Prostaglandin production in the plerocercoid of Spirometra erinaceieuropaei and its function in larva migrans

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The effects of temperature, pH, and host fatty acids on the fatty acid contents of Spirometra erinaceieuropaei plerocercoids were investigated. After 24 hr incubation at 18ﾟC in host snake serum, omega 6 series fatty acids, especially arachidonic acid, in the phospholipid fraction of the plerocercoids, increased compared with those incubated at 37ﾟC.The change in the ratio of polyunsaturated to saturated fatty acids in the triglyceride fraction was opposite to that observed for the phospholipid fraction after incubation in physiological saline for 6 hr. At 37ﾟC, arachidonic acid in the free fatty acid fraction decreased for the first 3 hr, and increased, at 10ﾟC, however, arachidonic acid in the free fatty acid fraction decreased for the first 1 hr. and increased until 3 hr, and decreased again. The changes of the fatty acid composition of phospholipid and triglyceride fractions in Spirometra eninaceieuropaei plerocercoid were investigated after 0, 0.5, 1, 3, 6 hr with 5 mM arachidonic acid. At 37ﾟC, arachidonic acid was absorbed and incorporated rapidly in triglyceride fraction and decreased after 2-3 hr, but growth slowly at 10ﾟC.In the dose-dependent course, PGD_2 was detected in the plerocercoids incubated with 0.5, 1, 2 and 5 mM arachidonic acid and PGE_2 was detected with 2 and 5 mM arachidonic acid. Total amounts of PGD_2 and PGE_2 increased with increased concentrations of arachidonic acid, and PGF_<2 alpha> and 6-keto-PGF_1 alpha were not detected. In the time-dependent course, PGF_1 alpha was first detected at 15 min, thereafter, 6-keto-PGF_1 alpha a was detected at 30 min and PGD_2 and PGE_2 were detected at 1 hr. Thromboxane B_2 was not detected in either the dose-dependent or time-dependent course, and only PGE_2 were detected in the incubation medium with 5mM arachidonic acid at 1 hr.