Photopharmacological modulation of hippocampal local field potential by caged‐glutamate with MicroLED probe

Aim Photopharmacology is a new technique for modulating biological phenomena through the photoconversion of substances in a specific target region at precise times. Caged compounds are thought to be compatible with photopharmacology as uncaged ligands are released and function in a light irradiation‐dependent manner. Here, we investigated whether a microscale light‐emitting diode (MicroLED) probe is applicable for the photoconversion of caged‐glutamate (caged‐Glu) in vivo. Methods A needle‐shaped MicroLED probe was fabricated and inserted into the mouse hippocampal dentate gyrus (DG) with a cannula for drug injection and a recording electrode for measuring the local field potential (LFP). Artificial cerebrospinal fluid (ACSF) or caged‐Glu was infused into the DG and illuminated with light from a MicroLED probe. Results In the caged‐Glu‐injected DG, the LFP changed in the 10–20 Hz frequency ranges after light illumination, whereas there was no change in the ACSF control condition. Conclusion The MicroLED probe is applicable for photopharmacological experiments to modulate LFP with caged‐Glu in vivo.