Laboratory of Neuropharmacology and Neurotoxicology, Shanghai Key Laboratory of Bio-Energy Crops, College of Life Science, Shanghai University, Shanghai, 200444, People's Republic of China.
Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, 200032, People's Republic of China.
J Neuroinflammation. 2017 Aug 23;14(1):169. doi: 10.1186/s12974-017-0942-2.
Neuroinflammation plays hypertensive roles in the uninjured autonomic nuclei of the central nervous system, while its mechanisms remain unclear. The present study is to investigate the effect of neuroinflammation on autophagy in the neurons of the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons for the maintenance of vasomotor tone reside.
Stress-induced hypertension (SIH) was induced by electric foot-shock stressors with noise interventions in rats. Systolic blood pressure (SBP) and the power density of the low frequency (LF) component of the SAP spectrum were measured to reflect sympathetic vasomotor activity. Microglia activation and pro-inflammatory cytokines (PICs (IL-1β, TNF-α)) expression in the RVLM were measured by immunoblotting and immunostaining. Autophagy and autophagic vacuoles (AVs) were examined by autophagic marker (LC3 and p62) expression and transmission electron microscopy (TEM) image, respectively. Autophagy flux was evaluated by RFP-GFP-tandem fluorescent LC3 (tf-LC3) vectors transfected into the RVLM. Tissue levels of glutamate, gamma aminobutyric acid (GABA), and plasma levels of norepinephrine (NE) were measured by using high-performance liquid chromatography (HPLC) with electrochemical detection. The effects of the cisterna magna infused minocycline, a microglia activation inhibitor, on the abovementioned parameters were analyzed.
SIH rats showed increased SBP, plasma NE accompanied by an increase in LF component of the SBP spectrum. Microglia activation and PICs expression was increased in SIH rats. TEM demonstrated that stress led to the accumulation of AVs in the RVLM of SIH rats. In addition to the Tf-LC3 assay, the concurrent increased level of LC3-II and p62 suggested the impairment of autophagic flux in SIH rats. To the contrary, minocycline facilitated autophagic flux and induced a hypotensive effect with attenuated microglia activation and decreased PICs in the RVLM of SIH rats. Furthermore, SIH rats showed higher levels of glutamate and lower level of GABA in the RVLM, while minocycline attenuated the decrease in GABA and the increase in glutamate of SIH rats.
Collectively, we concluded that the neuroinflammation might impair autophagic flux and induced neural excitotoxicity in the RVLM neurons following SIH, which is involved in the development of SIH.
神经炎症在中枢神经系统未受伤的自主神经核中发挥高血压作用，但其机制尚不清楚。本研究旨在探讨神经炎症对维持血管紧张性的延髓头端腹外侧区（RVLM）神经元自噬的影响。
通过电足电击应激与噪声干预诱导应激诱导性高血压（SIH）大鼠。测量收缩压（SBP）和 SAP 谱低频（LF）成分的功率密度，以反映交感血管运动活动。通过免疫印迹和免疫染色测量 RVLM 中的小胶质细胞激活和促炎细胞因子（PICs（IL-1β、TNF-α））表达。通过自噬标记物（LC3 和 p62）表达和透射电子显微镜（TEM）图像分别检查自噬和自噬空泡（AVs）。通过转染 RVLM 的 RFP-GFP 串联荧光 LC3（tf-LC3）载体评估自噬通量。使用高效液相色谱法（HPLC）结合电化学检测测量 RVLM 中的谷氨酸、γ-氨基丁酸（GABA）和血浆中的去甲肾上腺素（NE）水平。分析 cisterna magna 输注米诺环素（一种小胶质细胞激活抑制剂）对上述参数的影响。
SIH 大鼠表现出 SBP 升高，血浆 NE 升高，同时 SBP 谱 LF 成分增加。SIH 大鼠小胶质细胞激活和 PICs 表达增加。TEM 显示，应激导致 SIH 大鼠 RVLM 中 AV 积累。除了 tf-LC3 测定外，LC3-II 和 p62 的同时升高表明 SIH 大鼠自噬通量受损。相反，米诺环素促进自噬通量，并在 SIH 大鼠 RVLM 中引起降压作用，减轻小胶质细胞激活和减少 PICs。此外，SIH 大鼠 RVLM 中的谷氨酸水平升高，GABA 水平降低，而米诺环素减轻 SIH 大鼠 GABA 降低和谷氨酸升高。
总之，我们得出结论，神经炎症可能会损害 SIH 后 RVLM 神经元中的自噬通量并引起神经兴奋性毒性，这与 SIH 的发展有关。
