In vivo imaging of brain metabolism activity using a phosphorescent oxygen-sensitive probe

• We tested the in vivo cell-penetrating phosphorescent oxygen-sensitive probe NanO2-IR.
• A phosphorescent signal was recorded in the barrel field of the somatosensory cortex.
• Whisker stimulation led to changes in oxygenation in the barrel field.
• The oxygenation data were compared to those produced using voltage-sensitive dye.

Several approaches have been adopted for real-time imaging of neural activity in vivo. We tested a new cell-penetrating phosphorescent oxygen-sensitive probe, NanO2-IR, to monitor temporal and spatial dynamics of oxygen metabolism in the neocortex following peripheral sensory stimulation. Probe solution was applied to the surface of anesthetized mouse brain; optical imaging was performed using a MiCAM-02 system. Trains of whisker stimuli were delivered and associated changes in phosphorescent signal were recorded in the contralateral somatosensory (“barrel”) cortex. Sensory stimulation led to changes in oxygenation of activated areas of the barrel cortex. The oxygen imaging results were compared to those produced by the voltage-sensitive dye RH-1691. While the signals emitted by the two probes differed in shape and amplitude, they both faithfully indicated specific whisker evoked cortical activity. Thus, NanO2-IR probe can be used as a tool in visualization and real-time analysis of sensory-evoked neural activity in vivo.