生理学知识点多,理解难度大,一直是基础医学教学的难点.翻转课堂作为一种新兴教学模式被广泛地应用到医学教育领域.文章以"窦弓反射"为例,进一步探究了基于微课的翻转课堂教学模式在生理学教学中的应用.

Background: Hypertension is characterized by sympathetic overactivity, which is associated with an enhancement in angiotensin receptor type I (AT1R) in the rostral ventrolateral medulla (RVLM). β-arrestin1, a canonical scaffold protein, has been suggested to show a negative effect on G protein-coupled receptors via its internalization and desensitization and/or the biased signaling pathway. The major objectives of the present study were to observe the effect of β-arrestin1 overexpression in the RVLM on cardiovascular regulation in spontaneously hypertensive rats (SHR), and further determine the effect of β-arrestin1 on AT1R expression in the RVLM. Methods: The animal model of β-arrestin1 overexpression was induced by bilateral injection of adeno-associated virus containing Arrb1 gene (AAV-Arrb1) into the RVLM of WKY and SHR. Results: β-arrestin1 was expressed on the pre-sympathetic neurons in the RVLM, and its expression in the RVLM was significantly (P < 0.05) downregulated by an average of 64% in SHR than WKY. Overexpression of β-arrestin1 in SHR significantly decreased baseline levels of blood pressure and renal sympathetic nerve activity, and attenuated cardiovascular effects induced by RVLM injection of angiotensin II (100 pmol). Furthermore, β-arrestin1 overexpression in the RVLM significantly reduced the expression of AT1R by 65% and NF-κB p65 phosphorylation by 66% in SHR. It was confirmed that β-arrestin1 overexpression in the RVLM led to an enhancement of interaction between β-arrestin1 and IκB-α. Conclusion: Overexpression of β-arrestin1 in the RVLM reduces BP and sympathetic outflow in hypertension, which may be associated with NFκB-mediated AT1R downregulation.

翻转课堂这一概念的提出已将近30年,特别是近些年来随着新媒体在教学实践中的广泛应用,使得翻转课堂这一教学模式被越来越多的师生所认可.相比于传统教学模式,翻转课堂更加注重学生自主学习能力的培养,改变了师生在传统教学过程中的定位.课堂教学在培养学生创新能力上存在一定的局限性,第二课堂活动对于培养学生创新能力具有课堂教学无法比拟的优越性.本文拟对医学本科生第二课堂教学中存在的问题进行分析,阐述医学本科生第二课堂教学中进行翻转课堂的优势以及设计思路,探析翻转课堂在医学本科生第二课堂教学中的作用,为医学本科生第二课堂教学模式创新提供参考和借鉴.

Neuropathic pain increases the risk of cardiovascular diseases including hypertension with the characteristic of sympathetic overactivity. The enhanced tonically active glutamatergic input to the rostral ventrolateral medulla (RVLM) contributes to sympathetic overactivity and blood pressure (BP) in cardiovascular diseases. We hypothesize that neuropathic pain enhances tonically active glutamatergic inputs to the RVLM, which contributes to high level of BP and sympathetic outflow. Animal model with the trigeminal neuropathic pain was induced by the infraorbital nerve-chronic constriction injury (ION-CCI). A significant increase in BP and renal sympathetic nerve activity (RSNA) was found in rats with ION-CCI (BP, n = 5, RSNA, n = 7, p < 0.05). The concentration of glutamate in the RVLM was significantly increased in the ION-CCI group (n = 4, p < 0.05). Blockade of glutamate receptors by injection of kynurenic acid into the RVLM significantly decreased BP and RSNA in the ION-CCI group (n = 5, p < 0.05). In two major sources (the paraventricular nucleus and periaqueductal gray) for glutamatergic inputs to the RVLM, the ION-CCI group (n = 5, p < 0.05) showed an increase in glutamate content and expression of glutaminase 2, vesicular glutamate transporter 2 proteins, and c-fos. Our results suggest that enhancement in tonically active glutamatergic inputs to the RVLM contributes to neuropathic pain-induced high blood pressure.

The imbalance between angiotensin II (Ang II) and angiotensin 1–7 (Ang 1–7) in the brain has been reported to contribute to cardiovascular dysfunction in hypertension. Exercise training (ExT) is beneficial to hypertension and the mechanism is unclear. This study was aimed to determine if ExT improves hypertension via adjusting renin angiotensin system in cardiovascular centers including the rostral ventrolateral medulla (RVLM). Spontaneously hypertensive rats (SHR, 8 weeks old) were subjected to low-intensity ExT or kept sedentary (Sed) for 12 weeks. Blood pressure elevation coupled with increase in age was significantly decreased in SHR received ExT compared with Sed. The results in vivo showed that ExT significantly reduced or increased the cardiovascular responses to central application of sarthran (antagonist of Ang II) or A779 (antagonist of Ang 1–7), respectively. The protein expression of the Ang II acting receptor AT1R and the Ang 1–7 acting receptor Mas in the RVLM was significantly reduced and elevated in SHR following ExT, respectively. Moreover, production of reactive oxygen species in the RVLM was significantly decreased in SHR following ExT. The current data suggest that ExT improves hypertension via improving the balance of Ang II and Ang 1–7 and antioxidative stress at the level of RVLM.

Objective:Centrally acting antihypertensive action of moxonidine is a result of activation of Imidazoline-1 receptor (I1R) in the rostral ventrolateral medulla (RVLM). Hypertension shows an increase in reactive oxygen species (ROS) in the RVLM. The present objective was to determine the phosphoinositide-3 kinase (PI3K) signaling pathway involved in the effect of moxonidine on ROS generation in the RVLM of spontaneously hypertensive rat (SHR).Methods:Wistar-Kyoto rats and SHR received intracisternal infusion (2 weeks) of tested agents which were subjected to subsequent experiments. In-situ ROS in the RVLM was evaluated by the oxidative fluorescence dye. Western blot and PCR analysis were performed to detect the expression levels of PI3K signaling pathway. Lentivirus was injected bilaterally into the RVLM for silencing PI3K signaling.Results:ROS production in the RVLM was dose-dependently reduced in SHRs treated with infusion of moxonidine (20nmol/day), which was prevented by the I1R antagonist efaroxan but not by the (2)-adrenoceptor antagonist yohimbine. Moxonidine pretreatment significantly blunted cardiovascular sensitivity to injection of tempol (5 nmol) or angiotensin II (10 pmol) into the RVLM in SHR. Expression levels of PI3K/Akt, nuclear factor kappa-B (NFB), NADPHase (NOX4), and angiotensin type I receptor (AT(1)R) in the RVLM were markedly decreased in SHR treated with moxonidine. Infection of lentivirus containing PI3K shRNA in the RVLM effectively prevented effects of moxonidine on cardiovascular activity and expression levels of Akt, NFB, NOX4, and AT(1)R.Conclusion:The centrally antihypertensive drug moxonidine decreases ROS production in the RVLM through inactivation of the PI3K/Akt signaling pathway in hypertension.

Angiotensin-1-7 [Ang-(1-7)], acting via the Mas receptor in the central nervous system, is involved in the regulation of cardiovascular activity. Nitric oxide (NO) is implicated as an important modulator in the nucleus tractus solitarii (NTS), a key region involved in control of cardiovascular activity. The aim of the present study was to determine the role of phosphatidylinositol 3-kinase (PI3K) signaling in mediating the effect of Ang-(1-7) on NO generation in the NTS. In Sprague-Dawley rats, acute injection of Ang-(1-7) into the NTS significantly increased NO generation and neuronal/endothelial NO synthase (n/eNOS) activity, which were abolished by the selective Mas receptor antagonist D-Alanine-[Ang-(1-7)] (A-779), the PI3K inhibitor LY294002, or the Akt inhibitor triciribine (TCN). Western blotting analysis further demonstrated that Ang-(1-7) significantly increased levels of Akt/NOS phosphorylation in the NTS, and Ang-(1-7)-induced e/nNOS phosphorylation was antagonized by LY294002 or TCN. Furthermore, gene knockdown of PI3K by lentivirus containing small hairpin RNA in the NTS prevented the Ang-(1-7)-induced increases in NOS/Akt phosphorylation and NO production. The physiological (in vivo) experiments showed that pretreatment with the NOS inhibitor L-NAME, LY294002, or TCN abolished the decreases in blood pressure, heart rate, and renal sympathetic nerve activity induced by Ang-(1-7) injected into the NTS. Our findings suggest that nitric oxide release meditated by the Mas-PI3K-NOS signaling pathway is involved in the cardiovascular effects of Ang-(1-7) in the NTS. (C) 2015 Elsevier Inc. All rights reserved.

AIMS:It is well known that low-intensity exercise training (ExT) is beneficial to cardiovascular dysfunction in hypertension. The tonically active glutamatergic input to the rostral ventrolateral medulla (RVLM), a key region for control of blood pressure and sympathetic tone, has been demonstrated to be increased in hypertensive rats. The aim of this study was to determine the effect of ExT on the increased glutamatergic input to the RVLM in spontaneously hypertensive rat (SHR).METHODS:Normotensive rats Wistar-Kyoto (WKY) and SHR were treadmill trained or remained sedentary (Sed) for 12 weeks and classed into four groups (WKY-Sed, WKY-ExT, SHR-Sed, and SHR-ExT). The release of glutamate in the RVLM and its contribution to cardiovascular activity were determined in WKY and SHR after treatment of ExT.RESULTS:Blood pressure and sympathetic tone were significantly reduced in SHR after treatment with ExT. Bilateral microinjection of the glutamate receptor antagonist kynurenic acid (2.7 nmol in 100 nL) into the RVLM significantly decreased resting blood pressure, heart rate, and renal sympathetic nerve activity in SHR-Sed but not in WKY groups (WKY-Sed and WKY-ExT). However, the degree of reduction in these cardiovascular parameters evoked by KYN was significantly blunted in SHR-ExT compared with SHR-Sed group. The concentration of glutamate and the protein expression of vesicular glutamate transporter 2 in the RVLM were significantly increased in SHR-Sed compared with WKY-Sed, whereas they were reduced after treatment with ExT.CONCLUSION:Our findings suggest that ExT attenuates the enhancement in the tonically acting glutamatergic input to the RVLM of hypertensive rats, thereby reducing the sympathetic hyperactivity and blood pressure.

The rostral ventrolateral medulla (RVLM) plays a critical role in control of cardiovascular regulation. The increased tonic glutamatergic input to the RVLM contributes to high blood pressure and enhanced sympathetic outflow in hypertensive rats. Recently, it has been reported that overexpression of angiotensin-converting enzyme 2 (ACE2) is capable of lowering high blood pressure in the spontaneously hypertensive rat (SHR). Thus, the aim of this study was to determine the effect of ACE2 gene transfer on tonically acting glutamatergic input to the RVLM in the SHR. It was confirmed that protein expression of ACE2 in the RVLM was increased by an average of 66% in the SHR treated with lentiviral-mediated overexpression of ACE2 (lenti-ACE2) compared with lenti-green fluorescent protein (GFP). A significant reduction in resting blood pressure and the 24-h urinary excretion of norepinephrine was observed in the SHR treated with lenti-ACE2 in the RVLM compared with lenti-GFP. Overexpression of ACE2 significantly reduced the concentration of glutamate (1586±142 μg/L in lenti-GFP versus 621±60 μg/L in lenti-ACE2) from microdialysis-liquid from the RVLM of the SHR. Furthermore, a decrease in resting blood pressure, heart rate, and renal sympathetic nerve activity evoked by microinjection of the glutamate receptor antagonist kynurenic acid (2.7 nmol) into the RVLM was significantly blunted in the SHR treated with lenti-ACE2 compared with lenti-GFP. Based on these data, we suggest that the beneficial effect of ACE2 overexpression in the RVLM on hypertension is associated with reduction in the tonically acting glutamatergic input to the RVLM. (Supported by NSCF: 81170240)

Objective To observe the effect of nitric oxide(NO)on cardiovascular activities in the nucleus tractus solitarii(NTS) and the rostral ventrolateral medulla(RVLM),so as to understand the role of central NO in cardiovascular regulation.Methods The changes of blood pressure(BP),heart rate(HR),and renal sympathetic nerve activity(RSNA) were observed following treatments with increased or decreased NO in the NTS and RVLM of anaesthetized SD rats.Results Microinjection of the NO precusor L-arginine(L-Arg,2 nmol in 50 nl) into the NTS,a key relay of cardiovascular reflex transmission,produced significant decreases in BP,HR,and RSNA(P0.05),and injection of NO synthase inhibitor NG-nitro-L-arginine methyl ester(L-NAME,10 nmol in 50 nl) into the NTS produced significant increases in these cardiovascular parameters(P0.05).However,injection of L-Arg(2 nmol in 100 nl) into the RVLM,a key region controlling sympathetic outflow,significantly increased basal BP,HR,and RSNA(P0.05),and injection of L-NAME(10 nmol in 100 nl) into the RVLM showed a cardiovascular inhibition effect(P0.05).Conclusion NO exhibits different effects in different cardiovascular centers,suggesting that it plays a special role in maintaining the basal cardiovascular activity.