Galactose consumption induces conditioned flavor avoidance in rats

Area of Science:

• Neuroscience and Behavior
• Nutritional Science
• Gastroenterology

Background:

• Previous research indicated that intragastric galactose infusions induced flavor avoidance in rats.
• The current study aimed to clarify if oral galactose consumption also elicits learned aversions.

Purpose of the Study:

• To investigate the flavor conditioning effects of orally consumed galactose in food-restricted rats.
• To determine if galactose has aversive postingestive consequences independent of the administration method.

Main Methods:

• Rats were trained to consume flavored solutions containing galactose (with saccharin for palatability), fructose, or saccharin alone.
• Two-bottle choice tests evaluated pre- and posttraining preferences for sugar solutions and flavors.
• Experiments utilized varying concentrations of galactose, fructose, and glucose.

Main Results:

• Rats significantly reduced their preference for the galactose-paired flavor from 76% to 19% post-training (P < 0.01).
• A significant avoidance (P < 0.05) of the galactose-associated flavor was observed in choice tests.
• Preference reversals were consistently observed across multiple experimental conditions and concentrations.

Conclusions:

• Orally consumed galactose, even at low concentrations (20 g/L), induces aversive postingestive consequences and flavor avoidance in rats.
• This learned aversion is likely due to slow and incomplete postabsorptive metabolism of galactose, distinct from lactose intolerance mechanisms.