The biosynthesis of the 3-series prostaglandins in rat uterus after alpha-linolenic acid feeding: mass spectroscopy of prostaglandins E and F produced by rat uteri in tissue culture.
The abnormal uterine activity associated with dietary n-3 fatty acids may result from competitive inhibition of PG2 production. Uterine synthesis of 2- and 3-series prostaglandins F(PGF) and E(PGE) was studied using mass spectrophotometry in rats fed diets containing predominantly n-3 fatty acid, n-6 fatty acid, or control pelleted diet. Mass spectra of PGF (Me, TMS and Me, TBDMS derivatives) synthesised by uteri of n-3 fed rats were characterised by 8 ions containing the n-3 double bond, and m.i.d. of the 651/653 ions of PGF-Me, TBDMS indicated PGF3 alpha synthesis (44 +/- 8% and 13 +/- 2% of PGF release by uteri incubated + or -5 micrograms/ul calcium ionophore A23187 respectively). In uteri from the control diet group incubated with ionophore, PGF3 alpha ions were detected and PGF 3 alpha represented 9.5 +/- 1.0% of PGF alpha release. Similarly, analysis of PGE from uteri of n-3 fed rats indicated that PGE3 (16 +/- 6% of PGE) was released in the presence of ionophore A23187. Synthesis of 3-series PG by rat uteri was detected after only 3 weeks of n-3 diet. The capacity to synthesise 3-series PG increased at intracellular calcium concentrations which mimicked cell calcium during decidual autolysis at parturition. These experiments suggest that uterine synthesis of 3-series PG is regulated by the specifity of enzymes incorporating fatty acids, rather than by the cyclooxygenase enzyme.
Leaver
H A
HA
Department of Pharmacology, University of Edinburgh, UK.
Howie
A
A
Wilson
N H
NH
D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D015237:Dinoprost / Q000096:biosynthesis; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D008042:Linolenic Acids / Q000494:pharmacology*; D009924:Organ Culture Techniques; D011458:Prostaglandins E / Q000096:biosynthesis* / Q000302:isolation & purification; D011460:Prostaglandins F / Q000096:biosynthesis* / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
D004041:Dietary Fats; D008042:Linolenic Acids; D011458:Prostaglandins E; D011460:Prostaglandins F; C034238:prostaglandin F3alpha; D015237:Dinoprost