Evaluation of a subchronic (13-week) oral toxicity study, preceded by an in utero exposure phase, with arachidonic acid oil derived from Mortierella alpina in rats

Arachidonic acid oil (ARA-oil) derived from the fungus Mortierella alpina f or use in infant nutrition was tested in a subchronic (13-seek) oral toxici ty study in rats, preceded by an in utero exposure phase. The ARA-oil was a dministered as admixture to the rodent diet at dose levels of 3000 ppm, 15, 000 ppm and 75,000 ppm. An additional high-dose group received 75,000 ppm A RA-oil in combination with 55,000 ppm fish oil containing docosahexaenoic a cid (DHA), at a ratio of ARA to DHA, comparable to the ratio in mother's mi lli of 2:1. The total levels of fat in each diet were kept constant by addi ng the appropriate amounts of corn oil. 12 concurrent control group receive d 130,000 ppm corn oil in the diet. An additional carrier control group was fed unsupplemented rodent diet. Administration of the test substances from 4 weeks prior to mating, throughout mating, gestation, lactation of parent al (F-0) animals acid weaning of the F-1 pups did not affect fertility or r eproductive performance, nor the general condition of pups, viability, sex ratio or number of pups. Pup weight gain in the ARA/DHA-oil group was lower than the controls administered equal amounts of corn oil. In the subsequen t subchronic study survival, clinical signs, body weight gain and food cons umption were not adversely affected by the test substances. Ophthalmoscopic examination did not reveal any treatment-related changes, There were no tr eatment-related effects observed up to dietary test substance concentration s of 15,000 ppm. The following statistically significant differences were f ound in the ARA high-dose group and /or in the ARA/DHA group compared to th e corn oil control group: decreased alkaline phosphatase activity. decrease s in cholesterol, triglycerides and phospholipids concentrations, increased creatinine and urea concentrations. Furthermore, these groups showed incre ased adrenal, spleen and liver weights. The incidence of hepatocellular vac uolation was increased in females of the ARA high-dose group and the ARA/DH A group. Oil droplets were observed in the mesenteric lymph nodes and in th e intestinal villi in the ARA high-dose group and the ARA/DHA group. In add ition, lipogranulomas were observed in the mesenteric lymph nodes in these groups. The observed changes in the high-dose groups may be effects of the high intake of high-fat Itt,els, rather than specific effects of the ARA-oi l. The no-observed-effect level in this study was placed at 15,000 ppm ARA- oil. This level is equivalent to approximately 970 mg ARA-oil/kg body weigh t/day. (C) 2000 Elsevier Science Ltd. All rights reserved.