Final answer:
The P2X7 receptor is activated by ATP, leading to the release of pro-inflammatory cytokines by microglia in the context of cell death and inflammation. The correct answer is option a.
Step-by-step explanation:
Microglia, the resident immune cells in the central nervous system (CNS), play a critical role in neuroinflammation, responding to various signals, including ATP released from damaged or dying cells. Among the receptors involved in sensing ATP, the P2X7 receptor stands out for its role in initiating inflammatory responses.
When ATP levels rise due to cellular damage or stress, ATP can bind to and activate P2X7 receptors present on the surface of microglia cells. This receptor is an ion channel activated by ATP, specifically the extracellular ATP, upon binding.
Activation of the P2X7 receptor by ATP induces the influx of calcium ions and triggers the assembly of the NLRP3 (NOD-like receptor family, pyrin domain-containing 3) inflammasome. This inflammasome activation leads to the maturation and release of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). These cytokines contribute to the inflammatory response, recruitment of immune cells, and exacerbation of inflammation in the CNS.
Hence, the P2X7 receptor activation by ATP in microglia plays a pivotal role in initiating the release of pro-inflammatory cytokines, contributing to neuroinflammation and the progression of inflammatory responses in the context of cell death and CNS pathology.