX+ISO+E(2). ISO (85 mg/kg×17 day, sc) was given to make the heart failure models. G-1(120 µg/kg·d×14 day) was used to activate GPR30 and G15 (190 µg/kg·d×14 day) was used to inhibit GPR30. Concentration of brain natriuretic peptide in serum, masson staining in isolated heart, contractile function and the expression of ß(1) and ß(2)- adrenergic receptor (AR) of ventricular myocytes were also determined. Our data showed that ISO treatment led to heart failure in OVX rats. G-1 or E(2) treatment decreased concentration of brain natriuretic peptide, reduced cardiac fibrosis, and enhanced contraction of the heart. Combined treatment with ß(1) (CGP20712A) and ß(2)-AR (ICI118551) antagonist abolished the improvement of myocardial function induced by G-1. We also found that chronic treatment with G-1 normalized the expression of ß(1)-AR and increased the expression of ß(2)-AR. Our results indicate that chronic activation of the GPR30 with its agonist G-1 attenuates heart failure by normalizing the expression of ß(1)-AR and increasing the expression of ß(2)-AR.

H(2)S-releasing aspirin protects against aspirin-induced gastric injury via reducing oxidative stress.

The aim of this study was to examine the effect of ACS14, a hydrogen sulfide (H(2)S)-releasing derivative of aspirin (Asp), on Asp-induced gastric injury. Gastric hemorrhagic lesions were induced by intragastric administration of Asp (200 mg/kg, suspended in 0.5% carboxymethyl cellulose solutions) in a volume of 1 ml/100 g body weight. ACS14 (1, 5 or 10 mg/kg) was given 30 min before the Asp administration. The total area of gastric erosions, H(2)S concentration and oxidative stress in gastric tissues were measured three hours after administration of Asp. Treatment with Asp (200 mg/kg), but not ACS14 (430 mg/kg, at equimolar doses to 200 mg/kg Asp), for 3 h significantly increased gastric mucosal injury. The damage caused by Asp was reversed by ACS14 at 1-10 mg/kg in a concentration-dependent manner. ACS14 abrogated Asp-induced upregulation of COX-2 expression, but had no effect on the reduced PGE(2) level. ACS14 reversed the decreased H(2)S concentrations and blood flow in the gastric tissue in Asp-treated rats. Moreover, ACS14 attenuated Asp-suppressed superoxide dismutase-1 (SOD-1) expression and GSH activity, suggesting that ACS14 may stimulate antioxidants in the gastric tissue. ACS14 also obviously inhibited Asp-induced upregulation of protein expression of oxidases including XOD, p47(phox) and p67(phox). In conclusion, ACS14 protects Asp induced gastric mucosal injury by inhibiting oxidative stress in the gastric tissue.

ß2-adrenoceptor transfection enhances contractile reserve of isolated rat ventricular myocytes exposed to chronic isoprenaline stimulation by improving ß1-adrenoceptor responsiveness.

CONTEXT: Heart failure (HF) is a progressive deterioration in heart function associated with overactivity of the sympathetic nervous system. Elevated sympathetic nervous system activity down regulates the ß-adrenergic signal system, suppressing ß-adrenoceptors (ß-ARs)-mediated contractile support in the failing heart. OBJECTIVE: We investigated the effects of ß(2)-AR gene transfer on shortening amplitude of isolated ventricular myocytes under chronic exposure to isoprenaline (ISO), and further determine the contributions of ß(1)-AR and ß(2)-AR to the contraction. MATERIALS AND METHODS: Cardiomyocytes were isolated from adult rat hearts and then transfected with ß(2)-AR gene using an adenovirus vector. Four hours after the infection, cardiomyocytes were treated with ISO for another 24 hours to imitate high levels of circulating catecholamines in HF. Western blotting was performed to measure myocardial protein expression of ß(2)-AR. Video-based edge-detection system was used to evaluate basal and ISO-stimulated shortening amplitudes of cardiomyocytes. RESULTS: ß(2)-AR gene transfer increased ß(2)-AR protein content. Chronic ISO stimulation produced a negative inotropic response, whereas acute ISO stimulation showed a positive inotropic response. ß(2)-AR gene transfer had no significant effects on shortening amplitude of cardiomyocytes under normal conditions, but enhanced the blunted contraction of cardiomyocytes under pathological conditions induced by chronic ISO stimulation, and the effect was inhibited by ß(1)-AR antagonist, CGP 20712A, instead of ß(2)-AR antagonist, ICI 118,551. DISCUSSION AND CONCLUSIONS: We conclude that ß(2)-AR gene transfer in isolated ventricular myocytes under chronic ISO stimulation improves cellular contraction, and the beneficial effects might be mediated by improving ß(1)-adrenoceptor responsiveness.

Testosterone enhances estradiol's cardioprotection in ovariectomized rats.

After menopause, the development of cardiovascular disease (CVD) is due not only to estrogen decline but also to androgen decline. This study examined the effects of either estradiol (E(2)) or testosterone replacement alone or E(2)-testosterone combination on isolated myocytes in ovariectomized (Ovx) rats subjected to ischemia/reperfusion (I/R). Furthermore, we determined whether the effects are associated with ß(2)-adrenoceptor (ß(2)-AR). Five groups of adult female Sprague-Dawley rats were used: Sham operation (Sham) rats, bilateral Ovx rats, Ovx rats with E(2) 40 µg/kg per day (Ovx+E), Ovx rats with testosterone 150 µg/kg per day (Ovx+T), and Ovx rats with E(2) 40 µg/kg per day+testosterone 150 µg/kg per day (Ovx+E/T). We determined the lactate dehydrogenase (LDH) release, percentage of rod-shaped cells and apoptosis of ventricular myocytes from rats of all groups subjected to I/R. Then, we determined the above indices and contractile function with or without a selective ß(2)-AR antagonist ICI 118 551. We also determined the expression of ß(2)-AR. Our data show that either E(2) or testosterone replacement alone or E(2) and testosterone in combination decreased the LDH release, increased the percentage of rod-shaped cells, reduced apoptotic cells (%), and combination treatment appeared to be more effective than either E(2) or testosterone replacement alone. ICI 118 551 abolished the effects of the three. Combination supplementation also enhanced the expression of ß(2)-AR. We concluded that in Ovx rats, testosterone enhances E(2)'s cardioprotection, while E(2) and testosterone in combination was more effective and the protective effects may be associated with ß(2)-AR. The study highlights the potential therapeutic application for CVD in postmenopausal women.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats.

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation. METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in Sprague-Dawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice. RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased in the early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05). CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.

Hydrogen sulfide: a novel signaling molecule in the vascular system.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter produced in mammalian cells. It is responsible for physiological functions in many organs and systems, with attention focused mainly on the cardiovascular and nervous systems. In the vascular system, H2S produces biphasic effects in regulation of vascular tone. At lower concentrations, it induces vasoconstriction predominantly via decreasing cyclic adenosine monophosphate in smooth muscle cell and inhibiting the production and bioavailability of nitric oxide. At higher concentrations, it produces vasorelaxation mainly through opening of KATP channels and induction of intracellular acidification. Scavenging reactive oxygen species and elevation of cyclic guanosine monophosphate are also implicated in the vasorelaxant response. This review presents an overview of the current knowledge of H2S in the vascular system, with special emphasis and discussion on the involvement of various signaling pathways and ion channels based on current understanding and reported literature till date.

beta2-Adrenoceptor confers cardioprotection against hypoxia in isolated ventricular myocytes and the effects depend on estrogenic environment.

Estrogen plays a cardioprotective role in female rat hearts subjected to ischemia/reperfusion injury. The its effects are, at least partially, associated with decreased cardiomyocyte contraction and increased expression of beta(2)-adrenoceptor (beta(2)-AR). We tested whether beta(2)-AR could be involved in cardioprotection against ischemic damage and whether the roles of beta(2)-AR were dependent on estrogenic environment. We first determined the effects of hypoxia/reoxygenation (H/R) on cardiomyocyte shortening in female rats. We then determined the roles of beta(2)-AR in cardiomyocyte shortening, lactate dehydrogenase (LDH) release in culture medium, and cell death during hypoxia in isolated myocytes from female rats. We further determined the effects of estrogen on the roles of beta(2)-AR during hypoxia. H/R induced short-term hibernation and stunning at the level of ventricular myocytes from normal female rats. Inhibition of beta(2)-AR with ICI118,551 significantly elevated adrenergic contractile reserve, myocardial injury, and cell death in normal female rats during hypoxia, whereas ovariectomy (OVX) prominently enhanced myocyte contraction, myocardial injury, and cell death, and deprived the alternations in normal female rats. These changes were restored to normal by estrogen replacement (OVX+E(2)). These data suggest that beta(2)-AR may be involved in the cardioprotection against ischemic damage, and the cardioprotection may depend on estrogenic environment.

Oestrogen changed cardiomyocyte contraction and beta-adrenoceptor expression in rat hearts subjected to ischaemia-reperfusion.

Women with functional ovaries have a lower cardiovascular risk than men and postmenopausal women. However, oestrogen replacement therapy remains controversial. This study examined the effect of ovarian hormone deficiency and oestrogen replacement on ventricular myocyte contractile function and expression of beta-adrenoceptors (beta-ARs). Female Sprague-Dawley rats were subjected to bilateral ovariectomy (OVX) or sham operation (Sham). A subgroup of OVX rats received oestrogen (E2) replacement (40 microg kg(-1) day(-1)) for 4 weeks. Cardiomyocyte shortening was evaluated in basal conditions and in the presence of isoprenaline (ISO). The expression of beta-ARs was assessed by Western blotting. The presence of lactate dehydrogenase (LDH) activity in the coronary effluent was determined. Ovariectomy promoted body weight gain associated with reduced serum E2 and uterine weight, all of which were abolished by treatment with E2. Ovariectomy increased the amplitude of both basal and ISO-stimulated contractions, increased LDH release, upregulated beta1-AR expression and downregulated beta2-AR expression, all of which were restored by treatment with E2. A beta1-AR antagonist, CGP20712A, but not a beta2-AR antagonist, ICI118,551, significantly decreased the amplitude of ventricular myocyte shortening. Oestrogen decreased cardiomyocyte contraction and the expression of beta1-AR, and increased expression of beta2-AR, and all these effects were abolished by the E2 receptor antagonist, ICI182,780. These data suggest that oestrogen plays a cardioprotective role in female rat hearts subjected to ischaemia-reperfusion injury, and the effects of oestrogen are associated with decreased cardiomyocyte contraction and expression of beta1-AR, and increased expression of beta2-AR.

Contribution of epoxyeicosatrienoic acids to flow-induced dilation in arteries of male ERalpha knockout mice: role of aromatase.

We studied the roles of estrogen receptors (ER) and aromatase in the mediation of flow-induced dilation (FID) in isolated arteries of male ERalpha-knockout (ERalpha-KO) and wild-type (WT) mice. FID was comparable between gracilis arteries of WT and ERalpha-KO mice. In WT arteries, inhibition of NO and prostaglandins eliminated FID. In ERalpha-KO arteries, N(omega)-nitro-L-arginine methyl ester (L-NAME) inhibited FID by approximately 26%, whereas indomethacin inhibited dilations by approximately 50%. The remaining portion of the dilation was abolished by additional administration of 6-(2-proparglyoxyphenyl)hexanoic acid (PPOH) or iberiotoxin, inhibitors of epoxyeicosatrienoic acid (EET) synthesis and large-conductance potassium channels, respectively. By using an electrophysiological technique, we found that, in the presence of 10 dyne/cm(2) shear stress, perfusate passing through donor vessels isolated from gracilis muscle of ERalpha-KO mice subjected to L-NAME and indomethacin elicited smooth muscle hyperpolarization and a dilator response of endothelium-denuded detector vessels. These responses were prevented by the presence of iberiotoxin in detector or PPOH in donor vessels. Gas chromatography-mass spectrometry (GC-MS) analysis indicated a significant increase in arterial production of EETs in ERalpha-KO compared with WT mice. Western blot analysis showed a significantly reduced endothelial nitric oxide synthase expression but enhanced expressions of aromatase and ERbeta in ERalpha-KO arteries. Treatment of ERalpha-KO arteries with specific aromatase short-interfering RNA for 72 h, knocked down the aromatase mRNA and protein associated with elimination of EET-mediation of FID. Thus, FID in male ERalpha-KO arteries is maintained via an endothelium-derived hyperpolarizing factor/EET-mediated mechanism compensating for reduced NO mediation due, at least in part, to estrogen aromatized from testosterone.

Increased superoxide leads to decreased flow-induced dilation in resistance arteries of Mn-SOD-deficient mice.

The role of mitochondrial manganese-superoxide dismutase (Mn-SOD) in the maintenance of vascular function has not yet been studied. Thus we examined flow- and agonist-induced dilations in isolated mesenteric arteries (approximately 90 microm in diameter) of Mn-SOD heterozygous (Mn-SOD+/-) and wild-type (WT) mice. Increases in flow elicited dilations in all vessels, but the magnitude of the dilation was significantly less in vessels of Mn-SOD+/- mice than in those of WT mice (64 vs. 74% of passive diameter). N(omega)-nitro-L-arginine methyl ester inhibited the dilation in vessels of WT mice but had no effect on vessels of Mn-SOD+/- mice. Tempol or tiron (superoxide scavengers) increased flow-induced dilation in vessels of Mn-SOD+/- mice. Acetylcholine- and sodium nitroprusside-induced, but not adenosine-induced, dilations were also decreased in arteries of Mn-SOD+/- mice. Superoxide levels in the arteries of Mn-SOD+/- mice were significantly increased. Western blot analysis confirmed a 50% reduction of Mn-SOD protein in the vessels of Mn-SOD+/- mice. A 41% reduction in endothelial nitric oxide synthase (eNOS) protein and a 37% reduction in eNOS activity were also found in the vessels of Mn-SOD+/- mice. Whereas there was no difference in eNOS protein in kidney homogenates of WT and Mn-SOD+/- mice, a significant reduction of nitric oxide synthase activity was found in Mn-SOD+/- mice, which could be restored by the administration of tiron. We conclude that an increased concentration of superoxide due to reduced activity of Mn-SOD, which inactivates nitric oxide and inhibits eNOS activity, contributes to the impaired vasodilator function of isolated mesenteric arteries of Mn-SOD+/- mice. These results suggest that Mn-SOD contributes significantly to the regulation of vascular function.

Estrogen elicits cytochrome P450--mediated flow-induced dilation of arterioles in NO deficiency: role of PI3K-Akt phosphorylation in genomic regulation.

This study investigated the mechanisms responsible for the estrogen-dependent, cytochrome P450 (CYP)-mediated dilator responses to shear stress in arterioles of NO-deficient female rats and mice. Flow-induced dilation (FID) was assessed in isolated arterioles from N(G)-nitro-L-arginine methyl ester (L-NAME)-treated male and ovariectomized female rats before and after overnight incubation with 17beta-estradiol (17beta-E2, 10(-9) mol/L). In control conditions, prostaglandins (PGs) mediated FID, because indomethacin (INDO) abolished the responses. After incubation of the vessels with 17beta-E2, the basal tone of arterioles was significantly reduced and FID was augmented. INDO did not affect the dilation of the vessels incubated with 17beta-E2. Dilations of these vessels, however, were eliminated by PPOH and miconazole, inhibitors of CYP/epoxygenase. Simultaneous incubation of the vessels with 17beta-E2 plus ICI, 182,780, an estrogen receptor antagonist, or wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K) phosphorylation or the transcriptional inhibitor DRB, prevented the reduced arteriolar tone and the enhanced CYP-mediated FID caused by incubation of vessels with 17beta-E2. Western blot analysis indicated a significantly increased phospho-Akt level in arterioles incubated with 17beta-E2 compared with those without 17beta-E2. The enhanced phospho-Akt in response to 17beta-E2 was localized, by immunohistochemistry, to arteriolar endothelial cells. Moreover, GC-MS analysis indicated a significantly increased production of epoxyeicosatrienoic acids, vasodilator metabolites of CYP/epoxygenase, in arterioles incubated with 17beta-E2, a response that was prevented by ICI 182780 and wortmannin, respectively. Thus, estrogen, via a receptor-dependent, PI3K/Akt-mediated pathway, transcriptionally upregulates CYP activity, leading to an enhanced arteriolar response to shear stress.

[C-fos expression within PVN and NTS of the rat induced by gastric ischemia/reperfusion injury].

AIM: To investigate the effect of paraventricular nucleus (PVN) stimulation and the c-fos expression within PVN and nucleus tractus solitarius (NTS) of the rat following gastric ischemia/reperfusion injury (GI/RI). METHODS: The rat celiac artery was clamped for thirty minutes and reperfused for sixty minutes, using Fos immunohistochemical method (ABC method) examined the c-fos expression within PVN and NTS. RESULTS: (1) Both electrical and chemical stimulation of the PVN obviously attenuated the GI/ RI. (2) Bilateral electrolytic lesion of NTS could eliminate the protective effect of electrical stimulation of the PVN. (3) The Fos-like immunoreactive neurons were increased in bilateral PVN and NTS by GI/RI. CONCLUSION: The function of PVN and NTS could be affected by the GI/RI noxious stimulation. PVN, NTS were involved in the regulation of GI/RI.