[Effects of Xiaotan Huayu Liqiao Formula on cognitive impairment in mice exposed to chronic intermittent hypoxia].

Objective: To investigate the improvement effects of Xiaotan Huayu Liqiao Formula on cognitive impairment in mice exposed to chronic intermittent hypoxia (CIH), and to explore the related mechanisms. Methods: Forty-eight male C57 BL/6 mice were randomly divided into four groups as Normoxia, CIH, Formula+CIH and Formula group. Mice were exposed to normoxia in the normoxia and formula group, or intermittent hypoxia in CIH or Formula+CIH group (in the chambers, mice were filled with 100% N2 to produce FiO2 of 9% for 1. 5 min. The FiO2 gradually returned to 21% over the remainder of each cycle. The exposure cycle was repeated every 3 min, 8 h/day for 35 days). Mice were treated with Xiaotan Huayu Liqiao Formula at the dose of 26. 8 g/kg by intragastric administration before CIH exposure. Meanwhile, mice in CIH and normoxia group were given the same volume of normal saline. When the experiment lasts for 26-35 d, Morris water maze was used to detect cognitive dysfunction in mice. At the end of 35 days, Y-maze was performed in each group. After anesthesia, hippocampus was isolated for morphological observation and Western blot ananlysis. Nissl staining and electron microscopy were adopted to assess the neuronal damage in hippocampus, and Western blot was used to detect the levels of PSD-95 and synapsin expression. Results: Compared with normoxia group,the performance of CIH mice was significantly reduced in Morris water maze and Y-maze(P＜0. 01,P＜0. 01). Both the number of Nissl staining positive cells and the thickness of the postsynaptic density in hippocampus were significantly reduced. And, the levels of PSD-95 expression in hippocampus was also decreased in the CIH group(P＜0. 01), however, no significant change of synapsin expression was observed. Compared to CIH group, administration of Xiaotan Huayu Liqiao Formula markedly improved performance of mice in Morris water maze and Y-maze (P＜0. 01), increased Nissl staining positive cells and the thickness of the postsynaptic density and PSD-95 expression in hippocampus (P＜0. 01). Conclusion: Xiaotan Huayu Liqiao Formula could alleviate the structural and functional impairment of the postsynaptic dense area, and improved CIH-induced cognitive dysfunction.

[The effects of Xiaotan Huayu Liqiao formula on mesenteric artery function in rats exposed to chronic intermittent hypoxia].

OBJECTIVE: To investigate the effects of Xiaotan Huayu Liqiao formula (the Chinese Medicine) on mesenteric artery function in rats exposed to chronic intermittent hypoxia (CIH), and to explore the related mechanism. METHODS: Forty-eight male SD rats were randomly divided into four groups as Normoxia, CIH, Formula+CIH and formula group. Rats were exposed to normoxia in the Normoxia and Formula group, or intermittent hypoxia in CIH or Formula+CIH group. Xiaotan Huayu Liqiao formula was given at 24g/kg by intragastric administration before intermittent hypoxia exposure. The pathological changes of mesenteric artery were determined by HE staining, and the relaxation of mesenteric artery (induced by acetylcholine(ACh) and L-arginine(L-Arg)) was recorded by microvascular ring technique. Serums of all rats were collected (0 d and 21 d) and the content of NO was detected by ELISA. The levels of endothelial nitric oxide synthase (eNOS) and p-eNOS were measured by Western blot. RESULTS: Compared with Normoxia group, the mesenteric arterial endothelial injury and media thickening were observed and the relaxation of mesenteric artery was significantly reduced in rats exposed to CIH. The level of NO in serum and the ratio of p-eNOS/eNOS were also decreased in the CIH group. Xiaotan Huayu Liqiao formula administration improved the pathologic changes and dilatation function of mesenteric artery, increased the levels of NO and p-eNOS. Compared with Normoxia group,all the results were not observed significant difference in Formula group. CONCLUSION: Xiaotan Huayu Liqiao formula increased the bioavailability of NO, and ameliorated the CIH induced mesenteric artery function injury.

Hydrogen protects against chronic intermittent hypoxia induced renal dysfunction by promoting autophagy and alleviating apoptosis.

AIMS: Hydrogen gas (H2) has a diversity of effects such as anti-apoptotic, anti-inflammatory and anti-oxidative properties. However, molecular mechanism underlying the potential effect of H2 on chronic intermittent hypoxia (CIH) induced renal injury remains obscure. MATERIALS AND METHODS: In the present study, adult male Sprague-Dawley rats were randomly allocated into four groups: control (CON) group, CIH group, CIH with H2 treatment (CIH + H2) group, and control with H2 treatment (CON + H2) group. Oxidative stress, autophagy and endoplasmic reticulum (ER) stress were detected to determine how H2 affected the renal function of CIH exposed rats. KEY FINDINGS: We demonstrated that rats who inhale hydrogen gas showed improved renal function, alleviated pathological damage, oxidative stress and apoptosis in CIH rats. Meanwhile, CIH-induced endoplasmic reticulum stress was decreased by H2 as the expressions of CHOP, caspase-12, and GRP78 were down-regulated. Furthermore, relative higher levels of LC3-II/I ratio and Beclin-1, with decreased expression of p62, were found after H2 administrated. Inhibition of mTOR may be involved in the upregulation of autophagy by H2. Finally, increased phosphorylation of p38 and JNK was involved in the CIH-induced pathological process. H2 could inhibit the activation of p38 and JNK, suggesting H2 played an active part in resisting renal injury via MAPK. SIGNIFICANCE: Taken together, our study reveals that H2 can ameliorate CIH-induced kidney injury by decreasing endoplasmic reticulum stress and activating autophagy through inhibiting oxidative stress-dependent p38 and JNK MAPK activation.

Hydrogen and Oxygen Mixture to Improve Cardiac Dysfunction and Myocardial Pathological Changes Induced by Intermittent Hypoxia in Rats.

Obstructive sleep apnea (OSA) can cause intermittent changes in blood oxygen saturation, resulting in the generation of many reactive oxygen species (ROS). To discover new antioxidants and clarify the endoplasmic reticulum (ER) stress involved in cardiac injury in OSA, we established a chronic intermittent hypoxia (CIH) rat model with a fraction of inspired O2 (FiO2) ranging from 21% to 9%, 20 times/h for 8 h/day, and the rats were treated with H2-O2 mixture (67% hydrogen and 33% oxygen) for 2 h/day for 35 days. Our results showed that H2-O2 mixture remarkably improved cardiac dysfunction and myocardial fibrosis. We found that H2-O2 mixture inhalation declined ER stress-induced apoptosis via three major response pathways: PERK-eIF2α-ATF4, IRE 1-XBP1, and ATF 6. Furthermore, we revealed that H2-O2 mixture blocked c-Jun N-terminal kinase- (JNK-) MAPK activation, increased the ratio of Bcl-2/Bax, and inhibited caspase 3 cleavage to protect against CIH-induced cardiac apoptosis. In addition, H2-O2 mixture considerably decreased ROS levels via upregulating superoxide dismutase (SOD) and glutathione (GSH) as well as downregulating NADPH oxidase (NOX 2) expression in the hearts of CIH rats. All the results demonstrated that H2-O2 mixture significantly reduced ER stress and apoptosis and that H2 might be an efficient antioxidant against the oxidative stress injury induced by CIH.

Hydrogen Gas Alleviates Chronic Intermittent Hypoxia-Induced Renal Injury through Reducing Iron Overload.

Iron-induced oxidative stress has been found to be a central player in the pathogenesis of kidney injury. Recent studies have indicated H2 can be used as a novel antioxidant to protect cells. The present study was designed to investigate the protective effects of H2 against chronic intermittent hypoxia (CIH)-induced renal injury and its correlation mechanism involved in iron metabolism. We found that CIH-induced renal iron overloaded along with increased apoptosis and oxidative stress. Iron accumulates mainly occurred in the proximal tubule epithelial cells of rats as showed by Perl's stain. Moreover, we found that CIH could promote renal transferrin receptor and divalent metal transporter-1 expression, inhibit ceruloplasmin expression. Renal injury, apoptosis and oxidative stress induced by CIH were strikingly attenuated in H2 treated rats. In conclusion, hydrogen may attenuate CIH-induced renal injury at least partially via inhibiting renal iron overload.

Hydrogen gas reduces chronic intermittent hypoxia-induced hypertension by inhibiting sympathetic nerve activity and increasing vasodilator responses via the antioxidation.

Molecular hydrogen is reported to be used medically to ameliorate various systemic pathological conditions. This study aimed to investigate the effect of hydrogen (H2 ) gas on hypertension induced by intermittent hypoxia in rats. The adult rats were exposed to chronic intermittent hypoxia (CIH) 8 hours/day for 5 weeks and/or H 2 gas 2 hours/day. We found that the systolic and diastolic blood pressure (BP) increased significantly in rats exposed to intermittent hypoxia, both of which were markedly attenuated after H treatment. Furthermore, intermittent hypoxia exposure elevated renal sympathetic nerve activity, consistent with plasma norepinephrine. Additionally, H 2 gas significantly improved CIH-induced abnormal vascular relaxation. Nevertheless, inhalation of H 2 gas alone did not cause such changes. Moreover, H 2 gas-treated rats exposed to CIH showed a significant reduction in 8-hydroxy-2 deoxyguanosine content and increases in superoxide dismutase activity, indicating improved oxidative stress. Taken together, these results indicate that H 2 gas has significant effects on the reduction of BP without any side effects. Mechanistically, inhibition of sympathetic activity and reduction of systemic vascular resistance may participate in this process via the antioxidant activity of H 2 .

Hydrogen ameliorates chronic intermittent hypoxia-induced neurocognitive impairment via inhibiting oxidative stress.

Obstructive sleep apnea (OSA) is a very common breathing and sleep disorder characterized by intermittent hypoxia (IH), which is often associated with behavioral and neurocognitive functions impairment. Hydrogen (H2), as a novel and effective antioxidant, is reported to be a potential neuroprotective agent. The aim of this study is to investigate whether H2 could improve CIH-induced neurocognitive impairment and the related mechanism. Rats were exposed to IH for 5 weeks (8 h/day) and/or inhalation of H2 gas 2 h/day. Morris Water Maze test was used to appraise the spatial reference and working memory. The oxidative stress was evaluated through the level of MDA and SOD and apoptosis of hippocampal neurons was assayed with Bcl-2/Bax ratio and TUNEL staining. Our results showed that H2 treatment improved the CIH-induced spatial learning and memory impairments. Moreover, inhalation of H2 gas reduced the level of MDA and increased in the activity of SOD, indicating suppressed CIH-induced oxidative stress. In addition, H2 could increase expression of Bcl-2/Bax ratio and inhibited neurons apoptosis in hippocampus. In conclusion, these results suggest that inhalation of H2 could attenuate the CIH-induced neurocognitive functions impairment via anti-oxidant and anti-apoptosis effect. Additional, our findings may provide a potential therapeutic for neurocognitive diseases in patients with OSA.

[Bosentan ameliorates hypertension in rats exposed to chronic intermittent hypoxia through inhibiting renal sympathetic nerve activity].

The purpose of this study is to investigate the effect of the oral endothelin antagonist Bosentan on blood pressure and renal sympathetic nerve activity (RSNA) in rats exposed to chronic intermittent hypoxia (CIH), and to explore the sympathoexcitation mechanism of endothelin-1 (ET-1) in CIH-induced hypertension. Twenty-four male SD rats were randomly divided into normoxia, CIH and Bosentan groups. Rats in the normoxia group were exposed to normoxic environment, and rats in CIH or Bosentan group were exposed to intermittent hypoxia for 3 weeks. Bosentan was given at 50 mg/kg by intragastric administration before intermittent hypoxia exposure in Bosentan group. Systolic blood pressure (SBP) was measured by BP-2000, and the change of RSNA to sodium nitroprusside (SNP) or phenylephrine (PE) was recorded by PowerLab signal acquisition system. Serums of all rats were collected and the contents of ET-1 and norepinephrine (NE) were measured by ELISA. Results showed that blood pressure was gradually increased following CIH exposure compared with the normoxia group during the 3 weeks (P < 0.01, P < 0.01, P < 0.001). The basal RSNA was increased and baroreflex sensitivity was decreased in rats exposed to CIH. Furthermore, the blood pressure was positively correlated with the level of ET-1 in serum in rats exposed to CIH (r = 0.833, P = 0.01). Bosentan administration significantly decreased SBP and basal RSNA, increased the baroreflex sensitivity, and decreased serum NE level in rats exposed to CIH. These results suggest that ET-1 is related with blood pressure elevation in rats exposed to CIH, and Bosentan reverses CIH-induced hypertension by decreasing RSNA.

[The role of adventitia in hypoxic vascular remodeling].

As an important site for the production, storage and release of key regulators for vascular function, the vascular adventitia is thought to be a damage sensing tissue in the vascular wall under certain conditions. The adventitial cells are usually the first ones to respond to vascular stress or injury, and consequently affect the structure and function of blood vessel wall. Growing lines of evidence have shown that the vascular adventitia exhibits the earliest and most prominent changes in vascular remodeling due to hypoxia and related pulmonary hypertension and atherosclerosis. In particular, fibroblasts play an important role in the adaptation and regulation to local microenvironmental changes. This review focuses on the role of vascular adventitia in hypoxia-induced vascular remodeling and the underlying molecular mechanisms.