Parabrachial gustatory neural responses to monosodium glutamate ingested by awake rats.
A sample of 41 gustatory neurons isolated in the parabrachial nuclei of awake, behaving rats was tested with sapid solutions of 0.1 M monosodium glutamate (MSG), 0.5 mM of guanosine 5'-monophosphate (GMP), and a mixture of MSG and GMP as well as with 0.3 M sucrose, 0.1 M NaCl, 0.01 M citric acid, and 0.0001 M QHCl. Interneuronal correlation coefficients and factor analysis indicated that both the sodium cation and glutamic anion contributed to the activity elicited by MSG. Guanosine potentiated the responses to MSG, but only in neurons that also responded to sucrose. These results suggest that the gustatory contribution to the flavor denoted by the Japanese word "umami" may be mediated, in part, by neurons that also respond to chemical described by humans as sweet.
Nishijo
H
H
Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
Ono
T
T
Norgren
R
R
D000818:Animals; D001931:Brain Mapping; D002814:Chorda Tympani Nerve / Q000502:physiology; D005930:Glossopharyngeal Nerve / Q000502:physiology; D006157:Guanosine Monophosphate / Q000502:physiology; D008297:Male; D011149:Pons / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride; D012970:Sodium Glutamate; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000502:physiology*; D013652:Taste Threshold / Q000502:physiology
D012965:Sodium Chloride; D006157:Guanosine Monophosphate; D012970:Sodium Glutamate