Role of Microglia in Parkinson's Disease and Alzheimer's Disease

Microglia cells are the primary immune cells of the central neuron system（CNS), highly similar to peripheral macrophages. They are the major inflammatory cell type in the brain. When they detect pathogens and injury in the brain, they will instantly become activated and migrate to the injured or infected site to destroy pathogens as well as remove damaged cells. And they also secrete cytokines and chemokines, as well as prostaglandins, NO and reactive oxygen species to elevate and direct the immune response. They are instrumental in the resolution of the inflammatory response. Though microglia are known for their protective role in brains, researches have revealed that they can also be harmful to human health. Researchers have been extensively studied for their harmful roles in neurodegenerative diseases, such as Alzheimer’s disease(AD), Parkinson’s disease(PD).

In research on rat microglia , a low systemic dose of rotenone has no impact on young rats, while leading to a 20-30% reduction of dopaminergic neurons in the substantia nigra of older rats. Similar phenomena happen in MPTP-induced dopaminergic neuronal loss in elderly mice, in which more severe and persistent microglia activation are found associated with TH neuronal loss in MPTP-treated elderly rodents. Those results suggest that age-associated microglia over-activation may contribute to the increased sensitivity of dopaminergic neurons to neurotoxins.

In study on another notable age-related neurodegenerative disease AD, microglia are also considered to be a major player in its pathogenesis. Microglia over-activation and dysfunction are also seen in AD brain. Clustering of microglia are usually found around the senile plaques in the aged non-demented and AD brain. Aging microglia are more prevalent in AD brain than age-matched, non-demented brain. Because of their failure to respond to normal regulatory feedback mechanisms or the impairment in their ability to clear Aβ, microglia cells lose ability to handle potentially toxic compounds and thus become cytotoxic. Further investigation of microglia aging or dysfunction in AD may offer a unique approach in probing the microglia biology and thus a new therapeutic direction in preventing and treating AD.

To date, studies have demonstrated that the neuroprotective and neurotoxic characteristics of microglia to dopaminergic neurons are age-dependent. Activated microglia are neuroprotective in the neonatal brain , whereas being neurotoxic in the aged brain. To conclude, microglia senescence that occurs in the aged brain is responsible for the functional alterations and dysregulated responses of microglia. In the aged human brain, a significantly greater area of the substantia nigra is occupied by microglial cell bodies and processes than that of younger subjects. Moreover, the dopaminergic neurons are more sensitive to oxidative stress imposed by microglia than other types of neurons. Thus, increased microglia activation and/or senescenced microglia in the aged brain has put the dopaminergic neurons in a more dangerous environment than that of the young brain.

About Creative Bioarray

Creative Bioarray is the world’s largest primary cells supplier. The company offers 35 human cell systems with over 160 different cell types and also provide primary cells from over 13 types of other animals. We offer both rat microglia.cells and human microglia cells for research use.

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