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Activation of mouse microglial cells affects P2 receptor signaling
T Möller1, O Kann, A Verkhratsky
1Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13122, Berlin-Buch, Germany.
Abstract:
Microglial cells are the immunocompetent cells of the CNS, which are known to exist in several activation states. Here we investigated the impact of microglial activation on the P2 receptor-mediated intracellular calcium ([Ca(2+)](i)) signaling by means of fluo-3 based Ca(2+)-imaging. Cultured mouse microglial cells were treated with either astrocyte-conditioned medium to induce a ramified morphology or LPS to shift the cells toward the fully activated stage. The extracellular application of ATP (100 microM) induced a [Ca(2+)](i) elevation in 85% of both untreated and ramified microglial cells, whereas only 50% of the LPS-activated cells responded to the stimulus. To characterise the pharmacological profile of microglial P2 receptors we investigated the effects of various P2 agonists on [Ca(2+)](i) in cultured microglial cells. Untreated and ramified microglial cells demonstrated a very similar sensitivity to the different P2 agonists. In contrast, in LPS-activated microglia, a sharp decrease of responses to P2 agonist stimulation was seen. This indicates that microglial activation influences the capability of microglial cells to generate [Ca(2+)](i) signals upon P2 receptor activation.
Insights
Microglial activation alters intracellular calcium signaling. Activated microglia show reduced responses to P2 receptor stimulation, impacting their cellular communication pathways.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglial cells are key immune cells in the central nervous system (CNS).
- These cells exist in various activation states, influencing their function.
- P2 receptors play a role in microglial cell signaling.
Purpose of the Study:
- To investigate how microglial activation affects P2 receptor-mediated intracellular calcium ([Ca(2+)](i)) signaling.
- To compare the calcium signaling responses of untreated, ramified, and LPS-activated microglial cells.
Main Methods:
- Utilized fluo-3 based calcium imaging to monitor intracellular calcium levels.
- Cultured mouse microglial cells were treated with astrocyte-conditioned medium or LPS to induce different activation states.
- Applied extracellular ATP and various P2 agonists to assess receptor responses.
Main Results:
- Untreated and ramified microglial cells showed robust calcium elevation in response to ATP.
- LPS-activated microglia exhibited a significantly reduced response to ATP stimulation (50% vs. 85%).
- Pharmacological profiling revealed decreased sensitivity to various P2 agonists in activated microglia.
Conclusions:
- Microglial activation state significantly influences their ability to generate intracellular calcium signals via P2 receptors.
- This altered signaling capability in activated microglia may impact CNS immune responses and neuronal communication.