Dominance of type 1 angiotensin II receptor in the nonpregnant and pregnant bovine uterus

The present study was undertaken to characterize, determine and localize angiotensin II receptors in the nonpregnant and pregnant bovine uterus. In addition, the concentration of active renin, which is responsible for the generation of angiotensin, was determined. Autoradiography and angiotensin II receptor binding studies showed that all compartments of the bovine uterus contained high concentrations of angiotensin II receptors. In general, the type 1 angiotensin II receptor (AT1) predominated over the AT2 receptor. In the endometrium, the highest density was found in the caruncles and the AT1 receptor was always predominant. The density of angiotensin II receptors in the endometrium increased at the beginning of pregnancy, but decreased and reached values similar to those in nonpregnant animals near term. In the myometrium, the density of angiotensin II receptors was highest at or near the endometrial-myometrial junction. In this area, the predominant type of angiotensin II receptor in the uterus of cyclic cows varied, whereas the AT1 receptor always predominated during pregnancy. Non-AT1 and non-AT2 binding sites were found in the same locations as the angiotensin II receptors, but at lower densities. With the exception of the pregnant endometrium, all compartments contained higher active renin concentrations than found in plasma, indicating local synthesis of renin. This study demonstrates a difference in the expression of types of angiotensin II receptor in the bovine uterus compared with other species. The high densities of angiotensin II receptors localized in several important areas imply that the renin-angiotensin system participates in regulation of growth and tissue function in the bovine uterus.     

Element variations in pregnant and nonpregnant female rats orally intoxicated by aluminum lactate

Pregnant or nonpregnant female rats were orally intoxicated by aluminum lactate (400 mg Al/kg/d) from d 0–19 of gestation to determine the treatment's influence on element variations in the females and their fetuses. The aluminum levels of plasma, liver, spleen, and kidneys were significantly higher in treated pregnant rats than non-pregnant female rats. Differences of P, Ca, Cu, Zn, or Mg levels were observed among the four groups of female rats in the tissues and plasma. The aluminum content of the 20-d-old fetuses did not significantly differ between the treated and control groups. On the contrary, calcium and magnesium levels in the whole fetuses from treated or nontreated dams are significantly different.     

Differential expression of uterine NO in pregnant and nonpregnant rats with intrauterine bacterial infection

Previous studies have demonstrated that nitric oxide (NO) is involved in the uterine host defense against bacterial infection. In nonpregnant rats, NO production in the uterus was shown to be lower, and inducible NO synthase (NOS) expression was undetectable. However, studies in pregnant rats show abundant expression of inducible NOS with significant elevation in NO production in the uterus. We have recently reported that intrauterine Escherichia coli infection caused a localized increase in uterine NO production and inducible NOS expression in the nonpregnant rat. In our present study, we examined whether the uterine NO production, NOS expression, and uterine tumor necrosis factor-alpha protein are increased in pregnant rats with intrauterine pathogenic Escherichia coli infection. Unlike the nonpregnant state, the NO production in the infected uterine horn of pregnant rats was not significantly elevated after bacterial inoculation compared with the contralateral uterine horn. The expression of uterine NOS (types II and III) also did not show significant upregulation in the infected horn. This is in contrast to that in nonpregnant animals, in which type II NOS was induced in the uterus on infection. Moreover, intrauterine infection induced an elevated expression of tumor necrosis factor-alpha protein in the infected horn both of nonpregnant and of pregnant rats. These data suggest that the sequential stimulation of NOS expression, especially the inducible isoform, and generation of uterine NO are lacking during pregnancy despite an elevated tumor necrosis factor-alpha after infection. In summary, NO synthesis response may be maximal at pregnancy, and infection may not further induce the NO system. Present studies, together with our previous report that intrauterine infection-induced lethality in pregnancy rats was amplified with the inhibition of NO, suggest that pregnancy is a state predisposed for increased complications associated with intrauterine infection and that the constitutively elevated uterine NO during pregnancy may help contain or even reduce the risk of infection-related complications.     

Vascular function in alcohol-treated pregnant and nonpregnant mice

The effect of alcohol on maternal vascular adaptations to pregnancy is unknown. This study was designed to determine the effect of alcohol consumption on nitric oxide-mediated vascular function in mice during pregnancy. Female pregnant or nonpregnant C57BL/6J mice were fed a control diet or a liquid diet of 25% ethanol-derived calories for 13 days (from gestational days 6-18). Phenylephrine vasoconstriction was blunted in pregnancy compared with the nonpregnant state due to enhanced nitric oxide modulation, which was impaired by ethanol exposure. Although the EC50 and maximal responses to methacholine were not different in nonpregnant vs. pregnant mice, the nitric oxide component to methacholine-induced vasorelaxation was greater in the pregnant mice. Interestingly, alcohol affected only the pregnant animals in their response to methacholine. These data indicate that alcohol reduced the nitric oxide modulation of vascular response, which was more pronounced during pregnancy. These studies provide novel information regarding the effects of alcohol on the maternal vascular system during pregnancy and thereby contribute to further understanding of the adverse effects associated with prenatal alcohol exposure.     

Effect of ozone exposure on contractile activity and chemoreactivity of uterus horns longitudinal muscles of nonpregnant rats

With the purpose of studying the mechanism of ozone action on uterus smooth muscles it was investigated the influence of ozone-content (approximately 0.50 mkg/ml) Krebs' solution or its 10- and 100-fold dissolution on contractile activity and beta-adrenoreactivity of 56 longitudinal strips of uterus horns of 17 nonpregnant rats. Ozone at concentration approximately 0.50 mkg/ml (but not in concentration of approximately 0.05 and approximately 0.005 mkg/ml) reversibly raised frequency, amplitude and total contractile activity of intact myometrium strips, and also fast and reversibly reducel its beta-adrenoreactivity, i.e. decreased of inhibitory action of adrenaline (10(-8), 10(-7), 10(-6) g/ml), but did not change uterostimulatory effect of acetylcholine (10(-6) g/ml) and oxiyocin (5 x 10(-4) ME/ml), what evident about specificity of ozone beta-adrenoblokate effect. Ozone (approximately 0.50 and 0.05 mkg/ml) did not change ov value of potassium contracture of myometrium strips which was depolarized by hyperpotassium (60 mM KCL) Krebs' solution, but reduced inhibitory action of adrenaline (10(-8) g/ml). The question is being discussed about mechanisms of ozone beta-adrenoblocade actions, about clinical role of this phenomenon, and the possibility of using beta-adrenoreceptor sensibilizators direct action (histidine, tryptophan, tyrosine, trimetazidin and mildronat) at ozonotherapy with the purpose reduction of its negative effects.     

Oxidative damage in pregnant diabetic rats and their embryos

Free radical mechanisms may be involved in the teratogenesis of diabetes. The contribution of oxidative stress in diabetic complications was investigated from the standpoint of oxidative damage to DNA, lipids, and proteins in the livers and embryos of pregnant diabetic rats. Diabetes was induced prior to pregnancy by the administration of streptozotocin (45 mg/kg). Two groups of diabetic rats were studied, one without any supplementation (D) and another treated during pregnancy with vitamin E (150 mg/d by gavage) (D + E). A control group was also included (C). The percentage of malformations in D rats were 44%, higher than the values observed in C (7%) and D + E (12%) animals. D Group rats showed a higher concentration of thiobarbituric acid reactive substances in the mother's liver, however, treatment with vitamin E decreased this by 58%. The levels of protein carbonyls in the liver of C, D, and D + E groups were similar. The "total levels" of the DNA adducts measured, both in liver and embryos C groups were similar to the D groups. Treatment of D groups with vitamin E reduced the levels by 17% in the liver and by 25% in the embryos. In terms of the "total levels" of DNA adducts, the embryos in diabetic pregnancy appear to be under less oxidative stress when compared with the livers of their mothers. Graziewicz et al. (Free Radical Biology & Medicine, 28:75-83, 1999) suggested "that Fapyadenine is a toxic lesion that moderately arrests DNA synthesis depending on the neighboring nucleotide sequence and interactions with the active site of DNA polymerase." Thus the increased levels of Fapyadenine in the diabetic livers and embryos may similarly arrest DNA polymerase, and in the case of this occurring in the embryos, contribute to the congenital malformations. It is now critical to probe the molecular mechanisms of the oxidative stress-associated development of diabetic congenital malformations.     

Interaction of vasopressin and prostaglandins in the nonpregnant human uterus

The interaction of vasopressin (VP) and prostaglandins (PG) on the nonpregnant human uterus was studied and . In organ baths arginine (A)- and lysine (L)-VP in concentrations of 0.6 to 100 ng/ml stimulated small human myometrial strips and uterine artery preparations to a similar degree. When these VPs were given in the presence of indomethacin or naproxen in concentrations of 1 μg/ml and 5 μg/ml, respectively, the myometrial and arterial responses were not significantly influenced. PGF_2α in concentrations of 0.01–100 ng/ml stimulated the myometrial preparations but caused a slight relaxation of the arteries, with PGE₂ the myometrial effects were insignificant and the relaxation of the arteries greater. When AVP was given together with either of the PGs to the bath the result was generally a summation of the individual effects of both types of substances. - In vivo during intrauterine pressure recordings in nonpregnant women 1–2 days before onset of menstruation LVP in single intravenous injection of 1.2 μg markedly stimulated uterine contractions. The response remained practically unaltered after pretreatment with 500 μg of naproxen given orally. The responses to LVP were also closely similar before, during and after intravenous infusion of PGF_2α at a rate of 5 μg/min. - It is concluded that the effect of VP on myometrium and uterine arteries is not to any great extent mediated by local synthesis of PG and that PGs do not cause potentiation or inhibition of the VP effects on the nonpregnant uterus.     

Mercury 203 distribution in pregnant and nonpregnant rats following systemic infusions with thiol-containing amino acids

Near-term pregnant (gestational day 17) and nonpregnant Long-Evans female rats were continuously infused into the external jugular vein with 0.1 mmole/hour L-cysteine, 0.1 mmole/hour L-leucine, or saline. At 24, 48, and 72 hours, 50 mumole/hour [203Hg]-MeHgCl was administered over 1 hour. Total 203Hg body burden, brain, kidney, liver, and blood 203Hg concentrations were determined at 96 hours by gamma scintillation spectrometry. Despite significantly greater 203Hg whole body retention in the pregnant animals 203Hg concentrations in blood, brain, kidney, and liver were higher in nonpregnant rats. In addition, brain 203Hg concentrations in both pregnant and virgin rats were significantly higher in L-cysteine-treated rats compared with controls. These results suggest that the fetus may act as a "sink" for MeHg, thus decreasing 203Hg concentrations in maternal blood, brain, kidney, and liver. Furthermore, the data indicate that brain uptake of methylmercury in both pregnant and nonpregnant rats is enhanced by chronic L-cysteine infusion, lending support to the hypothesis that methylmercury in the rat may be translocated across the blood-brain barrier by the neutral amino acid carrier transport system.     

Interaction of vasopressin and prostaglandins in the nonpregnant human uterus

The interaction of vasopressin (VP) and prostaglandins (PG) on the nonpregnant human uterus was studied in vitro and in vivo. In organ baths arginine (A)- and lysine (L)-VP in concentrations of 0.6 to 100 ng/ml stimulated small human myometrial strips and uterine artery preparations to a similar degree. When these VPs were given in the presence of indomethacin or naproxen in concentrations of 1 microgram/ml and 5 micrograms/ml, respectively, the myometrial and arterial responses were not significantly influenced. PGF2 alpha in concentrations of 0.01-100 ng/ml stimulated the myometrial preparations but caused a slight relaxation of the arteries, with PGE2 the myometrial effects were insignificant and the relaxation of the arteries greater. When AVP was given together with either of the PGs to the bath the result was generally a summation of the individual effects of both types of substances.--In vivo during intrauterine pressure recordings in nonpregnant women 1-2 days before onset of menstruation LVP in single intravenous injection of 1.2 micrograms markedly stimulated uterine contractions. The response remained practically unaltered after pretreatment with 500 micrograms of naproxen given orally. The responses to LVP were also closely similar before, during and after intravenous infusion of PGF2 alpha at a rate of 5 micrograms/min.--It is concluded that the effect of VP on myometrium and uterine arteries is not to any great extent mediated by local synthesis of PG and that PGs do not cause potentiation or inhibition of the VP effects on the nonpregnant uterus.     

Embryotoxicity studies of norfloxacin in cynomolgus monkeys: I. Teratology studies and norfloxacin plasma concentration in pregnant and nonpregnant monkeys

Norfloxacin, a new orally active antibiotic, was investigated in cynomolgus monkeys for potential developmental toxicity. Fifty-seven monkeys were administered a control vehicle or norfloxacin by nasogastric gavage during the major period of organogenesis on gestational days (GD) 21 through 50 at doses of 0, 50, 100, 150, or 200/300 mg/kg/day. There was no evidence of teratogenicity at any dose level. Maternotoxicity and a significant increase in embryolethality occurred following doses of 200/300 mg/kg/day. The maternotoxicity was not expected based on range-finding studies in nonpregnant female monkeys, which showed no signs of toxicity in doses up to 500 mg/kg/day. Additional studies were conducted to determine if norfloxacin caused similar toxicity later in gestation. Forty-six pregnant monkeys were dosed with a control vehicle or 200 mg/kg/day norfloxacin for one of three 10-day periods on GD 36-45, 71-80, or 111-120. There were no maternotoxic, embryotoxic, or fetotoxic effects observed. Plasma concentrations of norfloxacin in five cynomolgus monkeys following 50 and 200 mg/kg oral doses were not dose-proportionate. However, at a given dose, administered in cross-over fashion, plasma concentrations of norfloxacin were higher in nonpregnant females (approximately 20-40%) than during pregnancy when the same subject was compared. At the no-observed-effect dose for maternal and embryotoxicity (50 mg/kg), peak plasma concentrations of norfloxacin in pregnant cynomolgus monkeys are approximately threefold higher than those observed in human volunteers receiving norfloxacin at the maximum recommended therapeutic dose of 400 mg (5.7 mg/kg based on 70 kg body weight) twice per day.     

Plasma vitamin D metabolite levels in pregnant and nonpregnant ewes

1. Maternal calcium homeostasis during pregnancy is strained due to fetal mineral requirements for bone formation. 2. In most species, the mother adjusts to the mineral requirements of the fetus with alterations in her metabolism of vitamin D that include a decrease in plasma 25-(OH)D levels and an increase in circulating levels of the hormone, 1,25-(OH)2D. 3. Plasma 25-(OH)D and 1,25-(OH)2D levels in adult male, adult female and pregnant sheep were measured by specific radioreceptor binding assays. 4. Pregnancy did not alter circulating levels of 25-(OH)D or 1,25-(OH)2D in the sheep. 5. The pregnant ewe differs from all species studied to date in that maternal plasma 1,25-(OH)2D levels do not rise as a result of pregnancy.     

Uterine arterial responses to arachidonate in pregnant and nonpregnant rabbits

Several investigators have suggested that prostaglandins (PG) may play a major regulatory role in maintaining uteroplacental blood flow in pregnancy. The present study was undertaken to assess the response of the uterine artery from near-term pregnant and nonpregnant rabbits to the PG precursor Na-arachidonate (AA) (C 20:4). Isolated uterine arterial strips were equilibrated isometrically under their optimal resting tensions in physiologic salt solution. Uterine arteries from pregnant rabbits elicited significantly greater contractile responses to arachidonate over the dose-range studied (10(-10)-10(-3) M) than did arteries from nonpregnant rabbits. These contractions were seen whether the strip was relaxed or precontracted with potassium chloride (30 mM). The contractile responses to AA were antagonized in a competitive manner by pretreating the arteries with the cyclooxygenase inhibitors meclofenamate (10(-5) M) or indomethacin (10(-5) M), thus suggesting that the contractile response to AA was the result of its conversion to prostanoids by the cyclooxygenase pathway. The possibility that the AA response was a general fatty acid effect was ruled out since oleate (C 18:1) had no effect on the arteries. In addition, prostaglandins F2 alpha and E2 (10(-5) M) also contracted the uterine arteries from the pregnant group. It is concluded from these studies that the uterine arterial wall from near-term pregnant rabbits utilizes the PG precursor, AA, for the production of prostanoids which, in turn, cause uterine arterial constriction.     

Hemodynamic response to anesthesia in pregnant and nonpregnant ICR mice

Mean arterial blood pressure (BP) and heart rate (HR) during and after recovery from anesthesia in pregnant and nonpregnant ICR mice were evaluated. Mice were evaluated during mechanical ventilation, from 15 to 60 min after induction of anesthesia. The anesthetic protocols were pentobarbital (80 mg/kg, given intraperitoneally [i.p.]); two low doses of ketamine and xylazine (90 mg/kg, 7.5 mg/kg, respectively, i.p., with a second dose given 20 min after the initial dose); and a single high dose of ketamine and xylazine (150 mg/kg, 12.5 mg/kg, respectively, i.p.). The BP was measured in the right carotid artery, using a fluid-filled catheter connected to a chamber containing a solid-state pressure transducer. Mechanical ventilation was performed via tracheotomy, using a normalized minute ventilation of 3.5 ml*min-1*g-1 for nonpregnant mice and 3.0 ml*min-1*g-1 for pregnant mice. Mean BP was lower and HR was higher in pregnant than in nonpregnant mice for each anesthetic protocol. Pentobarbital induced significantly greater tachycardia and hypotension than did the other protocols. The average BP and HR were similar between two low doses and a single high dose of ketamine and xylazine. During spontaneous breathing from 30 to 180 min after recovery from anesthesia by use of a single low dose, ketamine and xylazine induced similar HR profiles, but mean BP in pregnant mice recovered earlier than did that in nonpregnant mice. These results suggest that ketamine and xylazine induced adequate anesthesia for superficial surgical procedures in pregnant and nonpregnant mice while inducing small changes in HR and BP, and pregnancy resulted in a different hemodynamic reaction in response to ketamine and xylazine. These data will be useful for the design and interpretation of physiologic protocols using pregnant and nonpregnant genetically targeted mice.