Abstract
The involvement of adipose tissue in the metabolism and the accumulation of pentachlorobenzene (PECB) was investigated in 4-week-old rats (4WK) or 6-week-old rats (6WK) and 13-week-old rats (13WK). Adipose tissue weight, especially perirenal adipose tissue, in 4WK and 6WK was much smaller than that in 13WK (10-20% of 13WK). When a single dose of PECB was orally administered to the rats, the decrease of PECB and the increase of pentachlorophenol (PCP), a major metabolite of PECB, in blood were remarkable in 4WK and 6WK compared with those in 13WK. After a 6-day PECB administration, the ratio of PCP/PECB in liver was higher and PECB residues in liver, kidney, brain and adipose tissue were lower in 4WK than those in 13WK. The content of hepatic cytochrome P-450, which could metabolize PECB to PCP, was significantly lower in 4WK. These results suggested that a small adipose tissue content in 4WK greatly influenced the metabolism of PECB by increasing the concentration of substrate (PECB) for hepatic drug-metabolizing enzymes. The increases of serum GPT and liver weight due to a 6-day PECB administration were marked in 4WK, suggesting that 4WK is susceptible to the effect of PECB compared with 13WK.
