Tao Ban

MicroRNA-195 Protects Against Dementia Induced by Chronic Brain Hypoperfusion via Its Anti-Amyloidogenic Effect in Rats

Previous studies have demonstrated that chronic brain hypoperfusion (CBH) causes Aβ aggregation by upregulating expression of amyloid precursor protein (APP) and β-site APP cleaving enzyme 1 (BACE1) protein, which is accompanied by cognitive impairment, but the mechanisms are not fully understood. In this study, we evaluated the effect of microRNA on memory impairment in rats induced by CBH. We show here that CBH generated by bilateral common carotid artery occlusion (2VO) significantly decreased the learning and memory ability in rats, as assessed by Morris water maze, and upregulated expression of APP and BACE1 proteins in the hippocampus and cortex of rats, as evaluated by Western blot and immunofluorescence. In reciprocal, qRT-PCR analysis showed that microRNA-195 (miR-195) was downregulated in both the hippocampus and cortex of rats following CBH, and in the plasma of dementia patients. APP and BACE1 proteins were downregulated by miR-195 overexpression, upregulated by miR-195 inhibition, and unchanged by binding-site mutation or miR-masks, indicating that APP and BACE1 are two potential targets for miR-195. Knockdown of endogenous miR-195 by lentiviral vector-mediated overexpression of its antisense molecule (lenti-pre-AMO-miR-195) elicited dementia in rats, whereas overexpression of miR-195 using lenti-pre-miR-195 reduced dementia vulnerability triggered by 2VO. Additionally, chromatin immunoprecipitation analysis showed that NFκB was bound to the promoter region of miR-195 and inhibited its expression. We conclude that miR-195 may play a key role in determining dementia susceptibility in 2VO rats by regulating APP and BACE1 expression at the post-transcriptional level, and exogenous complement of miR-195 may be a potentially valuable anti-dementia approach.

Activation of Cdk5/p25 and tau phosphorylation following chronic brain hypoperfusion in rats involves microRNA-195 down-regulation.

Chronic brain hypoperfusion (CBH) is a common clinical feature of Alzheimers disease and vascular dementia, but the underlying molecular mechanism is unclear. Our previous study reported that the down‐regulation of microRNA‐195 (miR‐195) promotes amyloidogenesis via regulation of amyloid precursor protein and β‐site amyloid precursor protein cleaving enzyme 1 (BACE1) expression at the post‐transcriptional level in CBH rats with bilateral common carotid artery occlusion (2VO). CBH owing to unilateral common carotid artery occlusion (UCCAO) increases tau phosphorylation levels at multiple phosphorylation sites in the brain, but the molecular mechanism is poorly understood. The purpose of this study was to investigate whether miR‐195 could both deregulate amyloid metabolism and indirectly deregulate tau phosphorylation in CBH. We observed that 2VO leads to tau hyperphosphorylation at Ser202/Thr205, Ser262, Thr231, and Ser422 and to the conversion from cyclin‐dependent kinase 5 (Cdk5)/p35 to Cdk5/p25 in rat hippocampi. Endogenous miR‐195 was knocked down using over‐expression of its antisense molecule (pre‐AMO‐miR‐195) via a lentivirus (lenti‐pre‐AMO‐miR‐195); this knockdown increased the tau phosphorylation at Ser202/Thr205, Ser262, Thr231, Ser422, and the Cdk5/p25 activation, but over‐expression of miR‐195 using lenti‐pre‐miR‐195 decreased the tau phosphorylation and Cdk5/p25 activation. Further in vitro studies demonstrated that miR‐195 over‐expression prevented tau hyperphosphorylation and Cdk5/p35 activity, which were increased by miR‐195 inhibition. A dual luciferase reporter assay showed that miR‐195 bound to the Cdk5r1 gene, which encodes p35 protein, in the 3′UTR and inhibited p35 expression. We concluded that tau hyperphosphorylation involves the down‐regulation of miR‐195, which is mediated by Cdk5/p25 activation in 2VO rats. Our findings demonstrated that down‐regulation of miR‐195 led to increased vulnerability via the regulation of multiple targets.

Elevated plasma microRNA-1 predicts heart failure after acute myocardial infarction

Rong Zhang , Huifang Niu , Tao Ban , Ling Xu , Yue Li , Ning Wang , Lihua Sun , Jing Ai ⁎, Baofeng Yang a,⁎ a Department of Pharmacology (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin 150081, China b Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China

Electrophysiological remodeling of linopirdine on neuroexcitability of myelinated A-type baroreceptor neurons in rats

A-type baroreceptor neurons in rats Tao Ban , Jin-Ling Yu , Yu-Yao Zhang , Pan-Xiang Cao , Sheng-Zhi Liu , Xiao-Long Wang , Li-Na Ba , Tian-Ci Zhang , Xin-Jing Guo , Xue Yu , Guo-Fen Qiao ⁎, Bai-Yan Li a,⁎ a Department of Pharmacology, Harbin Medical University, Harbin, China b Key Laboratory of Cardiovascular Research of Ministry of Education, Harbin Medical University, Harbin, China c Department of Anatomy, Histology, and Embryology, Heilongjiang University of Chinese Medicine, Harbin, China

FGF21 ameliorates the neurocontrol of blood pressure in the high fructose-drinking rats.

Fibroblast growth factor-21 (FGF21) is closely related to various metabolic and cardiovascular disorders. However, the direct targets and mechanisms linking FGF21 to blood pressure control and hypertension are still elusive. Here we demonstrated a novel regulatory function of FGF21 in the baroreflex afferent pathway (the nucleus tractus solitarii, NTS; nodose ganglion, NG). As the critical co-receptor of FGF21, β-klotho (klb) significantly expressed on the NTS and NG. Furthermore, we evaluated the beneficial effects of chronic intraperitoneal infusion of recombinant human FGF21 (rhFGF21) on the dysregulated systolic blood pressure, cardiac parameters, baroreflex sensitivity (BRS) and hyperinsulinemia in the high fructose-drinking (HFD) rats. The BRS up-regulation is associated with Akt-eNOS-NO signaling activation in the NTS and NG induced by acute intravenous rhFGF21 administration in HFD and control rats. Moreover, the expressions of FGF21 receptors were aberrantly down-regulated in HFD rats. In addition, the up-regulated peroxisome proliferator-activated receptor-γ and -α (PPAR-γ/-α) in the NTS and NG in HFD rats were markedly reversed by chronic rhFGF21 infusion. Our study extends the work of the FGF21 actions on the neurocontrol of blood pressure regulations through baroreflex afferent pathway in HFD rats.

MicroRNA-9 induces defective trafficking of Nav1.1 and Nav1.2 by targeting Navβ2 protein coding region in rat with chronic brain hypoperfusion

BackgroundPrevious studies have demonstrated that the trafficking defects of Nav1.1/Nav1.2 are involved in the dementia pathophysiology. However, the detailed mechanisms are not fully understood. Moreover, whether the impaired miRNAs regulation linked to dementia is a key player in sodium channel trafficking disturbance remains unclear. The cognitive impairment induced by chronic cerebral ischemia through chronic brain hypoperfusion (CBH) is likely reason to precede dementia. Therefore, our goal in the present study was to examine the role of microRNA-9 (miR-9) in regulating Nav1.1/Nav1.2 trafficking under CBH generated by bilateral common carotid artery occlusion (2VO).ResultsThe impairment of Nav1.1/Nav1.2 trafficking and decreased expression of Navβ2 were found in the hippocampi and cortices of rats following CBH generated by bilateral 2VO. MiR-9 was increased in both the hippocampi and cortices of rats following CBH by qRT-PCR. Intriguingly, miR-9 suppressed, while AMO-miR-9 enhanced, the trafficking of Nav1.1/Nav1.2 from cytoplasm to cell membrane. Further study showed that overexpression of miR-9 inhibited the Navβ2 expression by targeting on its coding sequence (CDS) domain by dual luciferase assay. However, binding-site mutation or miR-masks failed to influence Navβ2 expression as well as Nav1.1/Nav1.2 trafficking process, indicating that Navβ2 is a potential target for miR-9. Lentivirus-mediated miR-9 overexpression also inhibited Navβ2 expression and elicited translocation deficits to cell membrane of Nav1.1/Nav1.2 in rats, whereas injection of lentivirus-mediated miR-9 knockdown could reverse the impaired trafficking of Nav1.1/Nav1.2 triggered by 2VO.ConclusionsWe conclude that miR-9 may play a key role in regulating the process of Nav1.1/Nav1.2 trafficking via targeting on Navβ2 protein in 2VO rats at post-transcriptional level, and inhibition of miR-9 may be a potentially valuable approach to prevent Nav1.1/Nav1.2 trafficking disturbance induced by CBH.

Long-Term Administration of Neuropeptide Y in the Subcutaneous Infusion Results in Cardiac Dysfunction and Hypertrophy in Rats.

Background/Aims: The purpose of the present study was to clarify whether chronically elevated plasma neuropeptide Y (NPY) might affect heart function and cardiac remodeling in rats. Methods: Male Wistar rats were administered NPY (85 μg for 30 days) by mini-osmotic pump subcutaneously implanted between the scapulae. Associated indices for heart function, cardiac remodeling and hypertrophy were evaluated. Results: Compared to the sham group, the baseline systolic blood pressure (SBP) in rats administered NPY was significantly increased; cardiac function was significantly decreased, as indicated by reduced ejection fraction (EF), left ventricular end-systolic pressure (LVESP), maximum change velocity of left ventricular pressure in the isovolumic contraction or relaxation period (±dp/dtmax) and increased left ventricular end-diastolic pressure (LVEDP); hematoxylin-eosin (H&E) staining detection displayed enlarged cell areas and a consistent increase in heart-to-body weight ratios (HW/BW) was observed; quantitative real time PCR (qRT-PCR) and Western blot analysis showed markedly increased expressions of β-myosin heavy chain (β-MHC), calcineurin (CaN) and phosphorylated p38 proteins, while no changes were found in the expressions of p38 total protein and the phosphorylations of JNK and ERK. Conclusion: This study reported for the first time that long-term elevated plasma concentration of NPY could induce cardiac dysfunction and cardiac hypertrophy and this phenomenon could, in part, be mediated by the Ca2+/CaM-dependent CaN pathway and p38 mitogen-activated protein kinase (MAPK) signal pathway in rats.

Neuropeptide Y reverses chronic stress-induced baroreflex hypersensitivity in rats.

Chronic stress, as a risk factor for cardiovascular diseases, has been reported to result in elevated plasma neuropeptide Y (NPY) and be highly associated with abnormal cardiac autonomic function. This study aimed to explore the effect of NPY on the chronic stress-induced abnormal baroreceptor reflex sensitivity (BRS). Seven types of recognized stressors were used to develop chronic stress rat model. Subcutaneously implanting ALZET mini-osmotic pumps containing NPY were used to evaluate the action of NPY on the stressed male rats. We found that chronic stress showed no influence on baseline systolic blood pressure (SBP) and heart rate (HR), whereas NPY (85 µg for 30 days) could elevate baseline SBP and induce bradycardia in rats intervened by various stimuli. NPY pretreatment could preserve chronic stress-induced decreases in left ventricular systolic pressure (LVSP) and the maximum rate of change in left ventricular pressure in the isovolumic contraction period (+dp/dtmax) but has shown no effect on left ventricular end diastolic pressure (LVEDP) and the maximum rate of change in left ventricular pressure in the isovolumic relaxation period (-dp/dtmax). Notably, chronic stress led to baroreflex oversensitivity indicated by the elevated ratio of Δheart rate (HR)/ Δmean arterial blood pressure (MABP) in rats followed by vasoconstrictor (phenylephrine, PE) or vasodilator (sodium nitroprusside, SNP) administration, which was almost completely reversed by NPY pretreatment. The expressions of substance P (SP) and gamma aminobutyric acid A receptor (GABAAR) in nucleus tractus solitarius were increased in chronic stress rats, which were counteracted by NPY pretreatment. We conclude that chronic stress-induced baroreflex hypersensitivity could be blocked by NPY pretreatment. Furthermore, the altered expressions of neurotransmitters and receptors in the brainstem might contribute to this process.

KCa1.1 is potential marker for distinguishing Ah-type baroreceptor neurons in NTS and contributes to sex-specific presynaptic neurotransmission in baroreflex afferent pathway.

Sexual-dimorphic neurocontrol of circulation has been described in baroreflex due largely to the function of myelinated Ah-type baroreceptor neurons (BRNs, 1st-order) in nodose. However, it remains unclear if sex- and afferent-specific neurotransmission could also be observed in the central synapses within nucleus of solitary track (NTS, 2nd-order). According to the principle of no mixed neurotransmission among afferents and differentiation of Ah- and A-types to iberiotoxin (IbTX) observed in nodose, the 2nd-order Ah-type BRNs are highly expected. To test this hypothesis, the excitatory post-synaptic currents (EPSCs) were recorded in identified 2nd-order BRNs before and after IbTX using brain slice and whole-cell patch. These results showed that, in male rats, the dynamics of EPSCs in capsaicin-sensitive C-types were dramatically altered by IbTX, but not in capsaicin-insensitive A-types. Interestingly, near 50% capsaicin-insensitive neurons in females showed similar effects to C-types, suggesting the existence of Ah-types in NTS, which may be the likely reason why the females had lower blood pressure and higher sensitivity to aortic depressor nerve stimulation via KCa1.1-mediated presynaptic glutamate release from Ah-type afferent terminals.

KCa1.1 β4-subunits are not responsible for iberiotoxin-resistance in baroreceptor neurons in adult male rats

channel (BK-KCa, KCa1.1,maxiK) is one of the important ion channel mechanisms in controllingneuroexcitability and neurotransmitter release. In the sensory nervesystem, KCa1.1 plays important roles in mediating afferent reflex, neu-ropathic pain, and other sensory functions. KCa1.1 widely expresses ineither somatic or visceral afferent neuronsincluding baroreceptor neu-rons (BRNs), which are composed of a pore-forming α-subunit andmodulatory β-subunits. Among β-subunits, β4 expressed abundantlyin CNS and plays key roles in Ca