Blockade of HCN2 Channels Provides Neuroprotection Against Ischemic Injury via Accelerating Autophagic Degradation in Hippocampal Neurons / 神经科学通报·英文版

In the central nervous system, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential to maintain normal neuronal function. Recent studies have shown that HCN channels may be involved in the pathological process of ischemic brain injury, but the mechanisms remain unclear. Autophagy is activated in cerebral ischemia, but its role in cell death/survival remains controversial. In this study, our results showed that the HCN channel blocker ZD7288 remarkably decreased the percentage of apoptotic neurons and corrected the excessive autophagy induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) in hippocampal HT22 neurons. Furthermore, in the OGD/R group, p-mTOR, p-ULK1 (Ser), and p62 were significantly decreased, while p-ULK1 (Ser), atg5, and beclin1 were remarkably increased. ZD7288 did not change the expression of p-ULK1 (Ser), ULK1 (Ser), p62, Beclin1, and atg5, which are involved in regulating autophagosome formation. Besides, we found that OGD/R induced a significant increase in Cathepsin D expression, but not LAMP-1. Treatment with ZD7288 at 10 μmol/L in the OGD/R group did not change the expression of cathepsin D and LAMP-1. However, chloroquine (CQ), which decreases autophagosome-lysosome fusion, eliminated the correction of excessive autophagy and neuroprotection by ZD7288. Besides, shRNA knockdown of HCN2 channels significantly reduced the accumulation of LC3-II and increased neuron survival in the OGD/R and transient global cerebral ischemia (TGCI) models, and CQ also eliminated the effects of HCN2-shRNA. Furthermore, we found that the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes decreased in Con-shRNA-transfected HT22 neurons exposed to OGD/R or CQ. In HCN2-shRNA-transfected HT22 neurons, the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes increased under OGD/R; however, the percentage was significantly decreased by the addition of CQ to HCN2-shRNA-transfected HT22 neurons. The present results demonstrated that blockade of HCN2 channels provides neuroprotection against OGD/R and TGCI by accelerating autophagic degradation attributable to the promotion of autophagosome and lysosome fusion.

Effect of kang naoxueshuan tablet on protecting ischemic brain injury in rats / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the protective effect of Kang Naoxueshuan Tablet (KNT) on ischemic brain injury in rats, and explore its possible mechanism.</p><p><b>METHODS</b>Rats were administrated with KNT twice per day for successive 14 days. Rat model of acute focal cerebral ischemia was established by middle cerebral artery occlusion (MCAO) with a nylon suture inserted through the right internal carotid artery to occlude the beginning of middle cerebral artery. After 24 hrs MCAO, the neurological deficit and the volume of cerebral infarct were observed, and the effect of KNT on the thrombosis of rats in vitro, platelet aggregation and blood viscosity were also determined.</p><p><b>RESULTS</b>KNT could alleviate volume of cerebral infarct caused by focal cerebral ischemia in a dose-dependent manner and improve neurological symptoms. The volume of cerebral infarct was 11. 18 +/- 3. 35% , 14. 60 +/- 7.00% and 15. 37 +/- 7. 21% in the high, middle and low-dose groups, respectively, and they were decreased 59. 36% , 46. 93% and 44. 13% than that in the model group 27. 51 +/- 4. 71% (P <0. 01 ). The wet and dry weigh of thrombosis in vitro of the three different dose groups were significantly decreased, and they were significantly different than that of the model group (P <0. 05, P <0. 01). KNT could significantly inhibit platelet aggregation induced by ADP and decrease blood viscosity, but it had no effect on plasma viscosity and hematocrit.</p><p><b>CONCLUSION</b>KNT has significant protective effect on ischemia, the mechanism is relateed to the improvement of blood viscosity and inhibiti on of platelet aggregation. But the exact mechanisms need to be probed into deeply.</p>

ZD7288 inhibits the synaptic transmission in the pathway from perforant pathway fibers to CA3 region in rat hippocampus / 药学学报

<p><b>AIM</b>To study the effect of ZD7288 on synaptic transmission in the pathway from perforant pathway (PP) fibers to CA3 region in rat hippocampus.</p><p><b>METHODS</b>The extracellular recording technique in vivo was used to record the CA3 region field potentials. High-performance liquid chromatography (HPLC) with fluorescence detection was applied to measure the content of amino acids in hippocampal tissues. The effect of ZD7288 and CsCl on the amplitudes of population spike (PS) in CA3 region evoked by stimulation (0.5 Hz) of the perforant pathway (PP) fibers, and the content of amino acids in hippocampal tissue were observed.</p><p><b>RESULTS</b>Microinjection of ZD7288 (20, 100 and 200 nmol) and CsCl (1, 5 and 10 micromol) into CA3 region decreased the population spike (PS) amplitudes in a dose-dependent manner. The inhibitory effects appeared at 5 min after microinjection and lasted at least 90 min. In those rats treated with ZD7288 (100 nmol), the contents of glutamate, aspartate, glycine and GABA decreased significantly as compared to those of saline control (all P < 0.01, except P < 0.05 for that of glycine). A similar decrease in the contents of amino acids was observed when the rats were microinjected with CsCl (5 micromol). CONCLUSION; ZD7288 could obviously inhibit synaptic transmission in the pathway from PP fibers to CA3 region in rat hippocampus, and this action of ZD7288 may be associated with altered contents of amino acids.</p>

Protective effect of nitric oxide on gastric mucosa and its relationship to the acid secretion of gastric parietal cells under stress in rats / 中国应用生理学杂志

<p><b>AIM</b>To demonstrate the protective effect of nitric oxide (NO) on gastric mucosa and its relationship to the acid secretion of parietal cells under stress in rats.</p><p><b>METHODS</b>Water immersion-restraint stress (WRS) model in SD rats was performed. The gastric mucosal ulcer index (UI), NO contents in gastric mucosa and H+, K(+) -ATPase activity of parietal cells were measured. The effects of N(G)-nitro-L-arginine methyl ester(L-NAME) and L-arginine (L-Arg) on the H+, K(+)-ATPase activity of parietal cells and stress-induced gastric mucosal lesion were observed.</p><p><b>RESULTS</b>L-NAME pretreatment decreased NO contents in gastric mucosa, activated H+, K(+) -ATPase activity of parietal cells and aggravated gastric mucosal lesion, whereas L-Arg pretreatment increased NO contents, inhibited H+, K(+) -ATPase activity and significantly ameliorated stress-induced gastric mucosal lesion.</p><p><b>CONCLUSION</b>Endogenous nitric oxide plays an important role in protecting gastric mucosa from stress-induced lesion by inhibiting H+, K(+) -ATPase activity of parietal cells.</p>

Protective effects of phenolic alkaloids from Menispermum dauricum on inflammatory injury following focal cerebral ischemia-reperfusion in rats / 药学学报

<p><b>AIM</b>To study the protective effects of phenolic alkaloids from Menispermum dauricum (PAMd) on inflammatory injury following focal cerebral ischemia-reperfusion in rats.</p><p><b>METHODS</b>The right middle cerebral artery of the rat was occluded by inserting a nylon suture through the internal carotid artery for 2 h, followed by reperfusion by withdrawing the suture. The expression of intercellular adhesion molecule-1 (ICAM-1) was observed by immunohistochemistry staining. The adhesiveness and infiltration of leucocytes were observed by HE staining. The activity of myeloperoxidase (MPO) and the content of nitric oxide (NO) in the cortex and hippocampus were measured.</p><p><b>RESULTS</b>PAMd was shown to markedly inhibit ICAM-1 expression, alleviate the adhesiveness and infiltration of leucocytes, and decrease the MPO activity and the NO content in ischemic cortex and hippocampus.</p><p><b>CONCLUSION</b>PAMd has protective effects on inflammatory injury following focal cerebral ischemia-reperfusion by inhibiting ICAM-1 expression, alleviating the adhesiveness and infiltration of leucocytes and decreasing the generation of NO.</p>

Protective effects of 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride(DDPH) on brain ischemia injury in rats / 药学学报

<p><b>AIM</b>To study the effects of 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride(DDPH) on brain ischemia injury in rats.</p><p><b>METHODS</b>By using the middle cerebral artery occlusion (MCAO) induced by nylon surgical thread inserted through the internal carotid artery into the anterior cerebral artery in rats, the effects of DDPH on neuron defects(ND) and infarct size(IS) were investigated. Using incomplete cerebral ischemia in rats, the effects of DDPH on superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in brain tissue and pathological changes in rats were studied.</p><p><b>RESULTS</b>DDPH at the dose of 10 mg.kg-1 i.p. 30 min before ischemia decreased the ND 3 h after ischemia. The IS declined 24 h after ischemia as well. Meanwhile, DDPH was found to increase SOD activity and reduce the MDA content, as well as mitigate pathological damage, of neuron after brain ischemia in rats.</p><p><b>CONCLUSION</b>DDPH showed protective effects on brain ischemia, probably related to its properties of calcium antagonistic effect and increasing the activity of superoxide dismutases.</p>