Glucocorticoids and endocannabinoids in vagal complex

在这项研究拨款提案的实验将确定细胞和突触的影响， 内源性大麻素（eCB）配体和糖皮质激素诱导的eCB在背侧运动中的释放 迷走神经核（DMV）DMV中的神经元调节副交感神经输出到大多数神经元。 下丘脑内脏，因此严格控制进食、消化、葡萄糖和胰岛素分泌， 和其他代谢功能。它们的活动在很大程度上受DMV的突触输入控制， 由局部释放的化学物质和循环激素调节。DMV神经元的调节 大麻素、香草素和糖皮质激素已经被建议;当集中应用时，这些 化合物深刻地改变副交感神经功能。几种eCB配体，被认为是 以逆行方式从细胞膜释放，激活大麻素1型受体（CB 1 R） 和瞬时受体电位香草酸1型（TRPV 1）。在DMV中，TRPV 1的激活增强了 CB 1 R倾向于抑制神经递质释放，而CB 1 R倾向于抑制突触。这两种效应都是通过激活 突触前末梢上的受体。初步证据表明，eCB配体是从 糖皮质激素或去极化可以诱导这种释放。因此，eCB活性在 DMV可以调节TRPV 1和CB 1 R活性。释放的eCB配体的类型， 大多数eCB配体对突触活动的影响，也不是DMV中eCB释放的触发或机制 是已知的。我们将使用脑干切片中DMV神经元的全细胞膜片钳记录， 确定eCB配体对DMV中细胞活性的影响，还将确定释放的化合物 通过药理学和生物化学的方法。这些实验将由 三个具体目标：1）区分eCB配体对DMV中CB 1 R和TRPV 1的影响; 2）确定 eCB参与介导糖皮质激素对DMV局部电路的快速作用;以及3） 确定糖皮质激素作用的细胞途径。我们将检验eCB改变 TRPV 1和CBR 1在DMV中的活性在特定的和可预测的空间，时间，功能相关， 和活性依赖模式，糖皮质激素通过作用于DMV细胞诱导eCB释放， DMV神经元上的膜结合G蛋白偶联受体。基于eCB系统的药物是 正在研究其在各种神经系统病理学中的治疗用途，包括疾病 与进食、消化和肥胖有关。糖皮质激素在某些系统中释放eCB， 被广泛地规定，并且也被压力刺激释放。这些研究的结果将是至关重要的 预测和了解这些化合物如何相互作用，并影响副交感神经 功能可能的转化效益也存在，因为控制eCB水平的好处， 糖皮质激素升高患者的迷走神经系统。

The experiments in this research grant proposal will identify the cellular and synaptic effects of endogenous cannabinoid (eCB) ligands and of glucocorticoid-induced release of eCBs in the dorsal motor nucleus of the vagus (DMV). Neurons in the DMV regulate parasympathetic output to most of the subdiaphragmatic viscera and therefore critically control feeding, digestion, glucose and insulin secretion, and other metabolic functions. Their activity is largely controlled by synaptic input to the DMV, which is modulated by locally released chemicals and circulating hormones. Regulation of DMV neurons by cannabinoids, vanilloids, and glucocorticoids has been suggested; when applied centrally these compounds profoundly alter parasympathetic function. Several eCB ligands, which are thought to be released from cell membranes in a retrograde fashion, activate both cannabinoid type 1 receptors (CB1R) and transient receptor potential vanilloid type 1 (TRPV1). In the DMV, activation of TRPV1 enhances neurotransmitter release, whereas CB1R tends to inhibit synapses. Both effects occur by activation of receptors on presynaptic terminals. Preliminary evidence suggests that eCB ligands are released from DMV neurons, and that glucocorticoids or depolarization can induce this release. Thus, eCB activity in the DMV may modulate both TRPV1 and CB1R activity. Neither the type(s) of eCB ligands released, the effects of most eCB ligands on synaptic activity, nor the trigger or mechanism of eCB release in the DMV are known. We will use whole-cell patch-clamp recordings from DMV neurons in brainstem slices to identify effects of eCB ligands on cellular activity in the DMV, and will also identify the compounds released by cells in the area using pharmacological and biochemical methods. The experiments will be guided by three specific aims: 1) Differentiate effects of eCB ligands on CB1R and TRPV1 in the DMV; 2) Determine the eCB involvement in mediating rapid effects of glucocorticoids on local circuitry in the DMV; and 3) Identify the cellular pathway of the glucocorticoid effect. We will test the hypotheses that eCBs alter TRPV1 and CBR1 activity in the DMV in specific and predictable spatial, temporal, functionally relevant, and activity-dependent patterns, and that glucocorticoids induce eCB release from DMV cells by acting at membrane-bound G protein-coupled receptors on DMV neurons. Drugs based on the eCB system are being investigated for therapeutic use in a variety of nervous system pathologies, including disorders related to feeding, digestion, and obesity. Glucocorticoids, which release eCBs in some systems, are widely prescribed, and are also released by stressful stimuli. Results of these studies will be critical to predicting and understanding how these compounds interact with each other and affect parasympathetic function. Possible translational benefits also exist because of the benefit in controlling eCB levels in the vagal system of patients with elevated glucocorticoids.