Exogenous action of 5-lipoxygenase by its metabolites on luteinizing hormone release in rat pituitary cells.
The stimulatory effect of exogenously administered potato 5-lipoxygenase (0.1-0.3 U/2 ml) on luteinizing hormone (LH) release was demonstrated in rat anterior pituitary cells in a superfusion system. Nordihydroguaiaretic acid (NDGA), an inhibitor of 5-lipoxygenase, abolished the effect of the enzyme on LH secretion. The secretory effect on LH after 5-lipoxygenase administration was biphasic and dependent on Ca2+ indicating that 5-lipoxygenase affects LH release through its oxygenation reaction. Another series of experiments demonstrated that activation of 5-lipoxygenase, expressed as production of leukotriene (LT) B4 and C4 (728 +/- 127 pg/10(6) cells and 178 +/- 23 pg/10(6) cells, respectively) occurs in rat pituitary cells after addition of Ca2+ ionophore A23187. However, LTB4 and LTC4 were not formed by pituitary cells that had previously been desensitized by gonadotropin-releasing hormone (GnRH), the physiological ligand of LH release. These results are consistent with a role of 5-lipoxygenase metabolites in the mechanism of GnRH-induced LH secretion.
Przylipiak
A
A
Department of Gynecology and Obstetrics, University of Heidelberg, F.R.G.
Kiesel
L
L
Habenicht
A J
AJ
Przylipiak
M
M
Runnebaum
B
B
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism* / Q000494:pharmacology; D001091:Arachidonate Lipoxygenases / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002396:Catechols / Q000494:pharmacology*; D002478:Cells, Cultured; D005260:Female; D007975:Leukotriene B4 / Q000096:biosynthesis; D016859:Lipoxygenase Inhibitors; D007986:Luteinizing Hormone / Q000378:metabolism*; D009637:Masoprocol / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013189:SRS-A / Q000096:biosynthesis
D002396:Catechols; D016859:Lipoxygenase Inhibitors; D010906:Pituitary Hormone-Releasing Hormones; D013189:SRS-A; D007975:Leukotriene B4; D000001:Calcimycin; D009637:Masoprocol; D007986:Luteinizing Hormone; D001091:Arachidonate Lipoxygenases; D001094:Arachidonate 5-Lipoxygenase; D002118:Calcium