Gustatory information of umami substances in three major taste nerves

• Published in: Physiology & behavior 2000-10, Vol.71 (1), p.193-198
• Main Authors: Sako, Noritaka, Harada, Shuitsu, Yamamoto, Takashi
• Format: Article
• Language: English
• Subjects: Animals; Behavior, Animal - drug effects; Behavior, Animal - physiology; Biological and medical sciences; Chorda tympani nerve; Chorda Tympani Nerve - physiology; Cranial Nerves - physiology; Electrophysiology; Food Additives - pharmacology; Fundamental and applied biological sciences. Psychology; Glossopharyngeal nerve; Glossopharyngeal Nerve - physiology; Glutamic Acid - pharmacology; greater petrosal nerves; Greater superficial petrosal nerve; Inosine Monophosphate - pharmacology; Male; Olfactory system and olfaction. Gustatory system and gustation; Rats; Rats, Wistar; Taste - physiology; taste transduction; Umami taste; Vertebrates: nervous system and sense organs
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/S0031-9384(00)00342-5

The chorda tympani (CT), glossopharyngeal (GL), and greater superficial petrosal (GSP) nerves, the three major branches of cranial nerves innervating taste buds, respond with considerable differences to various taste stimuli. To examine which nerve is responsible for transmitting umami taste in rats, we conducted electrophysiological and behavioral experiments. In the electrophysiological study, responses to umami substances were compared among these three nerves. The CT and GSP were more responsive to mixtures of monosodium l-glutamate (MSG) and 5′-inosine monophosphate (IMP) than the GL. Synergistic effects by the mixture of MSG and IMP were the most prominent in the CT followed by the GSP, whereas it was negligible in the GL. In the behavioral study, rats with a combined transection of the CT and GSP could not acquire conditioned taste aversions to umami substances. These results suggest that umami taste is conveyed more dominantly via the CT and GSP than the GL in the rat.