5-Hydroxyeicosatetraenoic Acid Increases Prolactin Release from Rat Anterior Pituitary Cells*

The enzymatic breakdown of phospholipids to form arachidonic acid and its subsequent conversion to metabolites produced via the lipoxygenase pathway in anterior pituitary cells may contribute to the process of PRL release. The incubation of primary cultures of pituitary cells from female rats with the lipoxygenase product 5-hydroxyeicosatetraenoic acid (5-HETE; 5–100 μm) significantly increased PRL release in a concentration-dependent manner. The release of PRL induced by 45 μm 5-HETE was completely blocked by 1 μm dopamine. Penfluridol, an agent that binds to and inactivates several Ca+2- binding proteins, including calmodulin, decreased (P < 0.01) basal and 5-HETE-stimulated PRL release. Similarly, 50 μm D-600, a Ca+2 channel antagonist, significantly (P < 0.01) reduced basal and 5-HETE-induced PRL release. BW755c or RHC 80267, both of which reduce the production of arachidonic acid metabolites, including 5-HETE, significantly reduced basal PRL release. The inhibitory effects of BW755c and RHC 80267 on ...