The effects of food restriction on metabolism and accumulation of pentachlorobenzene (PECB), and on hepatic drug-metabolizing enzyme activities were investigated in rats.
After oral administration of PECB (15mg) rats were fed on restricted diets (0%, 25% or 50% of ad libitum amount) for 8 days. Fat tissue weight was significantly decreased by restricted feeding. The concentrations of PECB and pentachlorophenol, a major metabolite of PECB, in blood of the restricted feeding groups were higher at day 2 and day 4 than those of the ad libitum group. At the end of the experiment, the contents of PECB in blood, liver, kidney, brain and fat tissue of the restricted feeding groups were significantly lower than those of the ad libitum group. The increase of PECB metabolism in the restricted feeding groups could not be explained only by changes of hepatic drug-metabolizing enzyme activities. These results suggested that the restricted feeding decreased the weight of fat tissue, the major accumulation site of PECB, so the PECB concentration available to hepatic drugmetabolizing enzymes increased and the amount of PECB metabolite formed was increased.