You might recall that microglia immune cells in the brain and nervous system are implicated in the damage of aging. Evolutionary adaptations beneficial in youth come back to bite you in later life, in this case via excessive release of inflammatory cytokines. Researchers are working on ways to deal with that, however: CHPG, an activator of a type of glutamate receptor, "shuts down activation of key immune cells in the brain known as microglia, which sense pathogens or damage in the spinal cord and brain. They helpfully foster the destruction of microbial invaders and clean up biological detritus that occurs after an injury, but researchers say they have a dark side as well ... Under certain conditions, like spinal cord injury and brain trauma, microglia [release] toxic chemicals that can kill healthy adjacent tissue, and this process can continue for months. ... The team had previously found that microglial cells express a certain receptor, the group I metabotropic glutamate receptor 5 (mGluR5), on their surface. Further work showed that if these receptors were specifically activated on microglia, these immune cells would not produce the neurotoxins that led to cell death near the site of injury. CHPG serves to selectively activate the receptor, reducing microglial toxicity."