Intermittent hypoxia and hypertension: Role of the lamina terminalis

本研究计划的中心目标是确定中枢神经系统在高血压相关疾病中的作用。 慢性间歇性低氧(CIH)，一种与睡眠呼吸暂停相关的低氧血症模型。我们之前的结果 提示正中视前核参与脑出血所致的持续性高血压。 老鼠。这些实验将研究3种可能使MnPO对CIH做出贡献的新机制 高血压。我们的工作假设是，基于我们之前的研究，CIH触发了FosB转录 涉及血管紧张素II(Ang II)和NO信号的活动增加兴奋导致BDNF驱动的增加 在细胞内的氯化物中。这些效应将进一步增加兴奋性，减少或逆转对 动脉压力感受器在一天的常氧期间促进持续的CIH HTN。 具体目的1：检测血管紧张素信号转导在CIH HTN中MnPO兴奋增加中的作用。 假设：血管紧张素信号的增加增加了下丘脑室旁核投射的MnPO神经元的活性。 目标1将量化脑血管紧张素系统对PVN投射的MnPO活性增加的贡献 神经元使用血管紧张素“嗅觉细胞”19结合光遗传学、膜片钳电生理学，活体 记录交感神经活动和MnPO单位活动。 具体目标2：检测NO在增加CIH HTN中MnPO激发中的作用。 假设：MnPO中NOS1表达和活性增加增加突触前兴奋以驱动 持续的CIH高血压。 目的2将验证假设，即CIH触发的NOS1表达和活性增加 下丘脑室旁核投射MnPO神经元的突触前兴奋。这一机制将在体外进行测试 用碳纤维电极和DAF-2成像对NO的电生理和实时测量 活体记录交感神经活动，用无线电遥测记录慢性血压。 具体目标3：确定减少/逆转的GABA抑制和BDNF对 MnPO兴奋性、突触效能和CIH HTN。 假设：CIH触发BDNF神经元，从而减少/逆转MnPO神经元中GABA的抑制。 目标3将确定BDNF是否减轻/逆转PVN投射的MnPO中GABA对压力感受器的抑制 神经元通过氯化物转运，如钠钾转运体1(NKCC1)和/或 氯化钾共转运蛋白2(KCC2)。这些实验将使用活细胞氯化物成像，脑切片和 在体电生理学和通道视紫红质辅助的电路标测。

The central objective of this research program is to determine the role of the CNS in hypertension associated with chronic intermittent hypoxia (CIH), a model of hypoxemia associated with sleep apnea. Our previous results indicate that the median preoptic nucleus (MnPO) contributes to the sustained hypertension produced by CIH in rat. These experiments will investigate 3 novel mechanisms that may allow the MnPO to contribute to CIH hypertension. Our working hypothesis, based on our previous studies, is that CIH triggers FosB transcriptional activity involving angiotensin II (ANG II) and NO signaling to increase excitation causing BDNF-driven increases in intracellular chloride. These effects would further increase excitation and reduce or reverse inhibition from arterial baroreceptors promoting sustained CIH HTN during normoxic periods of the day. Specific Aim 1: Test the role of angiotensin signaling in increased MnPO excitation in CIH HTN. Hypothesis: Increased angiotensin signaling increases the activity of PVN-projecting MnPO neurons. Aim 1 will quantify the contribution of the brain angiotensin system to increased activity in PVN-projecting MnPO neurons using angiotensin “sniffer cells” 19 combined with optogenetics, patch clamp electrophysiology, in vivo recording of sympathetic nerve activity, and MnPO single unit activity. Specific Aim 2: Test the role of NO in increasing MnPO excitation in CIH HTN. Hypothesis: Increased expression and activity of nos1 in MnPO increases presynaptic excitation to drive sustained CIH hypertension. Aim 2 will test the hypothesis that the increase of nos1 expression and activity triggered by CIH increases presynaptic excitation in PVN projecting MnPO neurons. This mechanism will be tested using in vitro electrophysiology and paired real-time measurements of NO with carbon fiber electrodes and DAF-2 imaging, in vivo recording of sympathetic nerve activity, and chronic blood pressure recording with radio telemetry. Specific Aim 3: Determine the contribution of reduced/reversed GABA inhibition and BDNF to changes in MnPO excitability, synaptic efficacy, and CIH HTN. Hypothesis: CIH triggers BDNF neurons that reduces/reverses GABA inhibition in MnPO neurons. Aim 3 will determine if BDNF reduces/reverses baroreceptor inhibition by GABA in PVN-projecting MnPO neurons though chloride transports such as sodium potassium chloride cotransporter 1 (NKCC1) and/or potassium chloride cotransporter2 (KCC2). These experiments will use live cell chloride imaging, brain slice and in vivo electrophysiology, and channel rhodopsin assisted circuit mapping.