[Involvement of cross interaction between central cholinergic and histaminergic systems in the nucleus tractus solitarius in regulating carotid sinus baroreceptor reflex].

The carotid sinus baroreceptor reflex (CSR) is an important approach for regulating arterial blood pressure homeostasis instantaneously and physiologically. Activation of the central histaminergic or cholinergic systems results in CSR functional inhibitory resetting. However, it is unclear whether two systems at the nucleus tractus solitarius (NTS) level display cross interaction to regulate the CSR or not. In the present study, the left or right carotid sinus region was isolated from the systemic circulation in Sprague-Dawley rats (sinus nerve was reserved) anesthetized with pentobarbital sodium. Respective intubation was conducted into one side isolated carotid sinus and into the femoral artery for recording the intracarotid sinus pressure (ISP) and mean arterial pressure (MAP) simultaneously with pressure transducers connection in vivo. ISP was set at the level of 0 mmHg to eliminate the effect of initial internal pressure of the carotid sinus on the CSR function. To trigger CSR, the ISP was quickly elevated from 0 mmHg to 280 mmHg in a stepwise manner (40 mmHg) which was added at every step for over 4 s, and then ISP returned to 0 mmHg in similar steps. The original data of ISP and corresponding MAP were fitted to a modified logistic equation with five parameters to obtain the ISP-MAP, ISP-Gain relationship curves and the CSR characteristic parameters, which were statistically compared and analyzed separately. Under the precondition of no influence on the basic levels of the artery blood pressure, the effects and potential regulatory mechanism of preceding microinjection with different cholinoceptor antagonists, the selective cholinergic M1 receptor antagonist, i.e., pirenzepine (PRZ), the M2 receptor antagonist, i.e., methoctramine (MTR) or the N1 receptor antagonist, i.e., hexamethonium (HEX) into the NTS on the changes in function of CSR induced by intracerebroventricular injection (i.c.v.) of histamine (HA) in rats were observed. Meanwhile, the actions and possible modulatory mechanism of preceding microinjection with different histaminergic receptor antagonists, the selective histaminergic H1 receptor antagonist, i.e., chlorpheniramine (CHL) or the H2 receptor antagonist, i.e., cimetidine (CIM) into the NTS on the changes in function of CSR resulted from the i.c.v. cholinesterase inhibitor, physostigmine (PHY) were also examined in order to confirm and to analyze effects of cross interaction between central histaminergic and cholinergic systems on CSR. The main results obtained are as follows. (1) Standalone microinjection of different selective cholinergic receptor antagonists (PRZ, MTR or HEX) or different selective histaminergic receptor antagonists (CHL or CIM) into the NTS with each given dose had no effects on the CSR function and on the basic levels of the artery blood pressure, respectively (P > 0.05). (2) The pretreatment of PRZ or MTR into the NTS with each corresponding dose could attenuate CSR resetting resulted from i.c.v. HA in some degrees, which remarkably moved the posterior half range of ISP-MAP relationship curve downwards (P < 0.05), shifted the middle part of ISP-Gain relationship curve upwards (P < 0.05), and increased reflex parameters such as the MAP range and maximum gain (P < 0.05), but decreased parameters such as saturation pressure and intracarotid sinus pressure at maximum gain (P < 0.05). The catabatic effects of pretreatment with MTR into the NTS on CSR resetting induced by i.c.v. HA were more obvious than those with PRZ (P < 0.05), but pretreatment of HEX with given dose into the NTS had no effects on CSR resetting induced by i.c.v. HA (P > 0.05). (3) The effects of pretreatment of CHL or CIM into the NTS with each corresponding dose on CSR resetting made by i.c.v. PHY were similar to those of pretreatment of PRZ or MTR into the NTS on CSR resetting resulted from i.c.v. HA, and the decreasing effects of pretreatment with CHL into the NTS on CSR resetting induced by i.c.v. PHY were more remarkable than those with CIM (P < 0.05). These findings suggest that CSR resetting resulted from either HA or PHY into the lateral ventricle may partly involve the descending histaminergic or cholinergic pathway from the hypothalamus to NTS, which might evoke a cross activation of the cholinergic system in the NTS, via cholinergic M1 and M2 receptors mediation, especially the M2 receptors showing actions, or trigger another cross activation of the histaminergic system in the NTS, by histaminergic H1 and H2 receptors mediation, especially the H1 receptors displaying effects.

Knockdown of lncRNA SNHG1 alleviates oxygen-glucose deprivation/reperfusion-induced cell death by serving as a ceRNA for miR-424 in SH-SY5Y cells.

Objective: Long non-coding RNAs (lncRNAs) are theorized to serve a critical role in cerebral ischemia/reperfusion injury. The purpose of this study was to determine whether knockdown of lncRNA SNHG1 protected against oxygen-glucose deprivation/reperfusion (OGD/R)-induced cell death in vitro and to investigate the underlying mechanisms. Methods: The expression levels of SNHG1 and miR-424 were detected by RT-qPCR analysis. The expression levels of apoptosis-related proteins were detected by western blot analysis. Cell viability and apoptosis were detected by MTT assay and flow cytometric analysis, respectively. Bioinformatic prediction and dual-luciferase reporter assay were performed to study the interaction between SNHG1 and miR-424. Results: The results showed that SNHG1 expression level was increased in OGD/R-treated SH-SY5Y cells, and knockdown of SNHG1 alleviates OGD/R-induced apoptosis and mitochondrial dysfunction in SH-SY5Y cells. Moreover, we found that SNHG1 might serve as a ceRNA for miR-424 in SH-SY5Y cells, and rescue experiments further confirmed that miR-424 inhibitor blocked the beneficial role of SNHG1 knockdown in OGD/R-treated SH-SY5Y cells. Conclusion: Taken together, this research supported the first evidence that lncRNA SNHG1 regulates OGD/R-induced cell death through serving as a ceRNA for miR-424 in SH-SY5Y cells.

Neuroprotective role of fucoxanthin against cerebral ischemic/reperfusion injury through activation of Nrf2/HO-1 signaling.

In the present study, an attempt was made to determine whether administration of fucoxanthin could attenuate cerebral ischemic/reperfusion (I/R) injury and its possible mechanisms using an in vivo middle cerebral artery occlusion (MCAO) model and an in vitro oxygen-glucose deprivation and reoxygenation (OGD/R) model. Fucoxanthin was intragastrically administrated in different doses (30 mg/kg, 60 mg/kg, and 90 mg/kg, respectively) to the rats 1 h before MCAO induction. The neurological function, infarct area and brain water content of rats were then evaluated. Rat cortical neuron were pretreated with different doses of fucoxanthin (5 µM, 10 µM, and 20 µM) and then subjected to OGD/R. Expression levels of proteins in the brain tissues and cultured cells were determined by western blotting. Our results demonstrated that fucoxanthin pretreatment improved the neurologic deficit score, lowered the infarct volume and reduced the expression of apoptosis-associated proteins in brain tissues. In addition, fucoxanthin also suppresses OGD/R-induced apoptosis and ROS accumulation in cultured neurons. Furthermore, we found that fucoxanthin could significantly activate the Nrf2/HO-1 signaling through inducing Nrf2 nuclear translocation with enhanced HO-1 expression, and Nrf2 knockdown obviously abrogated the beneficial role of fucoxanthin in OGD/R-treated neurons. These findings suggested that fucoxanthin could be exploited as a therapeutic target for protecting neurons from cerebral I/R injury.

MicroRNA-93 inhibits inflammatory responses and cell apoptosis after cerebral ischemia reperfusion by targeting interleukin-1 receptor-associated kinase 4.

The present study aimed to investigate changes in the expression of interleukin (IL)-1 receptor-associated kinase 4 (IRAK4) and microRNA (miRNA or miR)-93 in mice with cerebral ischemia reperfusion (CIR) injury, as well as the association and regulatory mechanism between IRAK4 and miR-93. The CIR mouse model was constructed and mouse microglia BV2 cells were transfected with miR-93 mimic or miR-93 inhibitor. Quantitative polymerase chain reaction was used to measure the expression of mRNA and miR-93. Western blotting was performed to determine protein expression. Enzyme-linked immunosorbent assays were performed to measure the concentrations pro-inflammatory factors. The expression of miR-93 in CIR mice brains was significantly reduced, while Ago-miR-93 (a type of miRNA analog) increased its expression. Ago-miR-93 alleviated neurological deficits and reduced cerebral infarction volume in the mice. Furthermore, Ago-miR-93 inhibited inflammatory responses following CIR. Ago-miR-93 decreased the rate of cell apoptosis following CIR. In addition, miR-93 downregulated IRAK4 protein expression, but did not alter its mRNA expression levels in BV2 cells. miR-93 expression reduced the expression of pro-inflammatory factors in BV2 cells. Ago-miR-93 inhibited IRAK4 expression in the brain tissues of CIR mice. The present study demonstrated that miR-93 inhibits inflammatory responses and cell apoptosis following CIR by targeting the IRAK4 signaling pathway.

Apoptosis and autophagy contribute to gender difference in cardiac ischemia-reperfusion induced injury in rats.

AIMS: Gender difference in cardiac ischemia-reperfusion (IR) induced injury has been reported in animal models. However, a large-scale clinical trial found an increase in cardiovascular incidents in women with hormone replacement therapy. The present study is aimed to explore possible mechanisms of gender difference in cardiac IR induced injury. MAIN METHODS: Male and female Sprague-Dawley rats were subjected to a 30-min coronary arterial occlusion followed by reperfusion. The infarct size and apoptotic cell number at 24h after reperfusion were significantly lower in female rats than in male rats. KEY FINDINGS: Male rats expressed higher anti-apoptotic protein Bcl2 levels compared with female rats under physiological conditions. However, levels of Bcl2 were reduced significantly after IR in male rats but not in, female rats. Levels of pro-apoptotic protein, Bax and phospho-p38, showed similar under physiological conditions. In response to IR expression of Bax was markedly reduced in female rats but not in male rats, and expression of phospho-p38 was significantly increased in male rats but not in female rats. In addition, female rats showed marked increase of autophagy marker, ratio of LC3B to LC3A, while male rats significantly decreased the ratio in response to IR. SIGNIFICANCE: Gender difference in IR injury is due to the different regulation of anti-apoptotic protein, pro-apoptotic protein and autophagy protein levels in male rats and levels in female rats. Our results provide better understanding of sex differences in cardiac IR injury.