This paper is only available as a PDF. To read, Please Download here.
Abstract
The possible existence of a selective and independent mechanism subserving the formation
of prostaglandin E1 (PGE1) and of prostaglandin E2 (PGE2) has been reported in previous studies from our group. In the present experiments
we have demonstrated that neutral lipid lipases play an important role yielding dihomo-gamma-linolenic
acid for the formation of PGE1. Indeed, exogenous triglyceride lipase added to the incubation bathing solution at
a concentration of 150 U/ml increased several fold the production of PGE1 by isolated uterine strips obtained from spayed rats. Nevertheless the presence of
the enzyme did not modify significantly the synthesis and release of bisenoic PGs
(PGE2 and PGF2α). When triarachidonin was added, as an artificial substrate into the incubating medium
in order to detect the presence of endogenous triacylglycerol lipase, we observed
a significant increment in the generation of PGE2 (p < 0.005) and of PGF2α (p < 0.001) without evident changes in the basal release of PGE1. On the other hand, the addition of phospholipase A2 (PLA2) at 0.2 U/ml, increased significantly the production of PGE2 (p < 0.001) but failed to alter the concentration of PGE1 in the incubating solution. Surprisingly, PLA2 did not enhance the synthesis of PGF2α in the present experiments, a situation for which we do not have a clear explanation.
Exogenous bradykinin (10−6 M), a well known stimulant of PLA2 activity in several tissues, also increased significantly (p < 0.001) the production
of PGE2 without altering that of PGE1. Results presented herein provide strong support to the notion that different enzyme
mechanisms and different lipid stores are linked to the formation of PGE1 and PGE2 in isolated rat uteri.
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Prostaglandins, Leukotrienes and Essential Fatty AcidsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Distribution of arachidonic acid and other fatty acids in the lipids of guinea pig uterus and plasma in relation to uterine prostaglandin synthesis.J. Reprod. Fert. 1961; 61: 325-333
- Fatty acids in plasma and red cell membranes in normal humans.Lipids. 1983; 18: 906-908
- Effects of essential fatty acids on prostaglandin biosynthesis.Biomed. Biochim. Acta. 1984; 43: 5114-5120
- The regulation of prostaglandin biosynthesis negative feedback mechanisms and the selective control of formation and immunity.Medical Hypothesis. 1980; 6: 687-709
- Is there a prostaglandin involvement in the positive inotropic action of histamine in isolated pregnant rat uterus, apparently mediated via H1?.Prost. Leuk. Med. 1987; 28: 285-302
- Effects of experimental diabetes on spontaneous contractions on the output of prostaglandins on the metabolism of labelled arachidonic acid in uteri isolated from ovariectomized rats. Influences of estradiol.Prostaglandins. 1988; 35: 191-205
- Norepinephrine altersProst. Leuk. Med. 1986; 22: 201-210
![Math Eq]()
output ratio in isolated uterus from ovariectomized rats. - How is the level of free arachidonic acid controlled in mammalian cells?.Biochem. J. 1982; 204: 3-16
- Pharmacologic influences on human ovarian contractions.Obstet. Gynec., N.Y. 1976; 47: 218-223
- Simplified thin layer chromatography of prostaglandins in biological extracts.Br. J. Pharmac. 1970; 40: 583
- The use of isolated organs for detection of active substances in the circulation blood.Br. J. Pharmac. Chemother. 1964; 23: 361-365
- Prostaglandins release by the spleen.Nature (Lond.). 1968; 218: 1135-1140
- Role of Phospholipase A2 in prostaglandin formation.Adv. Prost. & Tromb. Research. 1978; 3: 89-93
- The importance of phospholipase A2 in prostaglandin biosynthesis.Biochem. Pharmacol. 1976; 25: 285-294
- Time-Synchronized activation of lipolysis and fatty acids reacylation by bradykinin and angiotensin II in the perfused rabbit kidney.Adv. Prost. and Thromn. Research. 1980; 6: 255-258
- Hormone selective lipase activation in the isolated rabbit heart.Prostaglandins. 1977; 13: 1073-1091
- Release of prostaglandin E-like substance from canine kidney by bradykinin.Cir. Res. 1972; 31: 36-90
- Effects of hydrocortisone, oestradiol and progesterone n A-23187 stimulated prostaglandin output from the guinea-pig uterus superfused in vitro.Prostaglandins. 1985; 30: 575-583
- Factors subserving the enhancing effect of progesterone on the output of prostaglandin F2 in uteri from ovariectomized rats.Prost. Leuk. & Essential Fatty Acids. 1989; 35: 113-118
- Oxytocin enhances the basal release of uterine prostaglandin F2α, but not that of prostaglandin E1 or prostaglandin E2 and changes the metabolism of exogenous arachidonate favoring the formation of prostaglandin F2 alpha and 5-HETE relationships with its uterotonic action and modulation by estradiol.Prost. Leuk. & Essential Fatty Acids. 1990; 40: 203-209
- Metabolic factors regulating the generation of prostaglandins E1 and E2 by isolated rat uterus.Prost. Leuk. and Med. 1983; 11: 151-159
- Is there a prostaglandin involvement in the positive inotropic action of histamine in isolated pregnant rat uterus, apparently mediated via H1?.Prost. Leuk. Med. 1987; 28: 285-302
- On possible different mechanisms subserving the release of arachidonic and di-homo-gamma-linolenic acid for the formation of monoenoic and bisenoic prostaglandins in uteri from ovariectomized rats.Prost. Leuk. & Essential Fatty Acids. 1989; 38: 163-168
- Uptake and incorporation of arachidonic acid and of dihomogamma linolenic acid into tissue lipids in uterine strips isolated from ovariectomized-diabetic rats. Effects of 17-beta estradiol.Prost. Leuk. & Essential Fatty Acids. 1990; 41: 207-213
output ratio in isolated uterus from ovariectomized rats.Article info
Publication history
Accepted:
July 4,
1991
Received:
January 31,
1991
Identification
Copyright
© 1991 Published by Elsevier Inc.
