Polyunsaturated fatty acids can be oxygenated by cytochrome P450 to hydroxy and epoxy fatty acids. Two major classes of hydroxy fatty acids are formed by hydroxylation of the omega-side chain and by hydroxylation of bisallylic methylene carbons. Bisallylic cytochrome P450-hydroxylases transform linoleic acid to 11-hydroxylinoleic acid, arachidonic acid to 13-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid, 10-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and 7-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and eicosapentaenoic acid to 16-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid, 13-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid and 10-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid as major metabolites. The bisallylic hydroxy fatty acids are chemically unstable and decompose rapidly to cis-trans conjugated hydroxy fatty acids during acidic extractive isolation. Bisallylic hydroxylase activity appears to be augmented in microsomes induced by the synthetic glucocorticoid dexamethasone and by some other agents, but the P450 gene families of these hydroxylases have yet to be determined. The fatty acid epoxides, which are formed by cytochrome P450, are chemically stable, but are hydrolyzed to diols by soluble epoxide hydrolases. Epoxidation of polyunsaturated fatty acids is a prominent pathway of metabolism in the liver and the renal cortex and epoxy-genase activity appears to be under homeostatic control in the kidney. Many arachidonate epoxygenases have been identified belonging to the CYP2C gene subfamily. Epoxygenases have also been found in the central nervous system, endocrine organs, the heart and endothelial cells. Epoxides of arachidonic acid have been found to exert pharmacological effects on many cells.

The synthesis of prostaglandins (PGs) by several tissue components of brook trout (Salvelinus fontinalis) ovaries was investigated using radiolabeled precursor incorporation and radioimmunoassays for PGE and PGF. PGE2 and PGF2α were synthesized from 14C arachidonic acid (AA) by the follicle walls of mature oocytes. Synthesis was significantly greater in follicles taken postovulation as compared to those sampled prior to germinal vesicle breakdown. However, the most extensive synthesis of PGs occurred with tissue outside of the mature follicles (i.e., extrafollicular[EF]). When incubated with AA, the predominant primary PG produced by this tissue was PGE2. EF tissue could be separated microscopically into two major fractions—immature follicles and stromal tissue. When these tissue fractions were incubated separately with AA the stromal fraction retained the ability to produce PGE2, while the immature follicles increased synthesis of PGF2α. 14C‐Eicosatrienoic acid was converted to PGE1 and PGF1α by EF tissue but in significantly reduced quantities relative to AA. Fatty acid analysis indicated that there were significant quantities of arachidonic, eicosapentaenoic, and docosahexaenoic acids in both follicles and EF tissue, but there was not a significant difference between the two tissues in the absolute amount of arachidonate/mg tissue. In experiments using radioimmunoassays (RIAs), the highest quantities of PGE were measured in incubates containing EF tissue. This supported the results obtained through arachidonic acid incorporation and suggested that this tissue is the primary source of PGE in the brook trout ovary. In contrast, the mature follicules that were undergoing ovulation in vitro produced significant quantities of PGF, whereas the EF tissue production of PGF, measured by RIA, was very low. The results clearly indicate that there are several potential sites for PG synthesis within the trout ovary that differ in their capacity to produce E and F prostaglandins.

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