When the chorda tympani nerve is sectioned, expression of brain-derived neurotrophic factor (BDNF) remains high in the geniculate ganglion and lingual epithelium, despite the loss of taste buds.
The following data were determined for all the volunteers: alimentary frequency by clinical dieticians; genotyping of the G145C polymorphism in the TAS2r38 gene; cognitive status; sensorial (visual and hearing) acuity and drugs related to ageusia or dysgeusia.
Reverse transcriptase polymerase chain reaction and immunohistochemistry showed expression of tas1r1, tas1r3, and alpha-gustducin in fungiform papillae in all 12 subjects tested, including subjects who presented specific ageusia for glutamate.