Kapoor Komal, Bhandare Amol M, Nedoboy Polina E, Mohammed Suja, Farnham Melissa M J, Pilowsky Paul M
Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales 2109, Australia; The Heart Research Institute, Sydney, New South Wales 2042, Australia.
The Heart Research Institute, Sydney, New South Wales 2042, Australia.
Neuroscience. 2016 Aug 4;329:12-29. doi: 10.1016/j.neuroscience.2016.04.044. Epub 2016 May 4.
Microglia are present throughout the central nervous system (CNS) and express receptors for every known neurotransmitter. During inflammation, microglia change into a state that either promotes removal of debris (M1), or into a state that promotes soothing (M2). Caudal- and rostral- ventrolateral medullary regions (CVLM and RVLM, respectively) of the brainstem are key nuclei involved in all aspects of the cardiovascular system. In this study, we investigate a novel role for microglia in cardiovascular control in the brainstem of adult male Sprague-Dawley (SD) rat. Here we show, that increases and decreases in blood pressure (BP) triggers alertness in the physiology of microglia in the brainstem region; inducing changes in microglial spatial distribution and the number of synapses in contact with microglial end processes. Following 6h of acute hypertension, the number of synapses in contact with microglia increased by ≈30% in both regions of the brainstem, CVLM and RVLM. Induction of acute hypotension for 6h causes microglia to reduce the number of synaptic contacts by >20% in both, CVLM and RVLM, nuclei of the brainstem. Our analysis of the morphological characteristics of microglia, and expression levels of M1 and M2, reveals that the changes induced in microglial behavior do not require any obvious dramatic changes in their morphology. Taken together, our findings suggest that microglia play a novel, unexpected, physiological role in the uninjured autonomic nuclei of CNS; we therefore speculate that microglia act cooperatively with brainstem cardiovascular neurons to maintain them in a physiologically receptive state.
小胶质细胞遍布整个中枢神经系统（CNS），并表达已知的每一种神经递质的受体。在炎症过程中，小胶质细胞会转变为促进清除碎片的状态（M1）或促进舒缓的状态（M2）。脑干的尾侧和头侧腹外侧髓质区域（分别为CVLM和RVLM）是参与心血管系统各个方面的关键核团。在本研究中，我们调查了小胶质细胞在成年雄性Sprague-Dawley（SD）大鼠脑干心血管控制中的新作用。我们在此表明，血压（BP）的升高和降低会触发脑干区域小胶质细胞生理状态的警觉；诱导小胶质细胞空间分布以及与小胶质细胞终末突起接触的突触数量发生变化。急性高血压6小时后，脑干的CVLM和RVLM这两个区域与小胶质细胞接触的突触数量增加了约30%。急性低血压诱导6小时会导致脑干的CVLM和RVLM核团中的小胶质细胞减少突触接触数量超过20%。我们对小胶质细胞形态特征以及M1和M2表达水平的分析表明，小胶质细胞行为的变化并不需要其形态有任何明显的剧烈改变。综上所述，我们的研究结果表明，小胶质细胞在未受损的中枢神经系统自主神经核团中发挥着新的、意想不到的生理作用；因此我们推测，小胶质细胞与脑干心血管神经元协同作用，使其维持在生理接受状态。
