Neurotransmitters in synaptic inputs to medullary neurons subserving the baroreflex

压力感受器能快速调节动脉血压，以满足不断变化的生理需求。这种反射改变血管阻力，改变血液从心脏排出的速度、体积和力量，确保器官获得足够的血液营养和氧气供应。压力感受器反射功能的改变发生在运动过程中，与心力衰竭和心肌梗死的死亡率和发病率增加相关，并与老年人体位性低血压有关。脑干中的三个区域对动脉压力感受性反射的传递至关重要。然而，目前还不清楚到底是哪些化学物质(神经递质)被用来向这些关键部位的神经元传递压力感受性反射信息，以及在这些关键部位的神经元之间传递压力感受性反射信息。在这个项目中，我们将使用最先进的解剖学技术来检查动脉压力感受器反射的神经通路。通过改变血压和专门标记做出反应的神经细胞，我们可以专注于压力感受器反射刺激激活的神经元。集中在已知的影响延髓血压控制的神经递质上，然后我们将在压力敏感神经元周围的神经纤维中标记其中的一个或多个。最后，我们将通过光镜和电子显微镜来确定标记的神经纤维和压力敏感神经元之间的关系。这些关系将显示哪些神经递质可以直接影响压力敏感神经元，哪些间接影响，哪些根本不影响。这个项目将通过澄清哪些神经化学物质在脑干神经元的关键群体中传递压力反射信息来增加我们对压力感受性反射的理解。这些数据将为新的研究奠定基础，这些神经通路的变化是导致体位性低血压等情况下压力反射功能障碍的基础。识别压力反射的递质也可能指向或排除治疗压力反射功能障碍的新药物治疗。

The baroreflex rapidly adjusts arterial blood pressure to meet changing physiological needs. The reflex alters vascular resistance and changes the rate, volume and force at which blood is expelled from the heart, ensuring that organs are adequately supplied with blood-borne nutrients and oxygen. Changes in baroreflex function occur during exercise, correlate with increased mortality and morbidity from heart failure and myocardial infarction and are responsible for postural hypotension in the elderly. Three areas in the brainstem are critical for transmission of the arterial baroreflex. However, it is still not known exactly which chemicals (neurotransmitters) are used to convey baroreflex information to and between neurons in these key sites. In this project, we will use state-of-the-art anatomical techniques to examine nerve pathways that subserve the arterial baroreflex. By changing blood pressure and specifically tagging nerve cells that respond, we can focus on neurons activated by baroreflex stimuli. Concentrating on neurotransmitters known to affect blood pressure control in the medulla, we will then label one or more of these in nerve fibers surrounding the barosensitive neurons. Finally, we will determine by light and electron microscopy the relationships between the labelled nerve fibers and the barosensitive neurons. These relationships will show which neurotransmitters could influence barosensitive neurons directly, which indirectly and which not at all. This project will increase our understanding of the baroreflex by clarifying which neurochemicals convey baroreflex information amongst the key groups of brainstem neurons. These data will form the foundation for new studies on changes in nerve pathways that underlie baroreflex dysfunction in such conditions as postural hypotension. Identifying transmitters for the baroreflex may also point to, or rule out, new drug treatments for disturbances in baroreflex function.