Temporal relationships between eating behavior and liver adenine nucleotides in rats treated with 2,5-AM.

Administration of the fructose analog 2,5-anhydro-d-mannitol (2,5-AM) elicits eating behavior in rats by its action in the liver. To evaluate whether the decrease in liver ATP levels produced by injection of 2,5-AM plays a role in the eating response, we examined the relationship between changes in eating behavior and liver adenine nucleotide levels over time in rats given 2,5-AM. Liver ATP concentrations decreased within 15 min after injection of 2,5-AM (300 mg/kg ip), remained low for up to 90 min postinjection, and returned to control (saline injection) levels by 4 h after treatment. Rats fed ad libitum initiated eating between 15 and 45 min after 2,5-AM treatment, after liver ATP levels had declined. Rats given food 1 h after 2,5-AM treatment increased food intake, but if access to food was delayed for 4 h after 2,5-AM injection the eating response was attenuated or absent. Whereas liver AMP and ADP levels were also altered by injection of 2,5-AM, changes in food intake did not consistently track changes in these nucleotides. The results support the hypothesis that the eating response to 2,5-AM is triggered by a decrease in liver ATP level.