Interrelationships between energy and fat metabolism and hypophagia in rats treated with perfluorodecanoic acid

Energy metabolism and body composition were investigated in perfluorodecanoic acid (PFDA)-treated rats (single i.p. dose of 20, 40 or 80 mg/kg) and their respective pair-fed counterparts 7 days after dosing. Cumulative feed intake and body weight were decreased in a dose-dependent manner. However, PFDA-treated rats either gained less weight or lost more weight (dependent on the dose administered) than their pair-fed, vehicle-treated counterparts, even though feed intake in these two treatment groups was similar. Energy expenditure, determined indirectly by quantifying oxygen consumption and carbon dioxide production, decreased in a dose-dependent fashion, yet it was similar in PFDA-treated rats and their pair-fed counterparts at a given dose. Body composition analysis indicated a dose-dependent decrease in carcass water and protein content in both PFDA-treated rats and pair-fed partners, while total amount of ash remained unchanged in all treatment groups. These alterations in body composition are compatible with a negative energy balance. Even though PFDA-treated rats had a lower body weight than their pair-fed counterparts at each dose level, they were found to have a greater carcass fat content. Thus, at maintenance (i.e., zero change of body weight) PFDA-treated rats require a higher caloric intake associated with a greater body fat content than vehicle-treated animals.