Optical Imaging of Trigeminal Ganglion Excitation Evoked by Electrical Stimulation of the Trigeminal Nerve

Background There are many reports of anatomical and physiological studies on trigeminal ganglion neurons, but few studies have analyzed temporal changes in the excitation of the trigeminal ganglion. This study aimed to establish an experimental system for spatial and temporal imaging analysis of the excitatory dynamics of trigeminal ganglion cells evoked by stimulation of a peripheral branch of the trigeminal nerve. Methods After excision of the trigeminal ganglion with the inferior alveolar nerve (IAN) from Sprague Dawley rats (seven to nine weeks old), 400-µm-thick slices of the trigeminal ganglion with the IAN were prepared. Real-time optical imaging was performed using cell membrane voltage-sensitive dye, Di4-ANEPPS, and changes in fluorescence intensity ratio (ΔF/F) were analyzed. Results Electrical stimulation of the IAN evoked the excitation of the trigeminal ganglion at the lateral surface area first, followed by expansion to the inner area. The calculated conduction velocity was 0.72 ± 0.49 m/s. This response was diminished by tetrodotoxin perfusion, but it was not observed in the C fiber-deficient rats. Conclusions A real-time optical imaging system can visualize the excitation of the trigeminal ganglion evoked by C-fiber stimulation.