ESTRADIOL-INDUCED CHANGES IN THE COMPOSITION OF PHOSPHOLIPID CLASSES OF QUAIL OVIDUCT - SPECIFIC REPLACEMENT OF ARACHIDONIC-ACID BY DOCOSAHEXAENOIC ACID IN ALKENYLACYL-GLYCEROPHOSPHOETHANOLAMINE

The phospholipid composition and the molecular species of the major su bclasses of ethanolamine and choline glycerophospholipids were determi ned during the natural or oestradiol-induced development of the quail oviduct. The phospholipid concentration increased significantly during oviduct development, and the proportion of ethanolamine glycerophosph olipids (EPL) remained constant while that of choline glycerophospholi pids increased. The immature oviduct contained the majority of its end ogenous arachidonic acid mass (71%) in EPL, mainly in alkenylacyl-glyc erophosphoethanolamine (alkenylacyl-GPE) (49% of the total). Oestrogen treatment induced the depletion of 20:4,n-6 specifically from this po ol, which indicates the biological importance of 20:4,n-6 molecular sp ecies in alkenylacyl-GPE as substrates for the oviduct phospholipases activated by oestradiol, and suggests that this EPL subclass is involv ed in the oestrogen-induced cell proliferation. Another striking resul t was the marked increase in 22:6,n-3 EPL molecular species following the oestradiol treatment and more particularly the strict substitution of 20:4,n-6 by 22:6,n-3 in alkenylacyl-GPE. We speculate that alkenyl acyl-GPE molecular species containing 22:6,n-3 may participate in the arrest of oestrogen-induced proliferation.