Glutamate release from satellite glial cells of the murine trigeminal ganglion

• Extracellular glutamate was recorded microfluorimetrically.
• Satellite glial cells released glutamate in response to internal Ca2+ increase.
• Glutamate was released via vesicular exocytosis and via hemichannels.

It has been proposed that glutamate serves as a mediator between neurons and satellite glial cells (SGCs) in sensory ganglia and that SGCs release glutamate. Using a novel method, we studied glutamate release from SGCs from murine trigeminal ganglia. Sensory neurons with adhering SGCs were enzymatically isolated from wild type and transgenic mice in which vesicular exocytosis was suppressed in glial cells. Extracellular glutamate was detected by microfluorimetry. After loading the cells with a photolabile Ca2+ chelator, the intracellular Ca2+ concentration was raised in SGCs by a UV pulse, which resulted in glutamate release. The amount of released glutamate was decreased in cells with suppressed exocytosis and after pharmacological block of hemichannels. The data demonstrate that SGCs of the trigeminal ganglion release glutamate in a Ca2+-dependent manner.