Effect of Eveing Primrose on Plasma Cholesterol Levels and Immune Response to Sheep Erythrocytes

ABSTRACT

Evening primrose oil(EPO), which contains 72% cis-linoleic acid and 9% cisgamma linolenic acid, has been clinically used for treatment of number of diseases in human and animals. And it is also known to lower cholesterol(CHO) level of hypercholesterolaemic individuals. But the role of EPO as CHO-suppressant is controversial, and the relationship of EPO to CHO level in immune regulating activities is unclear at present. To evaluate the effect of evening primrose on the normal plasma CHO-levels, rabbits were fed with evening primrose seed(EPS) or injected with evening primrose seed-extract(EPE), and measured the plasma CHO-levels by duration of treatment. Both of EPS and EPE did not influence the plasma CHO-levels until 4 day treatment and thereafter the levels were significantly reduced. For the investigation of the EPE-effect on immune response to sheep erythrocytes(SRBC), mice were injected with EPE for 4 days before SRBC-sensitization or with CHO just before SRBC, Sensitization or with CHO in regulating effect of immune response was evaluated by the measuring the footpad swelling reaction and antibody response to SRBC. EPE itself did not influence Arthus reaction but it remarkable reduced delayed type hypersensitivity(DTH) and antibody production in comparison with control. CHO slightly increased Arthus reaction and DTH, but it somewhat decreased antibody responses. However, CHO significantly recovered the EPE-induced decrement of DTH and humoral immunity. There results led to that conclusion the evening primrose triggers the decrease of plasma CHO-levels and immune responses, and suggested that the mechanisms responsible for the nonspecific immune inhibitory effect of evening primrose might be partially due to the decrement of the CHO-levels.