The release of prostaglandin E2 from the skin of the plaice, Pleuronectes platessa L.

1 A fungal extract which produces a cutaneous hypersensitivity reaction in the plaice, Pleuronectes platessa L., was incubated in vitro with the skin of this teleost fish. Samples of incubation media were assayed for smooth muscle stimulating activity. 2 Prostaglandin E2 was identified by bioassay, thin-layer chromatography, ultraviolet absorption spectroscopy and gas chromatography--mass spectrometry. Release from challenged skin was maximum after 60 min incubation. 3 Analysis of the fatty acid composition of plaice skin showed that although arachidonic acid was present (3% of total fatty acids), the precursor of prostaglandin E3, eicosapentaenoic acid contributed 9% of total. 4 Indomethacin (50 mg/kg i.p) did not inhibit the erythema induced by the fungal extract, whilst a dose of 1 mg/kg maximally inhibited prostaglandin release from skin on incubation in vitro. 5 It is concluded that prostaglandins do not have an exclusive role in the mediation of the hypersensitivity reaction.