Liver Of Dams Research Articles

Comparison of DNA alkylation, fragmentation, and repair in maternal and fetal tissues of pregnant rats treated with a single dose of ethyl methanesulfonate, ethyl‐N‐nitrosourea, N‐nitrosodiethylamine, and methyl‐N‐nitrosourea

The occurrence and persistence of DNA damage, as detected by the alkaline elution technique, have been studied in some tissues of both fetal and adult Sprague-Dawley rats (18th day of gestation) after administration of a single equimolar dose (0.5 mmol/kg) of ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU), N-nitrosodiethylamine (NDEA), and N-methyl-N-nitrosourea (MNU). EMS, ENU, and MNU, injected intravenously, produced a statistically significant increase of DNA elution rate, which is considered indicative of DNA fragmentation, in both maternal and fetal liver, kidney, and brain. NDEA, introduced by gastric gavage, induced DNA breaks in both liver and kidney of dams, but only in the liver of fetuses. The frequency of DNA lesions was found to vary with the four alkylating agents and in the three organs tested, to exhibit a different time course, and usually to be higher in maternal than in fetal tissues. Results provided by the concomitant determination of DNA binding levels demonstrated a satisfactory correlation with the amounts of DNA fragmentation. In contrast, the values of both these parameters did not show any positive correlation with the different susceptibility of the three organs to tumor induction. In conclusion, these findings suggest that when a compound is not available in radiolabeled form, measurement of DNA fragmentation may represent a useful alternative to the determination of DNA binding level in order to obtain information on the distribution of its reactive species in maternal and fetal tissues.

The effect of diabetes on the molecular localization of maternal and fetal zinc and copper metalloprotein in the rat

The molecular localization of maternal and fetal zinc and copper metalloproteins in diabetic and control rats was studied. Compared to controls, liver and kidneys of diabetic dams showed an increased concentration of zinc and copper that was associated with metallothionein. In contrast, fetuses of diabetic dams had lower zinc and metallothionein levels than fetuses from controls. The abnormal maternal trace element metabolism seen with diabetes resulted in alterations of zinc uptake and/or retention of their fetuses.

Maternal Zinc Deprivation and Interleukin-1 Influence Metallothionein Gene Expression and Zinc Metabolism of Rats

The influence of maternal dietary zinc intake and recombinant human interleukin-1 alpha (rhIL-1 alpha) administration on metallothionein gene expression and the distribution of 65Zn were investigated. Pregnant rats were fed diets containing 1, 5, 30 or 180 mg Zn/kg diet in an equalized regime from d 13-20 of gestation. Metallothionein gene expression was examined by Northern blot and dot blot hybridization using combined 60-mer oligonucleotides specific for rat metallothionein-1 and -2 genes. Expression was progressively depressed in the fetal livers and livers and kidneys of dams fed diets marginal (5 mg/kg) and deficient (1 mg/kg) in zinc content. Administration of rhIL-1 alpha increased expression in maternal liver, placenta and in fetal liver of dams fed adequate or deficient diets. Kinetics of intravenously administered 65Zn showed that in response to rhIL-1 alpha, there was a higher uptake by the maternal liver and bone marrow with less 65Zn uptake by bone, intestine and plasma activity compared to controls. No change was observed in 65Zn taken up by the placenta or transferred to the fetus. Alteration of metallothionein gene expression could represent, in part, the mechanism whereby altered effects of zinc metabolism and function are mediated during fetal development.

Effects of maternal iodine deficiency on the L-thyroxine and 3,5,3'-triiodo-L-thyronine contents of rat embryonic tissues before and after onset of fetal thyroid function.

Female rats were placed on a low iodine diet (LID) or LID supplemented with KI. They were mated 3-6 months later. Maternal and embryonic tissues were obtained both before the onset of fetal thyroid function, at 11 and 17 days of pregnancy, and at 21 days of gestation. T4 and T3 concentrations were measured by RIA. T4 concentrations were very low in the plasma, liver, and lung of LID dams and in all embryonic samples obtained from such mothers, namely 11-day-old embryotrophoblasts, 17-day-old placentas and embryos, 21-day-old placentas, embryos, plasma, liver, lung, and carcass (whole embryos minus the trachea, thyroid, blood, liver, and brain). T3 was low in 17-day-old placentas and embryos and in all fetal tissues obtained at 21 days of gestation from LID dams. These results show that when iodine deficiency is severe enough to result in very low maternal plasma T4 levels, embryonic tissues are deficient in T4 and T3 both before and after the onset of fetal thyroid function. This finding might be relevant to the etiopathology of human iodine deficiency disorders.

Pharmacological studies on the potentiation of phenytoin teratogenicity by acetaminophen.

An in vivo murine model was developed to measure maternal phenytoin biotransformation along with the covalent binding of phenytoin to fetal tissues in the same fetuses which were assessed for fetal anomalies. Acetaminophen was administered to pregnant CD-1 mice 1 hour prior to phenytoin, both given i.p. at varying doses and gestational times between days 11 and 13. Dams were killed between days 12 and 19. Metabolites reflecting the enzymatic bioactivation of phenytoin were quantified in maternal plasma and urine with high-performance liquid chromatography (HPLC). Acetaminophen pretreatment caused a threefold increase in phenytoin-induced fetal cleft palates without increasing resorptions. The covalent binding of radiolabeled phenytoin to fetal and placental tissues measured on day 13 was increased twofold and threefold, respectively, by acetaminophen pretreatment. Phenytoin covalent binding measured on day 16 was significantly increased in the livers of fetuses with cleft palates, but not in the livers of dams with fetuses having cleft palates. Binding to fetal brain on day 16 was over fourfold higher than that in maternal brain. Acetaminophen pretreatment differentiated dams into poor and extensive metabolisers of phenytoin, with only the latter group carrying fetuses with cleft palates. The incidence of fetal cleft palates correlated positively with maternal urinary levels of phenytoin (r = +.81, P less than .01) and its dihydrodiol metabolite (r = +.61, 0.05 less than P less than .1), and negatively with levels of para-hydroxylated phenytoin (r = -.85, P less than .01). These findings related both to the mechanism of phenytoin teratogenicity and its potentiation by acetaminophen.

Diazepam metabolism in the guinea pig materno-fetal model: effects of cigarette smoke.

The transplacental acquisition, disposition and biotransformation of diazepam (DZ) was investigated in the pregnant guinea pig at 65-67 days of gestation following the administration of single oral doses of 10 mg/kg body weight, the dams and fetuses being euthanized 60 min post-treatment. Tissues (blood plasma, liver, brain, perirenal fat and placenta) were removed for drug residue analysis. Nordiazepam (NDZ) was the only metabolite produced by guinea pigs in vivo. Residues of DZ and NDZ were found in fetal tissues, indicating that the placenta was not an effective barrier. The influence of cigarette smoke on in vitro DZ biotransformation was studied by exposing pregnant guinea pigs (55-57 days of gestation) to ambient air (control) or cigarette smoke thrice daily for 10 consecutive days. At term (day 67), the fetuses were delivered by caesarean section for the preparation of hepatic and placental microsomes to measure the metabolism of DZ. DZ was converted at a slow rate into NDZ by fetal hepatic and placental microsomes in vitro. Exposure to cigarette smoke had no effect on DZ metabolism by the dam liver or by the placenta but a 2-4-fold increase in NDZ formation was observed in fetal hepatic microsomes.

Vitamin a during Lactation: Relationship of Maternal Diet to Milk Vitamin a Content and to the Vitamin a Status of Lactating Rats and their Pups

We have investigated the effects of maternal vitamin A intake during pregnancy and lactation or during lactation alone on the concentration of vitamin A in rat’s milk and on vitamin A levels in plasma and liver of dams and their pups. Groups of Sprague-Dawley rats were fed diets having either a high vitamin A content [15 retinol equivalents (R.E.)/g diet] or a low vitamin A content (0.6 R.E./g) for 42 d, including 7–8 d prior to pregnancy, pregnancy, and for 14 d of lactation. The concentration of vitamin A in milk on d 14 of lactation was significantly greater on the high vitamin A diets [114 ± 16 µg/dl (mean ± SEM; n = 8) versus 52 ± 7.3 µg/dl (n = 11), P < 0.005]. However, milk vitamin A concentration on d 1 of lactation did not vary with maternal vitamin A intake during pregnancy. In a second study in which supplementation with vitamin A (30 R.E./g diet) was begun on d 1 postpartum, the milk vitamin A content increased progressively with duration of lactation. Maternal plasma vitamin A concentrations did not differ between rats fed the higher or lower vitamin A diets. However, liver vitamin A concentrations both of dams and of their 14-d-old pups were significantly higher when dams were fed the higher vitamin A diets during pregnancy and/or lactation. The results of these studies indicate that the transfer of vitamin A from mother to offspring by milk and the vitamin A status of dams and their suckling neonates is influenced by maternal vitamin A intake during lactation. This occurs at levels of dietary vitamin A that maintain plasma vitamin A concentrations within the normal range.

Effects of acute or chronic polychlorinated biphenyl ingestion on maternal metabolic homeostasis and on the manifestations of embryotoxicity caused by cyclophosphamide in mice.

Diets of mice contained Aroclor 1254 (PCBs; 0, 1, 10 or 100 ppm). Some groups ingested PCBs beginning on gestation day (gd) 6 (vaginal plug positive day = gd 0) and continuing throughout pregnancy (acute exposure). Others were put on PCBs 90 days before mating and continued (chronic exposure) until all animals were sacrificed on gd 18. None of the PCBs diets had adverse effects on offspring. Chronic ingestion of 100 ppm reduced the conception rate. All chronic and acute 100 ppm pregnant mice had significantly altered ratios of liver to body weight. The aim of the different pretreatment regimens was to affect to variable degrees metabolism of cyclophosphamide (CPA). Bioactivation in the dam's liver is a prerequisite for embryotoxic effects in mice. Two doses of CPA were selected that caused malformations in 21.6% (10 mg/kg) or 93.4% (16 mg/kg) of the fetuses when injected on gd 11. The interaction (enhancement, no effect, attenuation) between acute or chronic PCBs and CPA could thus be examined. Double stained fetal limbs and their bone lengths were evaluated. The observations were correlated with cytochrome P-450, the levels of which were elevated in all 100 ppm groups. The activities of enzymes coupled to this hemoprotein family were induced in maternal liver in an exposure mode and PCBs concentration-dependent manner. Body burdens of PCBs in dams and fetuses were related to diet levels in acutely, but not in chronically treated animals. Placental transfer of radioactivity from ring-labelled 14C-CPA, measured in control and 100 ppm chronic mice, was not significantly affected by PCBs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of specific dietary fatty acids on lipogenesis in the livers and mammary glands of lactating mice.

The effects of linoleic, linolenic and columbinic acids fed as 4% of a high carbohydrate (50% glucose) diet on the activities and the amounts of several enzymes associated with fatty acid synthesis in livers and mammary glands of lactating mice were compared with those for stearic and oleic acids. Fatty acid synthesis, measured in vivo, was significantly lower in livers of mice ingesting all 3 polyunsaturated fatty acids (PUFA), whereas in mammary glands synthesis was lower only in mice receiving columbinic acid. The activities of fatty acid synthetase (FAS) and acetyl CoA carboxylase were significantly reduced in liver by all 3 PUFA, as wee activities of glucose-6-phosphate dehydrogenase, malic enzyme (ME) and citrate cleavage enzyme (CCE), also associated with lipogenesis. In mammary gland, on the other hand, the activities of these enzymes were unaffected by dietary PUFA. The tissue contents of FAS, ME and CCE, measured by rocket immunoelectrophoresis, were found to be significantly reduced in liver by linoleate, linolenate and columbinate but were not significantly altered in mammary gland. The decrease in hepatic lipogenesis observed was principally due to a decrease in the amounts of these enzymes induced by the dietary PUFA but the inhibition in mammary gland caused by columbinate could not be accounted for by a reduction in enzyme contents and therefore may be due to allosteric effects which occur when fatty acid synthesis is measured with 3H2O. The fatty acid composition in liver and mammary gland of dams and in liver and kidney of pups completely reflected dietary fatty acids. Columbinate made up ca. 20% of the total fatty acids in both tissues of the columbinic acid-fed mice and ca. 15% in the pup tissues. This suggests that columbinate is incorporated into milk lipids of dams and is easily absorbed by pups. The elevated ratios of 16/16:1 and 18/18:1 in liver and mammary gland of dams and liver and kidney of the pups from dams fed linoleate, linolenate and columbinate suggest that each of these polyunsaturated fatty acids in the diet can inhibit the activity of delta 9 desaturase.

Experimental Infection of Pregnant Gilts with Leptospires Isolated from British Wildlife. II. Clinical, Bacteriological and Pathological Aspects of Infection

Groups of pregnant gilts were experimentally infected with four different leptospiral serovars, muenchen, bratislava, copenhageni and in isolate belonging to the Pomona serogroup, isolated from British wildlife. Inoculations took place as near as possible to day 70 of gestation. In non-aborting gilts, full-term foetuses were delivered by hysterectomy to facilitate full clinical, serological and bacteriological examinations. All gilts were susceptible to infection with the respective serovars and some pigs exhibited mild clinical symptoms during the acute stage of infection. Reproductive disease was produced only in those infected with the Pomona serogroup isolate where abortions of dead and mummified foetuses occurred from day 27 to day 33 post inoculation, and the dams exhibited leptospiruria of high intensity until the end of the experiment. Leptospiruria in gilts infected with other serovars was of lower intensity and was inconstant. Radiographic assessment of the age of the aborted foetuses indicated that the time of death in utero had a wide range within each litter, and abortions occurred from five to six days after mean death times. Leptospires of the Pomona serogroup were isolated from foetuses aborted by infected gilts, but serological and bacteriological examination of full-term foetuses from dams inoculated with muenchen, bratislava and copenhageni revealed no evidence of transplacental infection. Histological examination of the liver and kidneys of dams at the termination of the experiment revealed evidence of maternal disease in all groups of pigs. Renal lesions were most severe in gilts infected with the Pomona serogroup isolate, and consisted predominantly of mononuclear cell infiltration of the renal interstitium, and degeneration and death of tubular cells. Renal lesions in gilts infected with muenchen, bratislava and copenhageni consisted predominantly of mild glomerular and tubular damage.

Influence of Maternal Magnesium Deficiency on Tissue Lead Content of Rats

Diets containing 150 or 600 ppm magnesium with or without 200 ppm lead were fed to rats throughout gestation and lactation to determine the influence of moderate magnesium deficiency on tissue lead content of maternal and offspring tissue. During lactation it was necessary to increase the lowest dietary magnesium level to 225 ppm. Lead caused a significant depression in both gestational weight gain and average pup weight regardless of the level of dietary magnesium. Maternal magnesium deficiency was evidenced by significant reductions in serum and tibia magnesium, a 17-fold increase in kidney calcium, and hyperemia of the ears. In offspring, however, only growth and tibia magnesium were significantly affected by the magnesium deficiency, and the maternal-fetal difference in serum and tibia magnesium concentration was maintained. Maternal magnesium deficiency resulted in significantly higher lead concentrations in dam liver, and offspring erythrocytes, liver and tibia. A mechanism for the enhanced accumulation of lead in maternal and offspring tissue as a result of maternal magnesium deficiency is not defined, but it is likely to involve enhanced intestinal lead absorption.

Iron status of suckling rats as influenced by maternal diet during gestation and lactation.

1. Two experiments are reported. In Expt 1, pregnant Sprague-Dawley rats (200-220 g) were given purified diets containing 35, 75, 150 or 300 mg Fe/kg throughout gestation and lactation. In Expt 2, the levels of Fe given were 250 and 300 mg/kg diet. 2. Litters were standardized at birth to contain seven pups. On day 20 of lactation blood, milk, spleen and liver were collected for Fe analysis. 3. A dietary Fe concentration of 35 mg/kg maintained maximum weight gain, food intake, liver and spleen weight, haemoglobin concentration and packed cell volume in the growing maternal rat through 20 d of lactation. Dam liver and spleen Fe concentrations were maximized between 75 and 250 mg Fe/kg diet. 4. Pups (20-d-old) nursed by dams given 35 mg Fe/kg tended to have lower body and organ weights compared to other groups. Liver and spleen Fe concentrations increased with increasing maternal dietary Fe and were significantly increased between 150 and 250 mg Fe/kg.

Deposition of copper, manganese, selenium and zinc in the ovine foetus and associated tissues

Merino ewes, some of which were supplemented with copper and selenium, were mated with Merino rams and were slaughtered between 70 and 150 days after mating. Copper, manganese, selenium and zinc were determined in the conceptus and associated tissues. Supplementation with copper and selenium increased the concentration of these elements in the conceptus. Relationships were derived for predicting the quantities of copper, manganese, selenium and zinc in the foetus and conceptus from the age of the foetus, and, in the case of copper and selenium, from their concentration in the dam's liver or blood. The use of these relationships for predicting nutrient requirements for pregnancy is discussed.

Characterization of the Lactation-Dependent Fatty Liver in myo-Inositol Deficient Rats

The characteristics of the lipid deposited during lactation- dependent fatty liver development in mt/o-inositol-deficient rats were studied. After only 4 days of lactation, cholesterol esters and triglycA©ride levels were significantly elevated, whereas liver phospholipid levels were significantly depressed in the livers of mi/o-inositol deficient dams com pared with rats fed mt/o-inositol supplemented diets. Electron microscopy revealed the presence of numerous large intracellular lipid droplets in the livers of dams deprived of mt/o-inositol after 14 days of lactation. Plasma lipoprotein lipid levels were depressed for mt/o-inositol deprived dams during lactation, suggesting a block in hepatic lipoprotein secretion. In addition, elevation of the plasma lipid levels after the onset of mammary involution emphasized the role that lactation and associated hormonal changes may play in the development of this fatty liver. Though not sig nificantly different, elevation of the mean concentration of plasma free fatty acids in mt/o-inositol deficient dams above that of the myo-inositol supplemented dams was also observed during lactation. The contribution of these factors to the development of lactation-induced fatty liver in myo- inositol deficient rats is discussed. In phthalylsulfathiazole containing diets, more than 0.05% mt/o-inositol was required to maintain the liver total lipid levels below 1% by weight after 14 days of lactation. No differences in lipid composition were observed in kidney and intestinal tissues from 21- day lactating dams fed the mi/o-inositol deficient or control diets. J. Nutr. 107: 1871-1883, 1977.

Effects of Malnutrition on Some Aspects of RNA Metabolism in the Maternal Liver and Fetal Tissues at Different Stages of Pregnancy in the Rat

A comparison was made between rats fed diets containing either 5% casein or 25% casein, both being supplemented with DL-methionine, from the first day of pregnancy. Livers of dams killed on days 7, 14, and 21 and whole fetuses on days 12, 14, and 21 were weighed, analyzed for protein, RNA and DNA content and assayed for ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD). Free and total alkaline ribonuclease activity were also measured in the maternal livers. Malnutrition reduced the characteristic increase in content of DNA, RNA and protein in the maternal liver and fetus. In control rats total hepatic RNase activity increased and free RNase activity decreased during late pregnancy. In the deprived group, total activity decreased and free activity increased during late pregnancy. Liver and fetal ODC and SAMD activities were reduced by undernutrition. These studies show that malnutrition reduced both growth and the accretion of RNA in livers and fetuses of rat dams. These changes coincide with a reduced activity of polyamine synthesizing enzymes suggesting that there is a functional relationship between polyamines and RNA. High hepatic free RNase activity in malnourished dams may help to limit any build up in RNA content.

Iron Supplementation of the Lactating Mouse and Suckling Neonates

Iron was administered orally or parenterally to lactating mice in an attempt to supplement their suckling neonates by raising the iron content of their milk. When rodent stock diet was fed, supplementation of lactating dams for 14 to 19 days by repeated intramuscular injection of iron-dextran increased ferritin iron stores significantly in the livers of both dams and sucklings, but hemoglobin concentration remained suboptimal in both dams and neonates unless supplemental copper was provided. Fed 10 HIMFeSO4 in a liquid milk diet (with or without 0.05 mM CuSO4) for 19 days, lactating dams had maximal hemoglobin and stored 40-times more liver ferritin iron than unsupplemented dams; their sucklings developed hemoglobin concentrations that appeared maximal for the neonate and liver rerritin iron stores that were 18-times greater than those in sucklings from unsupplemented dams. Stock diet along with supplemental oral iron (5 HIM ferric citrate polymer) and copper (0.05 mM CuSO4) produced similar results and, in addition, raised maternal ceruloplasmin and neo natal liver copper concentrations above those of unsupplemented mice. Environmental contamination was ruled out as a source of supplemental iron for the sucklings. These data are the first to demonstrate that the iron content of milk can be raised in vivo by supplementation during lactation. Vigorous iron supplementation of the female mouse during lactation can thus be an effective way of maintaining optimal hemoglobin and ferritin iron reserves in both the dam and suckling neonates. J. Nutr. 107: 1377-1384,1977.

The Relative Concentrations of Dam and Fetal Liver Glycogen

The Relative Concentrations of Dam and Fetal Liver Glycogen