Stimulation of gonadotropin release by arachidonic acid and its lipoxygenase metabolites in superfused pituitary cells.

Luteinizing hormone and follicle stimulating hormone secretion was stimulated by 4 min pulses of arachidonic acid (3 X 10(-5) to 10(-4)M) in superfused rat pituitary cells. The effect of its lipoxygenase metabolites, 5-hydroxy-6,8,11,14-eicosatetranoic acid (5-HETE) and 15-hydroxy-5,8,10,14-eicosatetranoic acid (15-HETE) was more potent on hormone release when added in the same dose. Using 3 X 10(-5)M 5-HETE, its releasing activity on gonadotropins was comparable to that of GnRH (10(-9)M). 15-HETE (3 X 10(-5)M) was even more potent on LH and FSH secretion than 5-HETE. The secretory profile induced by 5-HETE and 15-HETE was also similar to that shown for GnRH, resulting in a rapid increase and a more prolonged decline of the hormone release. The addition of these fatty acids to superfused pituitary cells did not alter the response of the cells to their physiological ligand. These findings give further support to the proposal that metabolites of arachidonic acid may be involved in receptor-mediated mechanisms of gonadotropin release in pituitary cells.