Taste preference changes throughout different life stages in male rats

• Published in: PloS one Vol. 12; no. 7; p. e0181650
• Main Authors: Inui-Yamamoto, Chizuko, Yamamoto, Takashi, Ueda, Katsura, Nakatsuka, Michiko, Kumabe, Shunji, Inui, Tadashi, Iwai, Yasutomo
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.07.2017; Public Library of Science (PLoS)
• Subjects: Age; Aging; Aging (artificial); Aging - physiology; Aging - psychology; Animals; Behavior; Biology and Life Sciences; Central nervous system; Chorda tympani; Chorda Tympani Nerve - physiology; Diabetes; Electrophysiology; Food; Food habits; Gastrointestinal system; Low concentrations; Male; Medicine and Health Sciences; Middle age; Nerves; Nervous system; Neurosciences; Older people; People and Places; Physical Sciences; Physiological aspects; Preferences; Quinine; Rats; Rats, Sprague-Dawley; Research and Analysis Methods; Rodents; Social Sciences; Sodium Chloride; Studies; Sucrose; Sugar; Taste; Taste (Sense); Taste - physiology; Taste preferences; Taste stimuli; Taste thresholds; Weaning; Young adults; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0181650

Taste preference, a key component of food choice, changes with aging. However, it remains unclear how this occurs. To determine differences in taste preference between rats in different life stages, we examined the consumption of taste solutions and water using a two-bottle test. Male Sprague-Dawley rats of different ages were used: juvenile (3-6 weeks), young adult (8-11 weeks), adult (17-20 weeks), middle-aged (34-37 weeks), and old-aged (69-72 weeks). The intakes of the high and low concentration solutions presented simultaneously were measured. We observed that the old-aged group had lower preference ratios for 0.3 M sucrose and 0.1 M MSG in comparison with other groups. The preference ratio for 0.03 mM QHCl was higher in the middle-aged group than in the three younger groups and higher in the old-aged group than the juvenile group. The taste preferences for HCl and NaCl did not significantly differ among the age groups. The old-aged group tended to prefer high concentrations of sucrose, QHCl, NaCl, and MSG to low concentrations, indicating age-related decline in taste sensitivity. We also aimed to investigate differences between life stages in the electrophysiological responses of the chorda tympani nerve, one of the peripheral gustatory nerves, to taste stimuli. The electrophysiological recordings showed that aging did not alter the function of the chorda tympani nerve. This study showed that aging induced alterations in taste preference. It is likely that these alterations are a result of functional changes in other peripheral taste nerves, the gastrointestinal system, or the central nervous system.