Researchers at Stony Brook University have explored the influence of neurosteroids on taste preferences using a laboratory brain model. Their study, published in Current Biology, indicates that elevated levels of neurosteroids within the gustatory cortex can reduce sensitivity and preference for sweet tastes.
Arianna Maffei, a professor in the Department of Neurobiology and Behavior, noted that human studies suggest food preferences impact consumption levels. Reduced taste sensitivity is often linked to overeating, which may contribute to obesity. However, understanding how brain activity affects taste preferences remains challenging due to limitations in current technology for measuring brain activity in humans.
The research team utilized lab mice to investigate neural circuits related to sweet taste preference. They focused on allopregnanolone, a neurosteroid known to be elevated in individuals with obesity. This neurosteroid modulates brain activity by enhancing tonic inhibitory circuits via specific GABA receptors found in excitatory and inhibitory neurons within the gustatory cortex.
By infusing allopregnanolone into the gustatory cortex of mice, researchers activated these GABA receptors, reducing sensitivity and preference for sweet tastes. Using genetic tools to remove these receptors locally further eliminated this preference over water. Maffei explained that removing receptors from inhibitory neurons resulted in mice being unable to distinguish sugared water from plain water.
"This reduced sensitivity and preference for sweet taste was even more prominent if the receptors were selectively removed only from inhibitory gustatory cortex neurons. Indeed, in this case mice were practically unable to distinguish sugared water from water," stated Maffei.
The findings highlight how mammalian brains contribute to taste experiences and identify a crucial signal necessary for sweet taste sensitivity. Ongoing research aims to determine whether neurosteroids affect other tastes or influence eating habits through changes in taste sensitivity.
This research received support from several grants provided by the National Institute for Deafness and Communication Disorder (NIDCD) branch of the National Institutes of Health (NIH), including NIH grants R01DC019827, R01DC013770, R01DC015234, F31 DC019518, and UF1NS115779.
The authors are affiliated with Stony Brook University's College of Arts and Science (Maffei and Priscilla Yevoo) as well as the Renaissance School of Medicine (Alfredo Fontanini).