The relative effects of transection of the gustatory branches of the seventh and ninth cranial nerves on NaCl taste detection in rats.
Chorda tympani nerve (CT) transection in rats severely impairs NaCl taste detection. These rats can detect higher concentrations of NaCl, however, suggesting that remaining oral nerves maintain some salt sensibility. Rats were tested in a gustometer with a 2-response operant taste-detection task before and after sham surgery (n = 5), combined transection of the CT and the greater superficial petrosal nerves (GSP; 7x, n = 6), or transection of the glossopharyngeal nerve (GL; 9x, n = 4). Thresholds did not significantly change after sham surgery. Although the GL responds to NaCl and innervates nearly 60% of total taste buds, 9x surgery had no effect. However, 7x surgery increased NaCl detection threshold by approximately 2.5 log(10) units, greater than that reported for CT transection alone. These results suggest that the GSP contributes to NaCl sensitivity in rats and also demonstrate that the GL and perhaps the superior laryngeal and lingual nerve proper can maintain some NaCl detectability at high concentrations. These findings confirm the primacy of the 7th nerve relative to the 9th nerve in sensibility of NaCl in the rat model.
Blonde
Ginger D
GD
Department of Psychology and Center for Smell and Taste, University of Florida, Gainesville, FL 32611, USA.
Garcea
Mircea
M
Spector
Alan C
AC
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002814:Chorda Tympani Nerve / Q000293:injuries* / Q000503:physiopathology; D003216:Conditioning, Operant / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology; D004327:Drinking Behavior / Q000502:physiology; D005930:Glossopharyngeal Nerve / Q000503:physiopathology; D061287:Glossopharyngeal Nerve Injuries; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D012965:Sodium Chloride; D013649:Taste / Q000502:physiology*; D013652:Taste Threshold / Q000502:physiology*; D013997:Time Factors
D012965:Sodium Chloride