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

Influence of interleukin-1alpha and COX-2 over the metabolism of arachidonic acid and glucose in isolated uterus of restricted diet rats

Isolated uteri from rats fed with a normal diet convert [14C]arachidonate into eicosanoids: PGE(2), PGF(2alpha), TXB(2) and 6-keto-F(1alpha). Restricted diet (50% of the normal diet, during 25 days) diminishes the levels of PGE(2), PGF(2alpha) and TXB(2). The addition of Interleukin-1alpha to the Krebs-Ringer bicarbonate medium increases sharply the production of eicosanoids. Inhibitors of nitric oxide synthase, Nomega-nitro-L-arginine methyl ester or aminoguanidine, do not prevent eicosanoids increase. Conversely, NS-398 (a selective inhibitor of COX-2) blocks the increase of eicosanoids while PGE(2) blocks eicosanoids production mediated by IL-1alpha. Other experiments with uteri of underfed rats confirm that interleukin-1alpha produces an increase in the glucose metabolism. The addition of Nomega-nitro-L-arginine methyl ester, aminoguadinine or NS-398 blocked such stimulation. It is concluded that Interleukin-1alpha produces an increase of glucose metabolism in uteri isolated from underfed rats by two different mechanisms, both involving COX-2: (1) nitric oxide independent and (2) nitric oxide dependent.

Effects of inhibitors of nitric oxide synthase on isolated uteri of fasting rats

The effects of inhibitors of nitric oxide synthase on the glucose metabolism of uteri isolated from 4-day underfed rats were studied. In control rats receiving normal feeding, the addition of indomethacin (5 x 10(-6) M); acetyl salicylic acid (10(-4) M); 400 microM of N(G)methyl-L-arginine, (L-NMMA) or 400 microM of sodium nitroprusside (SNP), does not modify the production of 14CO2 from U14C-glucose. On the contrary, in fasted rat uteri, indomethacin increases glucose oxidation significantly, while acetyl salicylic acid does not alter it. Also, the addition of L-NMMA has no effect. In another group of experiments, in the preparations containing indomethacin of uteri isolated from underfed rats, the addition of L-NMMA significantly changes the effect of indomethacin. Another inhibitor of nitric oxide synthase, N(omega)nitro-L-arginine methyl ester (L-NAME), or hemoglobin (2 microg ml(-1)) a nitric oxide scavenger have the same effects while N(omega)nitro arginine-D-methyl ester (D-NAME) does not. However (SNP), a nitric oxide donor, does not alter the production of 14CO2 in uteri isolated from fasted rats. These results show that in underfed rats, indomethacin increases glucose oxidation independently from its inhibiting effect on cyclooxygenase. Specific inhibitors of nitric oxide synthase can reverse this effect.

Effects of 17 beta estradiol on the metabolism of labelled arachidonic acid in uteri isolated from intact and ovariectomized rats. Influence of a restricted diet

The effects of restricted diet (50% of the normal intake during 25 days) on the metabolism of 14U arachidonic acid, were explored in uterine horn strips isolated from intact and ovariectomized rats, treated by 17 beta-estradiol or controls. The metabolism of arachidonic acid into different eicosanoids, PGE2, PGF2alpha, 6-keto PGF1alpha and TXB2, showed that the restricted diet diminished PGE2 and PGF2alpha, in intact rats, significantly. In contrast, this kind of feeding did not produce any change in castrated rats. Tissue preparations from previously estrogenized intact and castrated normal-fed rats showed that the production of different metabolites decreased. A similar result was obtained in intact rats subjected to a restricted diet. Nevertheless, in castrated underfed rats, estrogens did not produce any effect on the various eicosanoids analysed. These results showed that in isolated uteri, the effects of 17 beta-estradiol, on metabolite production from labelled arachidonic acid, are different from controls in ovariectomized diet-restricted rats.

Effect of fasting on the contractile activity and metabolism of labelled glucose and arachidonic acid in uteri isolated from intact and ovariectomized rat

The effects of fasting for 4 days on the isometric developed tension (IDT) and on the metabolism of labelled glucose and arachidonic acid in uteri from intact and spayed (25 days) rats, were explored. Starvation produces a fall in the contractile activity of intact rats, while in ovariectomized ones, no differences can be seen with respect to their controls. Fasting produces a fall in the glucose metabolism of both intact and ovariectomized rats, being more noticeable in the former group. Indomethacin (5 x 10(-6) M) increases the metabolism of labelled glucose in all experimental groups, significantly. The metabolism of exogenous arachidonic acid into different eicosanoids, PGE2, PGF2 alpha, 6-keto-F1 alpha and TXB2, shows that total food deprivation diminishes significantly the production of PGE2 in intact rats. In contrast, in ovariectomized starved rats, PGE2 increases markedly. The rest of the metabolites studied are not influenced by fasting. These results show that the effects of fasting on the contractile activity and on the release of some metabolites from arachidonic acid by the uteri isolated from intact rats are not seen in ovariectomized animals.

Influence of underfeeding on the spontaneous contraction and on metabolism of labelled arachidonic acid in uteri isolated from intact and ovariectomized rats

The effects of restricted diet (50% of the normal intake during 25 days) on the isometric developed tension (IDT), and on the metabolism of labelled arachidonic acid in uteri from intact and spayed (25 days) rats, were studied. Underfeeding produced a fall in the contractile activity of intact rats, while in ovariectomized rats contractile activity increased. Indomethacin reduced uterine contractile activity in all the cases under study. The metabolism of arachidonic acid into different eicosanoids, PGE2, PGF2 alpha, 6-keto-F1 alpha, and TXB2, showed that the restricted diet diminished PGE2 and PGF2 alpha levels in intact rats significantly. The reduction in uterine contractile activity and reduced levels of the arachidonic acid metabolites, PGE2 and PGF2 alpha, were not seen in ovariectomized animals.

Effects of ovarian steroids on glucose metabolism in uterus horns isolated from underfed rats. Influence of castration

The effect of a restricted diet (50% of the normal intake) during 25 days, on the glucose metabolism was explored in uterus horn strips isolated from intact and ovariectomized rats. In intact underfed rats, the formation of 14CO2 from U14C-glucose was significantly lower than in their controls. In castrated rats, the formation of 14CO2 increased after underfeeding. The return to ad libitum feeding increased glucose metabolism in both groups. Total food deprivation for 4 days diminished 14CO2 formation both in non-ovariectomized rats and in ovariectomized ones as measured at the end of this fasting period. This diminution was greater in intact rats. The increase of glucose metabolism provoked by the administration of s.c. estradiol, progesterone or their combination was more important in underfed intact animals. In intact rats, blood levels of endogenous estradiol and progesterone decreased as a result of underfeeding. In spayed ones, their low concentration increased in relation to their controls.

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)

Effects of a restricted diet on in vitro spontaneous activity and glucose metabolism in isolated rat uterus. Influence of castration

The effects of a restricted-diet (50% of the normal intake during 25 d) on the isometric developed tension (IDT), the metabolism of labelled glucose, and the levels of glycogen, of uteri isolated from ovariectomized (25 d) and non-ovariectomized rats were explored. The restriction of food intake produced a fall in the contractile activity of normal, non-ovariectomized, rats in permanent diestrous compared to normally fed rats in diestrous. On the contrary, in castrated rats, the IDT of isolated uterus from underfed rats, was significantly higher than its normal-fed controls. In normal rats the formation of 14CO2 from U 14C-glucose was significantly lower in uterine preparations from restricted-diet animals than the control one. On the other hand, in castrated rats, the formation of 14CO2 increased as a result of underfeeding. The post-incubation levels of glycogen in uteri from normal-fed animals diminished significantly in comparison to 0 time values. In uteri from rats subjected to a dietary restriction, the initial glycogen values were lower than in normal-fed controls, but they did not decline further after incubation in KRB medium. On the contrary, even when the levels of glycogen were significantly lower at 0 time than in diestrous animals, they diminished in ovariectomized rats after incubation, no matter the diet. The above results indicate that the effects of restricted-diet on contractile activity, levels of glycogen and glucose metabolism were not observed in ovariectomized rats. Further researches are needed to clarify that point.