title: Decline of umami preference in aged rats.
abstract: The effects of aging on the umami sensation were compared between the preference and neural responses from the greater superficial petrosal nerve (GSP innervating the soft palate) and the chorda tympani nerve (CT innervating the fungiform papillae) in the Sprague Dawley rat. A two-bottle preference test revealed that younger rats (5-12 weeks) preferred significantly 0.001 M 5'-inosine monophosphate (IMP), 0.01 M mono sodium glutamate (MSG), and binary mixtures of 0.001 M IMP+0.01 M MSG than deionized water. However, aged rats (21-22 months) showed no significant preference to these umami solutions compared to deionized water. Among the other four basic taste stimuli, there were no significant differences in preference between young and aged rats. Regardless of the age of the rat, neural responses from the GSP and CT produced robust integrated responses to all three umami solutions used in the two-bottle tests. These results indicate that the lack of preference to umami in aged rats is a central nervous system phenomenon and suggests that the loss of preference to umami taste in aged rats is caused by homeostatic changes in the brain incurred by aging.
authors.affiliation: Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan. Electronic address: hmiura@dent.kagoshima-u.ac.jp.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Miura
authors.affiliation: Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ooki
authors.affiliation: Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Norikazu
authors.initials: N
authors.lastname: Kanemaru
authors.affiliation: Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Shuitsu
authors.initials: S
authors.lastname: Harada
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D002814:Chorda Tympani Nerve / Q000502:physiology*; D005518:Food Preferences; D007291:Inosine Monophosphate / Q000494:pharmacology*; D008297:Male; D010160:Palate, Soft / Q000294:innervation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012970:Sodium Glutamate / Q000494:pharmacology; D013649:Taste / Q000187:drug effects* / Q000502:physiology*; D014059:Tongue / Q000294:innervation
chemical_list: D007291:Inosine Monophosphate; D012970:Sodium Glutamate
keywords: Aging; Sweet; Taste nerve responses; Taste preference; Umami