Low arachidonic acid rather than alpha-tocopherol is responsible for the delayed postnatal development in offspring of rats fed fish oil instead of olive oil during pregnancy and lactation

This study was designed to compare in rats the effects of dietary fish oil and olive oil during pregnancy and lactation on offspring development, fatt y acid profile and vitamin E concentration. From d 0 of pregnancy, female S prague-Dawley rats were divided into two groups that were fed purified diet s that differed only in their nonvitamin lipid components. One diet contain ed 10 g fish oil/100 g diet (FOD), whereas the other contained 10 g olive o il/100 g diet (OOD). At d 20 of gestation, maternal adipose tissue fatty ac id profile did not differ between rats fed the two diets, whereas both mate rnal and fetal plasma and liver arachidonic acid (AA) contents were proport ionally lower and eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid con tents were higher in the FOD group than in the OOD group, alpha -tocopherol concentration was lower in maternal and fetal plasma, liver and brain in t he FOD group than in the OOD group. The postnatal increase in body weight a nd length was less and body and psychomotor maturation indices were delayed in pups from FOD-fed dams compared with those from GOD-fed darns. This dif ference was maintained when pups were cross-fostered at birth, with the del ay in postnatal development present in the pups suckling darns fed FOD duri ng lactation. At age 21 d, pups suckling dams fed FOD had lower AA and high er EPA and DHA concentrations in brain phospholipids. Although alpha -tocop herol in plasma and liver was lower in pups suckling dams fed FOD rather th an GOD, brain ol-tocopherol concentrations did not differ. Milk yield and m ilk alpha -tocopherol and AA concentrations were lower and EPA and DHA were higher in the milk of dams fed FOD compared with those fed GOD. Postnatal development indices and the proportion of plasma, liver and brain AA concen trations, although not plasma, liver and brain alpha -tocopherol concentrat ions, recovered to the values found in dams fed OOD when the FOD was supple mented with gamma -linolenic acid. However, postnatal development indices w ere not recovered when the FOD was supplemented with sufficient exogenous v itamin E to increase plasma and liver alpha -tocopherol concentrations abov e those in dams fed GOD. Thus, although feeding FOD during pregnancy and la ctation decreases both alpha -tocopherol and AA concentrations, the latter deficiency rather than the former seems to be responsible for delayed postn atal development of rat pups.