Decline of umami preference in aged rats

Area of Science:

• Neuroscience
• Sensory Science
• Gerontology

Background:

• Aging impacts sensory perception, including taste.
• Umami taste, mediated by specific receptors, plays a role in appetite and food preference.
• Previous research has not fully elucidated the neural and behavioral changes associated with aging in umami taste perception.

Purpose of the Study:

• To investigate the effects of aging on umami taste preference and neural responses in Sprague Dawley rats.
• To compare behavioral preferences and nerve activity (GSP and CT) to umami stimuli between young and aged rats.
• To determine if age-related changes in umami preference are due to peripheral or central nervous system alterations.

Main Methods:

• Two-bottle preference tests were conducted using umami solutions (IMP, MSG, and mixtures) and deionized water.
• Neural responses were recorded from the greater superficial petrosal (GSP) and chorda tympani (CT) nerves.
• Behavioral preferences and neural activity were compared between young (5-12 weeks) and aged (21-22 months) rats.

Main Results:

• Younger rats showed significant preference for umami solutions over water.
• Aged rats did not exhibit a significant preference for umami solutions compared to water.
• Neural responses from both GSP and CT nerves remained robust in aged rats, indicating intact peripheral taste signaling.
• No significant age-related differences were observed for other basic taste stimuli preferences.

Conclusions:

• The diminished preference for umami taste in aged rats is a central nervous system phenomenon, not a peripheral one.
• Aging-induced homeostatic changes in the brain likely cause the loss of umami taste preference.
• Understanding these age-related taste changes is crucial for addressing nutritional challenges in aging populations.