Microinjection of a growth factor cocktail affects activated microglia in the neocortex of adult rats

作     者：Ruo-Xu Liu Jie Ma Ning Guo Shao-Jun Liu Ruo-Xu Liu;Jie Ma;Ning Guo;Shao-Jun Liu

作者机构：State Key Laboratory of Proteomics and Department of Neurobiology Institute of Military Cognition and Brain Sciences 

出 版 物：《Neural Regeneration Research》 (中国神经再生研究（英文版）)

年 卷 期：2020年第15卷第9期

页      面：1709-1715页

核心收录：

学科分类：0710[理学-生物学] 1002[医学-临床医学] 1001[医学-基础医学(可授医学、理学学位)] 100204[医学-神经病学] 100215[医学-康复医学与理疗学] 10[医学] 

基　　金：supported by a grant from State Key Laboratory of Proteomics of China,No.SKLP-K201401(to SJL) the National Key Project of Basic Research of China,No.2009CB918301(to SJL) the National Natural Science Foundation of China,Nos.30430310,30140001,30370460(to SJL) 

主　　题：adult neocortex CD68 IBA1 microinjection phagocyte selective phagocytosis ultrastructure 

摘      要：Microglia, as the resident immune cells in the central nervous system, play important roles in regulating neuronal processes, such as neural excitability, synaptic activity, and apoptotic cell clearance. Growth factors can activate multiple signaling pathways in central nervous system microglia and can regulate their immune effects, but whether growth factors can affect the morphological characteristics and ultrastructure of microglia has not been reported. After microinjecting 300 nL of a growth factor cocktail, including 10 μg/mL epidermal growth factor, 10 μg/mL basic fibroblast growth factor, 10 μg/mL hepatocyte growth factor and 10 μg/mL insulin-like growth factor into adult rat cortex, we found that the number of IBA1-positive microglia around the injection area increased significantly, indicating local activation of microglia. All CD68-positive labeling co-localized with IBA1 in microglia. Cell bodies and protrusions of CD68-positive cells were strongly attached to or were engulfing neurons. Characteristic huge phagosomes were observed in activated phagocytes by electron microscopy. The phagosomes generally included non-degraded neuronal protrusions and mitochondria, yet they contained no myelin membrane or remnants, which might indicate selective phagocytosis by the phagocytes. The remnant myelin sheath after phagocytosis still had regenerative ability and formed myelin-like structures around phagocytes. These results show that microinjection of a growth factor cocktail into the cerebral cortex of rodents can locally activate microglia and induce selective phagocytosis of neural structures by phagocytes. The study was approved by the Institute of Laboratory Animal Science, Beijing Institute of Basic Medical Sciences(approval No. IACUC-AMMS-2014-501) on June 30, 2014.