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Table 2 Effects of enriched environment on microglia

From: Lifestyle-dependent microglial plasticity: training the brain guardians

Species Brain region Experimental paradigm Microglial changes References
Mice Hippocampus, amygdala and hypothalamus EE for 32 and 48 weeks EE reduced expression of pro-inflammatory cytokines, increased Iba1 expression, and induced microglial hypertrophy and increased ramification [79]
Mice Hippocampus EE for 7–8 weeks EE prevents microgliosis induced by human β-amyloid oligomers, as evidenced by morphology, mRNA changes, and brain interstitial fluid cytokine levels [81]
Mice Hippocampus and hypothalamus EE for 6 weeks EE housing blocks pro-inflammatory cytokine gene induction and promotes arginase 1 mRNA expression in brain-sorted microglia, indicating that EE favours an anti-inflammatory activation state [143]
Mice Hippocampus and neocortex EE for 6 weeks EE in APP/PS1 mice amyloidosis model led to improved short-term memory, reduced microgliosis and increased microglial phagocytic activity [83]
Mice   EE for 4–6 weeks EE acting through enhanced β-adrenergic signalling reduces microgliosis in response to direct exposure to β-amyloid [82]
Mice Hippocampus EE, PE, and EE + PE for 7 weeks EE led to an increased microglial number at 5 and 10 months while PE and EE + PE increased microglial numbers only at 10 months [78]
Mice Amygdala EE or PE for 40 days EE Increased microglial proliferation [144]
Rat Hippocampus EE for 12 weeks EE ameliorates cognitive comorbidities associated with type I diabetes mellitus, possibly by reducing hyperactivity in the hypothalamic–pituitary–adrenal axis and microglial reactivity in diabetic animals [91]
Mice Hippocampus EE for 87 weeks Long-term EE reduces microglia morphological diversity of the molecular layer of dentate gyrus [88]
Mice Lateral septum EE for 32 weeks Following dengue infection, EE led to a reduction of microglial morphological diversity [145]
Mice Hippocampus, septum, olfactory bulb and brainstem EE for 16 weeks EE alleviated microgliosis, promoted faster viral clearance, decreased viral dissemination, reduced disease progression, and decreased CNS damage in a model of limbic encephalitis [90]
Mice Hippocampus EE for 12 weeks EE attenuated microgliosis, damage to the extracellular matrix and promoted virus clearance in a model of viral encephalitis [89]
Mice Striatum EE for 7 weeks Glioma-bearing mice housed in EE have increased branching and patrolling activity microglia, besides increased phagocytic activity [92]
Pig Frontal cortex EE for 3 weeks EE piglets displayed a signature consistent with a relative decrease in microglial activity compared to those in the standard condition [146]
  1. EE enriched environment, PE physical exercise, APP/PS1 amyloid precursor protein/presenilin1 mouse Alzheimer's disease model mice