Mouse study finds fructose sends weaker fullness signal than glucose
Monell researchers report that fructose and glucose use different gut-brain routes, shaping hunger signals and sugar preferences in mice.
By Priya Raghavan · Science Reporter
3 min read
Fructose appears to tell the brain less strongly than glucose that calories have arrived, according to a mouse study from the Monell Chemical Senses Center. The finding may help explain how different sugars influence appetite-related brain circuits and food preferences, despite carrying the same number of calories.
The research, published in Neuron, examined how fructose and glucose communicate from the gut to the brain. Monell researchers reported that fructose uses a specific gut-brain pathway that only modestly reduces the activity of neurons linked to hunger, while glucose produces a stronger response through a different route.
Amber Alhadeff, a Monell member and senior author of the study, said the work adds to researchers’ understanding of how diets high in fructose or high-fructose corn syrup interact with neural systems involved in appetite.
Different sugars, different signals
The team recorded neural activity in mice after the animals received the sugars. According to Monell, fructose raised levels of the gut hormone PYY, which then signaled through the vagus nerve and modestly inhibited agouti-related protein neurons, known as AgRP neurons.
Those neurons are brain cells involved in promoting hunger. When researchers disrupted the PYY-Y2 vagus nerve pathway, fructose no longer had the same effect on AgRP neuron activity, the team reported.
Glucose did not depend on that same pathway, according to the study. Monell researchers said glucose caused a much stronger reduction in AgRP neuron activity than fructose did.
The distinction matters because AgRP neurons have often been treated as cells that respond to calorie intake broadly. The new work suggests these neurons can distinguish among nutrient types and respond through separate biological pathways, according to the researchers.
Preferences followed brain response
The researchers also studied how the different neural responses related to feeding behavior. Monell reported that fructose and glucose produced similar short-term effects on the amount of food the mice consumed.
Over time, however, the animals developed preferences tied to the degree of AgRP inhibition associated with each sugar, according to the study. The finding links nutrient-specific brain signaling with later choices, although the work was conducted in mice.
The team also tested high-fructose corn syrup, a common additive made from a mixture of fructose and glucose. The mice preferred high-fructose corn syrup, and it reduced AgRP neuron activity more strongly than fructose alone, Monell reported.
The researchers said that stronger response may help explain why foods and drinks containing high-fructose corn syrup can be especially appealing to some people. The study did not report that the mouse findings prove the same mechanism drives human preference.
A closer look at nutrient sensing
The paper, titled “Attenuated hypothalamic response to fructose via a dedicated gut-brain pathway,” was authored by Aaron D. McKnight and colleagues and published in Neuron. Its DOI is 10.1016/j.neuron.2026.05.013.
Monell said the results point to a more complex view of nutrient sensing than a simple calorie-counting model. In the study, two sugars with equal caloric content produced different gut hormone signals, different neural responses and different links to preference in mice.
This story draws on original reporting from Medical Xpress.