Investigating the Plasticity of Innervation and Synaptic Specialization Within the Mouse Taste Bud

The peripheral gustatory system is constantly renewing and rewiring itself. We now know more about the molecular and cellular processes involved in taste receptor cell turnover and differentiation, but many questions remain about how taste synapses are formed and reconnected during this process. Recent studies have identified specific proteins that target to the presynaptic membrane of the taste receptor cell. This provides an opportunity to visualize and monitor these presynaptic sites in situ. For my thesis project, I have established protocols to immunostain different presynaptic proteins within taste receptor cells along with the gustatory nerve fibers that innervate the taste buds. I demonstrated that these pre-synaptic proteins co-localize with gustatory neurons, supporting that these are likely synaptic partners. Then, to determine if innervation is necessary for organizing the presynaptic structure, I performed unilateral axotomy to induce denervation of the taste buds. Preliminary results show a decrease of presynaptic puncta ipsilateral to the lesion compared to the intact side. Finally, by optimizing tissue clearing techniques and light sheet microscopy, I obtained a high-resolution three-dimensional rendering of a mouse tongue with td-tomato labeled gustatory nerve fibers. By combining these new techniques, we could potentially locate presynaptic sites while preserving the global morphology of the tongue, demonstrating with high precision the synaptic sites between the taste receptor cell and the afferent nerve, providing better understanding of the relationship between synaptic partners.