Exogenous hydrogen sulfide reduces vascular aging in D-galactose-induced subacute aging rats / 生理学报

The present study was aimed to observe the protective effect of exogenous hydrogen sulfide (H₂S) on vascular structural and functional changes of aorta in D-galactose-induced subacute aging rats. Adult male SD rats were randomly divided to five groups: the vehicle group, the D-galactose (D-gal) group, and the three NaHS groups treated with low (1 μmol·kg⁻¹·d⁻¹), middle (10 μmol·kg⁻¹·d⁻¹) or high (100 μmol·kg⁻¹·d⁻¹) dose of NaHS respectively. The D-gal group rats were given subcutaneously injection of 125 mg/kg D-gal per day for eight weeks to induce subacute aging model. In the NaHS group, D-gal was administered as above but with NaHS intraperitoneally injected at a dosage of 1, 10, 100 μmol·kg⁻¹·d⁻¹ respectively. Equivalent volumes of saline were administered per day for eight weeks in vehicle group. Morphological changes of aorta were observed by HE and Masson staining. The level of H₂S in serum, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA), as well as anti-superoxide anions in vascular tissue were determined by spectrophotometry. Angiotensin II (AngII) levels in plasma were measured using competitive enzyme immunoassay. The expression of angiotensin II type 1 receptor (AT1R) in aorta was determined by Western blot. The results showed that the aging aortic morphologic changes in model rats were ameliorated in NaHS groups. Decreased vascular endothelial exfoliative cells and vascular smooth muscle cell (SMC) proliferation were shown in NaHS groups by HE staining. Masson staining analysis showed reduced relative contents of collagen fibers (P < 0.05) and SMC (P < 0.05) in NaHS groups. Compared to vehicle group, serum concentration of H₂S in D-gal group was decreased, while it was increased in NaHS groups after treatment with NaHS (P < 0.05). In the D-gal group, the concentration of AngII in plasma was significantly increased compared with that in vehicle group, while it was decreased in NaHS groups (P < 0.05). Moreover, levels of vascular tissue anti-superoxide anion and the activity of SOD were obviously higher, MDA was significantly lower in all NaHS treated groups than those in the D-gal group respectively (P < 0.05). Western blot analysis showed that the expression of AT1R was increased in D-gal group compared with that in vehicle group, while it was decreased after treatment with NaHS compared with that in D-gal group (P < 0.05). These results suggest that exogenous H₂S can ameliorate the age-related changes of aortic morphology, decrease the concentration of AngII in plasma, down-regulate the expression of AT1R in vascular tissue, and mitigate the level of oxidative stress. These changes delay the vascular aging in aging rats ultimately.

Danshensu delays the senescence of rat aortic endothelial cells via activation of SIRT1-SOD pathway / 生理学报

The present study was aimed to investigate the effect of pretreatment with Danshensu (DSS) on rat aortic endothelial cells (RAECs) senescence and the underlying mechanisms. Cultured RAECs at fourth and twelfth passages were taken as young and old groups, respectively. DSS and DSS+nicotinamide (DSS+N) groups were incubated with DSS and DSS in combination with nicotinamide, an inhibitor of silent information regulator 1 (SIRT1), from the fourth to twelfth passage, respectively. The cell status of senescence was determined by the senescence-associated β-galactosidase (SA β-gal) staining, and 4,6-diamino-2-phenyl indole (DAPI) fluorescent dye was used to detect senescence associated heterochromatin foci (SAHF) formation; Thiobarbituric acid (TBA) and colorimetric methods were used to evaluate malondialdehyde (MDA) and H₂O₂contents; Western blot was employed to analysis the expressions of xanthine oxidase (XOD), SIRT1 and superoxide dismutase 2 (SOD₂) in the RAECs. The results showed that, in comparison with young group, the old group exhibited higher SA β-gal positive and SAHF formation rates, as well as higher MDA and H₂O₂levels (P < 0.05 or P < 0.01), whereas DSS pretreatment reduced SA β-gal positive and SAHF formation rates, decreased MDA and H2O2 contents (P < 0.05 or P < 0.01). The protection of DSS was reversed by nicotinamide. Compared with the young group, the old group showed higher expression levels of XOD, but lower SIRT1 and SOD₂expression levels (P < 0.05 or P < 0.01). With the pretreatment of DSS, the expression of XOD was declined, and the expression levels of SIRT1 and SOD₂were elevated, while nicotinamide reversed the effects of DSS. These results suggest that DSS delays senescence of RAECs via up-regulation of SIRT1.

Exogenous hydrogen sulfide attenuates gastric ischemia-reperfusion injury via activation of K(ATP) channel / 生理学报

The present study aimed to investigate the protective effect and mechanism of hydrogen sulfide donor NaHS administration against gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) in rats. GI-R injury was induced by clamping the celiac artery of adult male SD rats for 30 min and followed by reperfusion for 1 h. The rats were randomly divided into sham group, GI-R group, NaHS group, glibenclamide group and pinacidil group. Gastric mucosal damage was analyzed with macroscopic injured area, deep damage was assessed with histopathology scores, and the hydrogen sulfide concentration in plasma was determined by colorimetric method. The results showed that pretreatment of NaHS significantly reduced the injured area and deep damage of the gastric mucosa induced by GI-R. However, NaHS did not significantly alter the levels of hydrogen sulfide in plasma 14 d after NaHS administration. The gastric protective effect of NaHS during reperfusion could be attenuated by glibenclamide, an ATP-sensitive potassium channel (K(ATP)) blocker. However, K(ATP) opener pinacidil inhibited the GI-R-induced injury. These results suggest that exogenous hydrogen sulfide plays a protective role against GI-R injury in rats possibly through modulation of K(ATP) channel opening.

Exogenous hydrogen sulfide delays the senescence of human umbilical vein endothelial cells by lessening oxidative stress / 生理学报

The present study was aimed to investigate the effect of pretreatment with hydrogen sulfide (H2S) on human umbilical vein endothelial cells (HUVECs) senescence and the underlying mechanism. Cultured HUVECs at twelfth and fourth passages were taken as old and young groups, respectively. Sodium hydrosulfide (NaHS, donor of H2S) group was treated with NaHS from fourth to twelfth passage. The cell senescence was determined by senescence-associated β-galactosidase (SA β-gal) staining. DAPI fluorescent dye was used to detect cellular apoptosis. Western blot was used to analyze the expression levels of xanthine oxidase (XOD), manganese-superoxide dismutase (Mn-SOD) and the subunits p67(phox) of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the HUVECs. Colorimetric method was used to detect SOD activity and cellular hydrogen peroxide (H2O2) level. The results showed that, compared with young group, the old group exhibited higher SA β-gal positive rate and cellular apoptosis, while NaHS pretreatment decreased SA β-gal positive rate and cellular apoptosis. Compared with the young group, the old group showed increased expression levels of XOD and p67(phox), as well as lower Mn-SOD expression level. With the pretreatment of NaHS, the up-regulations of XOD and p67(phox) levels and down-regulation of Mn-SOD level were inhibited. Compared with the young group, the old group showed lower SOD activity and higher H2O2 level, whereas NaHS pretreatment reversed the changes of SOD activity and H2O2 level. These results suggest that H2S delays senescence of HUVECs through lessening oxidative stress.

C-fos expression within PVN and NTS of the rat induced by gastric ischemia/reperfusion injury / 中国应用生理学杂志

<p><b>AIM</b>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).</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>(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.</p><p><b>CONCLUSION</b>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.</p>

Capsaicin-sensitive afferent fibers and endogenous NO mediate the gastric acid secretion and gastric mucosal blood flow in intragastric distention in rats / 中国应用生理学杂志

<p><b>AIM AND METHODS</b>By hydrogen gas clearance technique to measure gastric mucosal blood flow (GMBF) and a high dose of capsaicin to ablate the capsaicin-sensitive afferent fibers, the roles of capsaicin-sensitive afferent fibers and endogenous NO in the gastric acid secretion and hyperemic response to intragastric distention were studied in rats.</p><p><b>RESULTS</b>(1) There was an increase in acid secretion associated with the increase in GMBF to intragastric distention. (2) Pretreatment with a high dose of capsaicin to ablate afferent fibers completely abolished the GMBF and partially inhibited the acid secretion during the intragastric distention. (3) The increase in GMBF to intragastric distention was completely blocked by pretreatment with L-NAME, whereas the acid secretion was significantly attenuated.</p><p><b>CONCLUSION</b>Capsaicin-sensitive afferent fibers and endogenous NO are involved in the increases of gastric acid secretion and GMBF.</p>

The effects of neuropeptides on the regulations of gastric mucosal blood flow in central nervous system and periphery in rats / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of calcitonin gene-related peptide (CGRP), gastrin 17 (G17), bombesin (Bom), met-enkephalin (Met-enk), neuropeptide Y (NPY) and somatostatin (SS) on GMBF and the role of endogenous NO in increased GMBF induced by neuropeptides in rats.</p><p><b>METHODS</b>By hydrogen gas clearance technique to measure gastric mucosal blood flow (GMBF) and arterial infusion close to stomach or intracerebroventricular (icv) to microinject neuropeptides.</p><p><b>RESULTS</b>(1) Arterial infusions of CGRP and G17 (5, 50 and 100 pmol x min(-1)) increased GMBF significantly in dose-dependent manners. CGRP had more effective effect on increasing GMBF than that of G17. Intravenous pretreatment of L-nitro-L-arginine methyl ester (L-NAME) to inhibit the synthesis of endogenous NO could abolish completely or partially the increases in GMBF response to CGRP or G17 respectively. (2) Arterial infusions of Bom and Met-enk (50 and 100 pmol x min(-1)) increased GMBF significantly. The increases in GMBF induced by Bom or Met-enk were abolished completely or partially by pretreatment of L-NAME respectively. (3) Arterial infusion of NPY (5, 50 and 100 pmol x min(-1)) led to reduction of GMBF significantly in a dose-dependent manner. SS (50 and 100 pmol x min(-1)) also reduced GMBF significantly. (4) icv microinjection of CGRP (10 microg) and G17 (10 Microg) increased GMBF significantly. The increases in GMBF induced by icv microinjection of CGRP or G17 were blocked completely or partially respectively by pretreatments with L-NAME. (5) icv microinjection of NPY (10 microg) decreased GMBF significantly.</p><p><b>CONCLUSION</b>Neuropeptides play important roles in the regulation of GMBF in rats and NO is involved in the increase of GMBF induced by some neuropeptides.</p>

Protective effects of paraventricular nucleus stimulation and vasopressin on gastric ischemia-reperfusion injury in rats / 生理学报

The effects of paraventricular nucleus (PVN) stimulation and vasopressin on gastric ischemia-reperfusion injury (GI-RI) were investigated in male SD rats of which the celiac artery was clamped for 30 min and reperfused for 1 h by removal of the clamp. The results were as follows. Both electrical and chemical stimulation of the PVN obviously attenuated the GI-RI. Bilateral electrolytic lesion of the nucleus tractus solitarius (NTS) or microinjection of AVP-V(1) receptor antagonist into the NTS could eliminate the protective effect of electrical stimulation of the PVN on GI-RI. Hypophysectomy did not influence the effect of electrical stimulation of the PVN. Both vagotomy and sympathectomy could increase the effect of stimulating PVN on GI-RI. Microinjection of arginine-vasopressin (AVP) into the PVN also attenuated the effect on GI-RI. These results suggest that the PVN and AVP participate in the regulation of GI-RI and play an important role in protection against GI-RI. This protective effect of PVN on GI-RI might be mediated by activation of AVP-ergic neurons in the PVN, which release AVP from the descending projection fibers and activate the AVP-V(1) receptors on the NTS neurons. The vagus and sympathetic nerves are involved in the efferent pathway exerting their effects on GI-RI. Hypophysis does not seem to be involved in the protective effect of PVN stimulation.

Effects of electrical stimulation of lateral hypothalamic area on gastric ischemia-reperfusion injury in rats / 生理学报

The effects of electrical and chemical stimulation and electrolytic lesion of lateral hypothalamic area (LHA) on gastric ischemia-reperfusion injury (GI-RI) were investigated in rats whose celiac arteries were clamped for 30 min and reperfused for 60 min by removal of the clamp. The results are as follows. (1) Electrical stimulation of LHA could aggravate GI-RI in an intensity-dependent manner by using 0.2, 0.4 or 0.6 mA current respectively. Microinjection of L-glutamic acid into LHA resulted in a similar effect to that of electrical stimulation of LHA on GI-RI. After electrolytic lesion of bilateral LHA, the area of gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) was smaller than that by electrical stimulation of LHA plus GI-R. (2) Dorsal vagal complex (DVC) lesion or vagotomy could eliminate the effect of electrical stimulation of LHA on GI-RI. (3) Electrical stimulation of LHA increased the content of malondialdehyde (MDA) but decreased the activity of superoxide dismutase (SOD) of ischemia-reperfusion (I-R) gastric mucosa. (4) Electrical stimulation of LHA plus gastric I-R increased gastric juice volume and total acid output, but there were no significant changes in acidity, pepsin activity and gastric barrier mucus. These results indicate that the LHA is an area in the CNS exerting aggravate effects on GI-RI. The DVC and vagus may be involved in the regulative effects of LHA on GI-RI. These effects are associated with increases in gastric mucosal MDA content, gastric juice volume, and total acid output, and a decrease in SOD activity.Acidity, pepsin activity and gastric barrier mucus do not seem to play an important role.