Table 2.

Behavior of microglia in different conditions

Conditions	Microglia function
In steady state
Healthy resting state	Surveillance, homeostasis [85] Fixed cell and motile processes, minimal expression of cell surface markers and release of cytokines and chemokines, not involved in Phagocytosis
In disease state
Neuroprotective
Axotomy of the optic nerve	Efficient clearance of myelin debris [41]
Traumatic injury	Clear glutamate without evoking inflammatory mediators [44]
Ischemia	Synthesis of tumor necrosis factor, engulfment of harmful invading neutrophil granulocytes [86]
Alzheimer’s Disease	Internalize and degrade amyloid beta [87]
Multiple sclerosis	Secrete soluble mediators that trigger neural repair and usually contribute to the creation of an environment conductive for regeneration [48]
Neurotoxic
Parkinson’s disease	Releasing various kinds of noxious cytokines, reactive oxygen species [88]
Multiple sclerosis	Express iNOS [89] and generate toxic ROS which might injure neurons
Alzheimer’s disease	Produce of chemokines, neurotoxic cytokines and reactive oxygen an dnitrogen species that are deletrious to the CNS [90]