Prostaglandin E2 and prostaglandin F2 regulation of triglyceride levels in uterine smooth muscle from restricted-diet estrous and diestrous rats

Lipid metabolism in the embryos of diabetic rats during early organogenesis: modulatory effect of prostaglandin E2

The purpose of this work was to evaluate de novo lipid biosynthesis and the lipid profile, and to study the effect of prostaglandin E2 (PGE2; prostaglandin has previously been found to be involved in diabetes embryopathy) on lipid metabolism in embryos from control and streptozotocin-induced diabetic rats during organogenesis. Increased levels of triacylglycerols were found in embryos of diabetic rats compared with controls, whereas no differences were detected in the levels of cholesterol, cholesterylester, phosphatidylcholine and phosphatidylethanolamine. When the de novo synthesis of lipids in the embryo was studied using [14C]acetate as a tracer, a diminished rate of incorporation of [14C]acetate into the evaluated lipid classes was detected in the diabetic embryo compared with controls. Addition of PGE2 did not modify the incorporation of [14C]acetate into any of the lipid species of control embryos, but enhanced the incorporation of [14C]acetate into triacylglycerol, cholesterylesters, phosphatidylcholine and phosphatidylethanolamine of embryos from diabetic rats. The study's results show alterations in both synthesis and concentrations of lipids in the embryos of diabetic rats. Interestingly, the results demonstrate that the addition of PGE2, a prostaglandin that reverses the embryonic morphological abnormalities induced by diabetes, prevents disturbances in embryo lipid synthesis caused by diabetes.

Different effect of a restricted diet on isolated uteri of ovariectomized and non-ovariectomized rats. Influence of indomethacin and prostaglandins

The effect of restricted diet (50% of the normal intake during 25 days) on the metabolism of labelled glucose, in uteri isolated from ovariectomized (25 days) and non-ovariectomized rats, was explored. In intact rats subjected to dietary restriction, the formation of 14CO2 from U 14C-glucose is significantly lower than in controls. Indomethacin increases glucose metabolism, being even higher in underfed rats' uteri. This effect is not altered by the addition of prostaglandins E1, E2 or F2 alpha to the medium. In castrated rats, the formation of 14CO2 increases due to underfeeding and this result is not altered by indomethacin. Glycogen and triglyceride values in the isolated uterus were measured immediately after killing (O time) and after 60 min of incubation in a glucose-free KRB medium. The post-incubation levels of glycogen from intact normal fed animals diminished in comparison to initial values, and this result was not altered by the addition of indomethacin. In rats subjected to dietary restriction, glycogen did not decline further after incubation, and the addition of indomethacin led to a significant fall. In spayed rats, glycogen diminished after 60 min both in normal fed rats and in underfed ones, and they were not affected by the indomethacin. In intact underfed rats, uterine triglycerides fall after 60 min. Indomethacin changes this situation, which is again evoked by the addition of PGF2 alpha. In ovariectomized rats, uterine triglycerides are neither altered by a restricted diet nor affected by indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic underfeeding on uterine glycogen of rats. Influence of indomethacin and nordihydroguaiaretic acid

Glycogen values in uterine strips isolated from normal-fed estrous or diestrous rats, or from rats fed a restricted diet (50% of normal food intake for 25 days) were measured. Determinations were made immediately after killing (0 time or post-isolation) as well as after incubation in glucose-free medium (60 min time or post-incubation). The post-incubation levels of glycogen in the uteri from normal-fed animals diminished significantly in comparison to post-isolation values, and this decrement was not modified by the addition of indomethacin, nordihydroguaiaretic acid or exogenous prostaglandins E1, E2 or F2 alpha. In rats fed a restricted-diet, the initial glycogen values (0 time) were significantly lower than in normal-fed controls, but did not decline further after incubation in glucose-free medium (60 min time). The addition of indomethacin, acetylsalicylic acid or of nordihydroguaiaretic acid led to a significant fall in the glycogen levels, and exogenous PGE1, PGE2 or PGF2 alpha failed to alter the effects of the inhibitors. The values of PGE and PGF prostaglandins release to the medium by the uterus from restricted-diet rats did not differ from those obtained in the experiments with normal-fed animals. Administration of 17-beta estradiol to restricted-diet rats led to suppression of the effects of this diet on the glycogen concentration. The above results indicate that in rats subjected to a prolonged period of dietary restriction, the uterine glycogen becomes responsive to the effects of cyclooxygenase and lipoxygenase inhibitors, suggesting the operation of some regulatory mechanism during critical periods of nutrition.

Effect of partial starvation on in vitro spontaneous activity and glycogen levels of uterine smooth muscle from pregnant and non pregnant rats

Effects of a restricted-diet (50% of the normal feeding) given during 14 days, on the isometric developed tension (IDT) of uterine horns isolated from pregnant and non pregnant (diestrous) rats, incubated in a KRB-medium without glucose, were explored. In 14 days-pregnant rats, dietary restriction did not alter the contractile activity with respect to normal-fed controls. Besides, levels of uterine glycogen, immediately after killing the animals or after 60 min incubation, remained unaltered. In advanced pregnancy partial starvation led to decay of spontaneous contractile activity after 60 min incubation. However, the considerable increment in the levels of tissue glycogen at 0 time was not modified, nor its decrease at the end of the in vivo experimental period. In non-pregnant rats, a reduced feeding did not alter the development of contractile tension, but exerted a pronounced effect on the glycogen levels: these were significantly lower than controls at 0 time but suffered no changes after 60 min on in vitro activity. Indomethacin appeared to have no effect on the spontaneous contractile activity of 14 days-pregnant rats. It significantly depressed contractility in 21 days-pregnant rats. Indomethacin did not modify the levels of glycogen in any of the experimental groups.

Effect of dietary restriction on triglyceride levels in the uterus isolated from pregnant rats. Influences of prostaglandins and indomethacin

Triglyceride (TGs) concentrations in uterine strips isolated from 14 or from 21 days-pregnant rats, either normal-fed or following a restricted-diet rats (50% food intake for 14 days), were measured. Determinations were made immediately after killing (0 min time or post-isolation) as well as after a period of incubation in glucose-free medium (60 min time or post-incubation). The post-isolation levels of TGs (0 min) in the uterus from normal-fed animals at 14 or at 21 days of pregnancy, were significantly higher in implantation sites than in the interembryonic segments. These values of TGs (0 time) did not change, in comparison to post-incubation concentrations (60 min), either without additions or in the presence of indomethacin (5 X 10(-6) M) or of prostaglandins (PGs) E1, E2 or F2 alpha (10(-7) M). At 0 time, uterine TGs of rats subjected to dietary restriction, increased as pregnancy progressed, more than in normal-fed controls. The post-incubation (60 min) pattern was different depending on the days of pregnancy; i.e. at 14 days, incubation in Krebs-Ringer Bicarbonate-medium (KRB) led to a significant fall unaffected by the addition of propranolol (10(-6) M). However, in the presence of indomethacin, TGs values had a level similar to the initial one (0 time). Furthermore, exogenous PGE1 or PGE2 failed to alter the effect of indomethacin, as PGF2 alpha did.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin E2 alters the metabolism of labelled glucose in uteri isolated from ovariectomized rats. Effects of 17-beta estradiol and indomethacin

The effects of prostaglandins (PGs) E1, E2 and F2 alpha on the oxidation of labelled glucose in uterine strips from ovariectomized rats, were explored. Moreover, the influences of in vivo estrogenization of spayed rats and the presence in vitro of indomethacin (10(-6)M) on labelled glucose metabolism by isolated uteri, were also determined. PGE2 (10(-7)M), but not PGE1 or PGF2 alpha, enhanced significantly the formation of 14CO2 from U14C-glucose in uteri from spayed rats. After the injection of 17-beta estradiol to castrated animals prior to sacrifice the three PGs augmentated in vitro uterine glucose metabolism. In uterine strips from spayed non-estrogenized rats incubated with indomethacin, only PGE2 (10(-7) and 10(-6) M) incremented the formation of 14CO2 from labelled glucose, whereas PGE1 and PGF2 alpha were devoid of action, whereas in uteri from ovariectomized-estrogenized animals also incubated with indomethacin, PGE1, PGE2 and PGF2 alpha enhanced significantly the metabolism of labelled glucose, as was observed in the absence of indomethacin. However, in the presence of indomethacin the magnitude of the stimulation evoked by PGs in vitro was 3 to 4 times greater than without the inhibitor of the cyclo-oxygenase. The role of estradiol modulating the actions of PGE2 and PGF2 alpha on uterine glucose metabolism and possible reasons subserving the influence of indomethacin incrementing the effects of PGs on glucose oxidation in uteri from spayed-estrogenized rats, are discussed.

Triglycerides in isolated rat uterine strips. Influences of glucose deprivation, 2-deoxy-D-glucose, estrogens and exogenous or endogenous prostaglandins E1, E2 and F2 alpha

Triglyceride (TG) levels in uterine strips isolated from natural estrous, ovariectomized or ovariectomized, estradiol-injected rats, were explored. Determinations were performed either immediately after isolation (initial or 0 time) as well as after one hour period of incubation (60 min time) in glucose containing or in glucose-free solution. The influences of indomethacin alone (5 X 10(-6) M) or of indomethacin plus prostaglandins (PGs) E2, E1 or F2 alpha (10(-7) M). delivered in vitro at the beginning of the incubation, and of 2-deoxy-D-glucose (2-DG) at 11.0 mM, were also studied. Ovariectomized animals (25 days); estrous animals or spayed 17-beta estradiol-injected animals (0.5 microgram + 1.0 microgram, 24 hours prior to sacrifice), were employed. At 60 min time in glucose-free medium, but not in glucose containing solution, triglycerides declined significantly in strips from spayed rats, the diminution being prevented by in vitro indomethacin. The presence of exogenous PGF2 alpha or of PGE1, but not that of PGE2, abolished the preventive effect of indomethacin. Initial TG levels in spayed uteri treated with estradiol were significantly smaller that in untreated controls. However, under these conditions, indomethacin alone or indomethacin plus the tested PGs, had no action, the same being evident at natural estrus. In strips from spayed rats and incubated in the absence of glucose but with the presence of 2-DG, the effects of indomethacin and of indomethacin plus exogenous PGs on tissue TG levels were similar, although more evident, than in the sole absence of extracellular glucose. Moreover, TG levels in uterine strips obtained from ovariectomized rats injected with 17-beta estradiol and incubated for 60 min in glucose-free medium plus 2-DG, were smaller than immediately after isolation (0 time), the decrement being prevented by indomethacin, not affected by PGE2 and abolished by PGE1 or by PGF2 alpha. The foregoing results suggest that the diminution of TG in uterine strips incubated in the absence of glucose could be due to a greater metabolic utilization of neutral fats, a phenomenon possibly associated to the lack of exogenous substrate. Moreover, this decrement of tissue TG appears to be linked to the influence of certain PGs and of estrogens, for in ovariectomized, but not in estrous or in spayed-estrogenized conditions, indomethacin prevented the TG decrement in glucose-free solution, whereas PGs E1 and PGF2 alpha abolished the preventive action of indomethacin.(ABSTRACT TRUNCATED AT 400 WORDS)

Different effects of prostaglandins E2 and F2 alpha on triglyceride levels in uterine smooth muscle from diabetic diestrous rats

Triglyceride (TG) concentrations in uterine strips isolated from diestrous normal rats, from diestrous streptozotocin (single iv. injection of 65 mg X Kg body weight-1)-diabetic rats and from diestrous diabetic animals, treated in vivo with insulin (protamine zinc insulin 4U X day-1, 6 days, sc.), were measured. Determinations were made immediately following killing (0 min, or postisolation) as well as after an incubation period in glucose-free medium (60 min, or postincubation), with or without additions. The basal or postisolation levels of TGs (0 min) in the uterus from control normal rats (TGs: 17.0 +/- 0.5 mumol X g-1, d.w.; blood glucose: 100.4 +/- 4.8 mg X dl-1) were lower (P less than 0.001) than in streptozotocin-diabetics (TGs: 28.5 +/- 0.6 mumol X g-1, d.w.; blood glucose: 302.0 +/- 10.1 mg X dl-1) and the treatment with insulin (blood glucose: 165.0 +/- 14.7 mg X dl-1), restored TGs towards normal (19.3 +/- 1.3 mumol X g-1, d.w.). The postisolation levels of TGs (0 min) in the uterus from normal controls did not differ in comparison with postincubation values (60 min), either without additions or in presence of indomethacin (5 X 10(-6)M) or of prostaglandins (PGs) E2 or F2 alpha, at 10(-9)M. On the contrary, in uteri from diabetic animals, the higher initial TG levels diminished spontaneously in comparison to controls (P less than 0.001) following 60 min of incubation without additions; this decrement being antagonized by indomethacin or by propranolol (10(-6)M). Moreover, exogenous PGE2 failed to alter the effect of indomethacin, whereas PGF2 alpha evoked its abolition. In addition, propranolol, which effectively blocked the spontaneous decrement of TGs as did indomethacin, prevented also the influence of PGF2 alpha on the action of the cyclo-oxygenase inhibitor. In the case of uteri from diabetic rats treated in vivo with insulin, TG levels remained unaltered at the end of an incubating period of 60 min without additions and so they did following the administration of indomethacin or PGF2 alpha. The results document that the regulation of TGs in the diestrous rat uteri, suspended in glucose-free solution, is affected differently by PGE2 and F2 alpha, depending on the existence or not of an untreated diabetic condition. They also suggest that the action of PGF2 alpha may involve the activation of tissue beta-adrenoreceptors.