Changes in food intake and meal patterns following injection of D-mannoheptulose in rats

Behavioral and metabolic effects of intraperitoneal D-mannoheptulose (MH) injections were investigated in rats fed a high carbohydrate (HC) or a high fat (HF) diet. Injection of 125 or 250 mg/kg body weight (body wt) MH did not affect food intake in HC rats. Injection of 400 mg/kg body wt MH inhibited feeding in HC rats by primarily reducing meal size. In contrast, none of the MH doses tested (125, 250, 400, 800 mg/kg body wt) affected food intake or meal patterns in HF rats. The hyperglycemia following MH injection (400 mg/kg body wt) was more pronounced in HC compared to HF rats. MH injection (400 mg/kg body wt) induced a strong taste aversion in HC rats, but had only weak aversive consequences in HF rats. The data throw some doubt on the hypothetical role of insulin in the production of satiety. In addition, the results suggest that a hedonic shift takes place following MH injection in HC rats. The strong dislike for the HC diet after MH injection might be triggered by the severe disturbance of glucose homeostasis and might contribute to the transient hypophagia in HC rats by primarily reducing meal size.