Related Experiment Video
Updated: Jun 21, 2026

Assessing Retinal Microglial Phagocytic Function In Vivo Using a Flow Cytometry-based Assay
Published on: October 18, 2016
P2Y(6)-Evoked Microglial Phagocytosis
Kazuhide Inoue1, Schuichi Koizumi, Ayako Kataoka
1Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka 812-8582, Japan.
Abstract:
While it was reported that microglia is engaged in the clearance of dead cells or dangerous debris, the mechanism of phagocytosis is still unclear. Recently, we found that purinergic system has a very important role for the chemotaxis and phagocytosis of microglia. When neighboring cells are injured, the cells release or leak ATP into extracellular space and microglia rapidly move toward or extend a process to the nucleotides as chemotaxis through P2Y(12) receptors of microglia. In the meanwhile, microglia expressing metabotropic P2Y(6) receptors show phagocytosis by the stimulation of uridine 5'-diphosphate (UDP), an agonist of P2Y(6). UDP/UTP is leaked when hippocampal neurons are damaged by kainic acid (KA) in vivo and in vitro. Systemic administration of KA in rats results in neuronal cell death in the hippocampal CA1 and CA3 regions, where mRNA for P2Y(6) receptors increases activated microglia. Thus, the P2Y(6) receptor is upregulated when neurons are damaged, and would function as a sensor for phagocytosis by sensing diffusible UDP signals.
Insights
Microglia use the purinergic system for cell clearance. P2Y(6) receptors sense signals like uridine 5'-diphosphate (UDP) released from damaged neurons, enabling microglia phagocytosis.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are crucial for clearing cellular debris, but their phagocytosis mechanisms remain incompletely understood.
- The purinergic system, involving extracellular nucleotides, plays a significant role in microglial functions.
Purpose of the Study:
- To elucidate the role of the purinergic system in microglial chemotaxis and phagocytosis.
- To investigate the specific receptors and signaling molecules involved in microglia's response to neuronal damage.
Main Methods:
- Investigated microglial chemotaxis and phagocytosis in response to extracellular nucleotides.
- Utilized in vivo and in vitro models of neuronal damage induced by kainic acid (KA).
- Analyzed changes in P2Y(6) receptor mRNA expression in activated microglia within the hippocampus.
Main Results:
- Microglia exhibit chemotaxis towards extracellular ATP via P2Y(12) receptors.
- Microglia demonstrate phagocytosis stimulated by uridine 5"-diphosphate (UDP) through P2Y(6) receptors.
- Kainic acid-induced hippocampal neuronal damage leads to the release of UDP/UTP and upregulation of P2Y(6) receptor mRNA in activated microglia.
Conclusions:
- The P2Y(6) receptor acts as a critical sensor for diffusible UDP signals released during neuronal injury.
- Upregulation of P2Y(6) receptors facilitates microglial phagocytosis of damaged neuronal debris.
- The purinergic system is essential for mediating microglial responses to central nervous system damage.
Related Concept Videos
Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
Phagocytosis
The objective of phagocytosis is often destruction. Cells use phagocytosis to eliminate unwelcome visitors, like pathogens (e.g., viruses and bacteria). Many immune system cells, including...
Phagocytosis
Phagocytosis of Apoptotic Cells
Normal cells contain receptors that prevent them from being recognized by phagocytes.

