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| Poster #148 Unraveling Geniculate Ganglion and Trigeminal Ganglion Innervation of the Lingual Epithelium |
| Tao Tang1, Debarghya Dutta Banik1, Nicholas Weber2, Suzanne Sollars2, Brian Pierchala11 1Indiana University, Indianapolis, IN, United States 2University of Nebraska at Omaha, Omaha, NE, United States |
Both Geniculate Ganglia (GG) and Trigeminal Ganglia (TG) neurons convey mechanosensory information and innervate the same regions of taste papillae outside of taste buds (TBs). However, the organization of TG versus GG fibers remains unclear. Recent studies identified RET+ neurons in GG and TG that are responsive to stimulation of the tongue surface. The four glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs), GDNF, Neurturin (NRTN), Artemin (ARTN), and Persephin (PSPN), bind to their respective GFR⍺ receptors (GFR⍺1-4) and subsequently activate RET. We found that GFR⍺1 and GFR⍺3, receptors for GDNF and ARTN, are expressed on fibers innervating intragemmal and extragemmal areas of fungiform taste buds. To distinguish between GG or TG originated RET+ fibers in the tongue, we compared the RET+ fibers from Ret-CreER reporter and Ret-CreER; Phox2b-Flpo dual reporter mice (that selectively label RET+ neurons from GG). Nearly all taste buds in Ret-CreER reporter mice had RET+ fibers innervating extragemmal regions, while only 60% of fungiform taste buds had extragemmal fibers labeled in the GG-specific reporter mice. Additionally, we found that Ret-expressing fibers innervate filiform papillae and that GG-fibers innervate many of these. Lastly, to delineate GG and TG contributions to GFR⍺1+ and GFR⍺3+ innervation, we performed unilateral transections of the chorda tympani (GG) and lingual (TG) nerves. Post-transection analysis showed that most GFR⍺3+ fibers within taste buds derive from the GG, whereas extragemmal GFR⍺1+ fibers mainly originate from the TG. In summary, TG and GG neurons exhibit distinct innervation patterns within the lingual epithelium. |