Elucidation of neuronal activity in mouse models of TMJ injury byin vivoGCaMP Ca2+imaging of intact trigeminal ganglion neurons

Abstract

AbstractPatients with temporomandibular disorders (TMD) typically experience facial pain and discomfort or tenderness in the temporomandibular joint (TMJ), causing disability in daily life. Unfortunately, existing treatments for TMD are not always effective, creating a need for more advanced, mechanism-based therapies. In this study, we usedin vivoGCaMP3 Ca2+imaging of intact trigeminal ganglia (TG) to characterize functional activity of the TG neuronsin vivo, specifically in TMJ animal models. This system allows us to observe neuronal activity in intact anatomical, physiological, and clinical conditions and to assess neuronal function and response to various stimuli. We observed a significant increase in spontaneously and transiently activated neurons responding to mechanical, thermal, and chemical stimuli in the TG of forced mouth open (FMO) mice. An inhibitor of the CGRP receptor significantly attenuated FMO-induced facial hypersensitivity. In addition, we confirmed the attenuating effect of CGRP antagonist on FMO-induced sensitization byin vivoGCaMP3 Ca2+imaging of intact TG. Our results contribute to unraveling the role and activity of TG neurons in the TMJ pain animal models of TMD, bringing us closer understanding the pathophysiological processes underlying TMD. Our study also illustrates the utility ofin vivoGCaMP3 Ca2+imaging of intact TG for studies aimed at developing more targeted and effective treatments for TMD.