Fish oil enhances pentachlorobenzene metabolism and reduces its accumulation in rats.

To investigate the influence of dietary fats on the metabolism and excretion of pentachlorobenzene (PECB), rats were fed semipurified diets containing soybean oil, lard or fish oil (10 g/100 g diet) for 2 wk. Rats then received a single dose of PECB by intragastric gavage. Blood concentration of pentachlorophenol (PCP), a major metabolite of PECB, was higher after 5 h through d 3 and that of PECB was lower after d 5 in the rats fed fish oil than in rats fed the other fats. After d 5, the highest ratio of PCP/PECB in the liver was seen in the fish oil-fed rats. Furthermore, fish oil intake resulted in a markedly lower concentration of PECB in fat tissues, where a large amount of PECB is typically distributed due to its lipophilic property. These findings indicate that fish oil feeding enhances PECB metabolism, thereby decreasing PECB residues in the body. Fish oil-fed rats had a smaller epididymal fat tissue mass compared with lard- or soybean oil-fed rats. The small mass of the fat tissues apparently limited the accumulation of PECB in those tissues and thus accelerated PECB metabolism in the liver.