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Title: Distribution and function of lipoxins and other eicosanoids in the rainbow trout, Oncorhynchus mykiss
Author: Knight, J.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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The eicosanoids are a group of biologically active fatty acids derived from C20 eicosanoic precursors. The eicosanoid generating capabilities of calcium ionophore stimulated rainbow trout peripheral blood cells and solid tissue were examined. Adherent leucocytes (monocytes/granulocytes) generated a plethora of eicosanoids including prostaglandins (PG), monohydroxy eicosatetraenoic acids (HETEs), monohydroxy eicosapentaenoic acids (HEPEs), lipoxins (LX), leukotrienes (LT) and other diHETEs/diHEPEs. Thrombocytes displayed a similar eicosanoid profile, and in addition, were also prolific generators of thromboxanes. Purified lymphocytes generated only trace amounts of lipoxygenase products suggesting that these cells are either poor generators or that they lack lipoxygenase activity. Trout erythrocytes generated no detectable amounts of cyclo-oxygenase or lipoxygenase products. All the solid tissues generated PGE2, 12-HETE, 12-HEPE and LTC4. In addition to these, LTB4 and LTB5 were detected in oesophagus, stomach, pyloric caecae, anterior and posterior intestine, skin, brain, spleen, liver, ovary, heart and gill. Brain, ovary and spleen also generated LXA4 and LXA5. Eicosanoid generation by eye and muscle was limited to 12-HETE, 12-HEPE, PGE2 and LTC4. The immunomodulatory role of various eicosanoids was examined with respect to the non-specific and humoral immune responses of the rainbow trout. Stimulation of macrophages with zymosan of E.coli resulted in the rapid phagocytic uptake of these particles and the concomitant generation of significant amounts of LXA4, LXA5, LTB4, LTB5, 12-HETE and 12-HEPE. Similarly, yeast and latex beads were also avidly phagocytosed but proved to be ineffective stimuli for eicosanoid generation. Prostaglandin E2, PGE3 and 12-HETE caused a dose dependent enhancement in the phagocytic uptake of yeast by macrophages in vitro. The lipoxygenase products, LTB4, LXA4 and LXB4, and the peptides, substance P and bradykinin, were all ineffective at modulating the phagocytic uptake of yeast. Lipoxin A4 potentiated the release of acid phosphatase from trout macrophages in a dose-dependent manner, while LXB4, PGE2, 12-HETE and LTB4 were all ineffective in modulating enzyme release.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available