Decline of umami preference in aged rats

• Published in: Neuroscience letters Vol. 577; pp. 56 - 60
• Main Authors: Miura, Hirohito, Ooki, Makoto, Kanemaru, Norikazu, Harada, Shuitsu
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 08.08.2014
• Subjects: Age Factors; Aging; Animals; Chorda Tympani Nerve - physiology; Food Preferences; Inosine Monophosphate - pharmacology; Male; Palate, Soft - innervation; Rats; Rats, Sprague-Dawley; Sodium Glutamate - pharmacology; Sweet; Taste - drug effects; Taste - physiology; Taste nerve responses; Taste preference; Tongue - innervation; Umami; Aging; Sweet; Umami; Taste preference; Taste nerve responses
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2014.06.018

•Neural responses to both sweet and umami taste did not differ between young and aged rats.•Preference for umami taste markedly declined in aged rats.•Preference for sweet taste was maintained in aged rats.•Aging affects central mechanisms of taste preferences for umami. 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 0.001M 5′-inosine monophosphate (IMP), 0.01M mono sodium glutamate (MSG), and binary mixtures of 0.001M IMP+0.01M 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.