Dietary fish oil affects monoaminergic neurotransmission and behavior in rats

We studied the effects of a fish oil enriched diet on fatty acid compositio n of cerebral membranes and on several neurochemical and behavioral variabl es of monoaminergic function in rats. The frontal cortex, striatum, hippoca mpus and cerebellum were studied in rats fed fish oil (FPO, 50% salmon oil + 50% palm oil), which provided an (n-6)/(n-3) polyunsaturated fatty acid ( PUFA) ratio of 0.14 versus 6.19 in controls fed a diet containing a mixture of African peanut oil and rapeseed oil. In the FPO group compared to the c ontrol group, the major modifications in fatty acid composition of cerebral membranes included the following: higher levels in 22:6(n-3), lower levels in 20:4(n-6) and a significantly greater proportion of phosphatidylserine, Dopamine levels were 40% greater in the frontal cortex of rats fed FPO tha n from those fed the control diet. In this cerebral region there was also a reduction in monoamine oxidase B (MAO-B) activity and greater binding to d opamine D-2 receptors. By contrast, a lower binding to dopamine D-2 recepto rs (-7%) was observed in the striatum. Ambulatory activity was also reduced in FPO-fed rats, possibly related to observed changes in striatal dopamine rgic receptors. This suggested that the level of (n-6) PUFA, which was cons iderably lower in the FPO diet than in the control diet, could act on locom otion through an effect on striatal dopaminergic function, whereas the high level of (n-3) PUFA could act on cortical dopaminergic function.