Teratogenicity of zinc deficiency in the rat: study of the fetal skeleton

Zinc deficiency (ZD) is teratogenic in rats, and fetal skeletal defects are prominent. This study identifies fetal skeletal malformations that affect calcified and non-calcified bone tissue as a result of gestational zinc deficiency in rats, and it assesses the effect of maternal ZD in fetal bone calcification. Pregnant Sprague-Dawley rats (180-250 g) were fed 1) a control diet (76.4 micrograms Zn/g diet) ad libitum (group C), 2) a zinc-deficient diet (0 microgram/g) ad libitum (group ZD), or 3) the control diet pair-fed to the ZD rats (group PF). On day 21 of gestation, laparotomies were performed. Fetuses were weighed, examined for external malformations, and stained in toto with a double-staining technique for the study of skeletal malformations. Maternal and fetal tissues were used for Zn, Mg, Ca, and P determinations. Gross external malformations were present in 97% of the ZD fetuses. No external malformations were found in fetuses from groups C and PF. Ninety-one percent of cleared ZD fetuses had multiple skeletal malformations, whereas only 3% of the fetuses of group PF had skeletal defects; no skeletal malformations were found in fetuses from group C. Some of the skeletal malformations described in the ZD fetuses, mainly affecting non-calcified bone, were not mentioned in previous reports, thus stressing the importance of using double-staining techniques. Examination of stained fetuses and counting of ossification centers revealed important calcification defects in ZD fetuses. These effects were confirmed by lower Ca and P concentrations in fetal bone with alteration of the Ca:P ratio.     

Zinc-deficient rats have more limited bone recovery during repletion than diet-restricted rats

The objective of this study was to investigate the effects of dietary zinc deficiency and diet restriction on bone development in growing rats, and to determine whether any adverse effects could be reversed by dietary repletion. Weanling rats were fed either a zinc-deficient diet ad libitum (ZD; <1 mg zinc/kg) or nutritionally complete diet (30 mg zinc/kg) either ad libitum (CTL) or pair-fed to the intake of the ZD group (DR; diet-restricted) for 3 weeks (deficiency phase) and then all groups were fed the zinc-adequate diet ad libitum for 3, 7, or 23 days (repletion phase). Excised femurs were analyzed for bone mineral density (BMD) using dual-energy x-ray absorptiometry, and plasma was analyzed for markers of bone formation (osteocalcin) and resorption (Ratlaps). After the deficiency phase, ZD had lower body weight and reduced femur BMD, zinc, and phosphorus concentrations compared with DR; and these parameters were lower in DR compared with CTL. Femur calcium concentrations were unchanged among the groups. Reduced plasma osteocalcin in ZD and elevated plasma Ratlaps in DR suggested that zinc deficiency limits bone formation while diet restriction accelerates bone resorption activity. After 23 days of repletion, femur size, BMD, and zinc concentrations remained lower in ZD compared with DR and CTL. Body weight and femur phosphorus concentrations remained lower in both ZD and DR compared with CTL after repletion. There were no differences in plasma osteocalcin concentrations after the repletion phase, but the plasma Ratlaps concentrations remained elevated in DR compared with CTL. In summary, both ZD and DR lead to osteopenia during rapid growth, but the mechanisms appear to be due to reduced modeling in ZD and higher turnover in DR. Zinc deficiency was associated with a greater impairment in bone development than diet restriction, and both deficiencies limited bone recovery during repletion in growing rats.     

Effect of an acute zinc depletion on rat lipoprotein distribution and peroxidation

The aim of this study was to determine the extent to which zinc depletion leads to lipoprotein modifications by measuring both lipoprotein-fraction distribution and peroxidation in zinc-depleted rats. The animals were divided into three groups and fed for 8 wk a zinc-adequate diet (100 ppm) ad libitum (AL), a zinc-deficient diet (0.2 ppm) ad libitum (ZD), or a zinc-adequate diet according to the pair feeding method (PF). Trace-element status, tissular lipids, and lipoprotein-fraction study were performed. The MDA production by the lipoprotein fraction was measured before and after induced peroxidation. Cholesterol and phospholipids were increased in ZD rats. An important increase of VLDL and IDL was observed and a significant enhanced production of MDA by the LDL was related to zinc deficiency. From this observation, we may conclude that LDL fractions of ZD rats are more susceptible to induced oxidative damage. These results suggest that in zinc deficiency, the lipoprotein fragility is an aggravating factor of peroxidation and the dyslipoproteinemia may lead to an atherogenic risk.     

Hepatic insulin binding following in utero exposure to ethanol

Insulin binding to liver membranes has been studied in term fetuses of rats fed ethanol-containing liquid diet during pregnancy . Pair-fed and ad libitum-fed controls received liquid diet in which maltose-dextrins were substituted isocalorically for ethanol. Food consumption and body weigh gain of ethanol- imbibing dams were 35% and 70% less than their ad libitum counterparts respectively. Ethanol-fed rats also exhibited less gain in body weight than pair-fed controls despite isocalorically equivalent food intake. The number of live pups was not different among the various groups; however, liver weight of fetuses exposed to ethanol in utero was 47% less than those of the pups of ad libitum control dams and 28% less than those of the offspring of pair-fed control rats. Insulin binding to liver membranes of fetuses exposed to ethanol in utero was lower than that of ad libitum controls but was not significantly different from that of the pair-fed control animals. Average affinity profiles showed a reduction in K at all levels of receptor occupancy in the fetuses of ethanol-fed rats. For fetuses of the pair-fed group, K was reduced only at fractional occupancy below 20% but not at higher fractional occupancy. Because of the similarity of insulin binding in the fetuses of the ethanol-fed rats and their pair-fed counterparts, effects of ethanol on insulin binding cannot account for the reduced hepatic glycogen stores previously reported in term fetuses.     

Effect of maternal alcohol consumption on the fetal thyroid in the rat

To investigate the effect of maternal alcohol consumption on the development of the fetal thyroid gland, Sprague-Dawley rats were given 20% ethanol for 4 weeks prior to mating and 30% ethanol throughout gestation. Pair-fed controls received an isocaloric amount of corn starch and chow, with water ad libitum, and ad libitum controls received rat chow and water. On Days 17, 18, 19, and 20 of gestation, the fetuses were weighed and the fetal thyroids were removed for histometric observation. On Days 19 and 20, the fetal thyroids of alcohol-exposed fetuses weighed significantly less than those of the two control groups, but more than the control thyroids 1 day earlier. Maternal alcohol consumption caused a significant decrease in both the follicular cell height and the follicle diameter of the fetal thyroid on all days examined. In the alcohol group on Days 19 and 20 of gestation, the cell height was less than, and the follicle diameter was approximately equal to those in the two controls 2 days earlier. These results indicate that, as a consequence of maternal alcohol consumption, growth of the fetal thyroid gland is retarded, and there are indications of fetal hypothyroidism, as seen from the histometric data. This latter is suggestive of a retarded thyrotropic activity of the fetal pituitary gland.     

Maternal diets enriched in olive oil regulate lipid metabolism and levels of PPARs and their coactivators in the fetal liver in a rat model of gestational diabetes mellitus

In a rat model of gestational diabetes mellitus (GDM) programmed in the offspring of neonatal streptozotocin-induced (nSTZ) diabetic rats, lipids are accumulated in the fetal liver in a sex-dependent way. Here, we evaluated whether maternal diets enriched in olive oil in rats that will develop GDM ameliorate lipid metabolic impairments in the fetal livers. Pregnant offspring of control and nSTZ diabetic rats (F0) were fed a 6% olive oil-supplemented diet throughout the F1 gestation. We evaluated maternal metabolic parameters as well as lipid content, expression of lipid metabolizing enzymes and protein expression of PLIN2, PPARs and PPAR coactivators in the fetal livers. The offspring of nSTZ diabetic rats developed GDM regardless of the maternal treatment. Hypertriglyceridemia in GDM rats was prevented by the olive oil-enriched maternal treatment. In the livers of male fetuses of GDM rats, the maternal olive oil-supplemented diet prevented lipid overaccumulation and prevented the increase in PPARγ and PPARδ levels. In the livers of female fetuses of GDM rats, the maternal olive oil supplementation prevented the increase in PPARδ levels and the reduction in PGC1α levels, but did not prevent the reduced lipid content. Control and GDM rats showed a reduction of lipid metabolic enzymes in the fetal livers, which was associated with reduced levels of the PPAR coactivators PGC-1α and SRC-1 in males and of SRC-1 in females. These results suggest powerful effects of a maternal olive oil-supplemented diet in the fetal liver, possibly providing benefits in the fetuses and offspring from GDM rats.     

Adaptive changes in enzyme activity and metabolic pathways in adipose tissue from meal-fed rats

A number of metabolic factors and the activity of a number of enzymes were determined in meal-fed (animals fed a single daily 2 hr meal) and nibbling (ad libitum-fed) rats. The dependency of the observed adaptive changes on the ingestion of carbohydrate was studied by feeding diets high in carbohydrate or fat. Glucose-6-phosphate dehydrogenase and NADP-malic dehydrogenase were more active in adipose tissue from high carbohydrate meal-fed rats than in tissue from ad libitum-fed rats. The activity in adipose tissue of isocitric dehydrogenase, 6-phosphogluconate dehydrogenase, and NAD-malic dehydrogenase did not increase significantly in response to meal-feeding the high carbohydrate diet. No increase in lipogenesis or enzyme activity could be demonstrated in adipose tissue from rats meal-fed a high fat diet. Lipase activity of adipose tissue was increased by high carbohydrate meal-feeding and decreased by feeding a high fat diet. The in vitro uptake of palmitate-1-(14)C by adipose tissue was depressed by a high fat diet and enhanced in rats meal-fed a high carbohydrate diet. Diaphragm or slices of liver from high fat-fed rats oxidized palmitate-1-(14)C more rapidly than did tissue from ad libitum-fed animals. Evidence is presented for the quantitative importance of citrate as a source of extramitochondrial acetyl CoA in adipose tissue of meal-eating and ad libitum-fed rats. The relationship of extramitochondrially formed citrate to the NAD-malic dehydrogenase-malic enzyme system in adipose tissue is discussed.     

Effects of the beta3 adrenergic receptor agonist on developmental obesity in oophorectomized rats.

In this study, we evaluated the anti-obesity effects of selective beta3 adrenergic receptor agonist (ARa) and/or a diet in oophorectomized (OVX) treatment in obese rats. Ten-week-old female Sprague-Dawley rats were divided into 4 groups: (1) OVX; (2) OVX treated with beta3 ARa, BRL 35 135; (3) sham-operated controls (sham group); (4) sham-treated with beta3 ARa (sham+ARa group). These four groups were divided into two groups, one on ad libitum diet, and the other on a diet of limited chow. The effects of beta3 ARa on body weight, intraabdominal fat weight, adipocyte volume, serum lipid content, and serum leptin were measured after 4 weeks had been completed. On both the ad libitum and the limited diet, ARa significantly reduced the ratio of intraabdominal fat and body weight (IAF ratio) regardless whether in the OVX or sham group, although ARa had no influence on weight gain. On the ad libitum diet, the serum leptin was significantly increased after OVX, and significantly reduced after ARa administration. ARa significantly reduced the volume of intraabdominal adipocytes. We conclude that ARa reduces intraabdominal fat without reducing body weight in oophorectomized rats. The serum parameter affected differently to rats on the ad libitum diet and on the limited diet.     

Dietary zinc deficiency decreases plasma concentrations of vitamin E

Experiments were conducted to examine the effects of dietary zinc (Zn) upon plasma vitamin E (E) concentrations to test the hypothesis that there may be a significant dietary interaction between these two nutrients. Weanling female Sprague-Dawley rats were fed diets that were (i) Zn-deficient (less than 0.9 micrograms Zn/g diet) ad libitum; (ii) Zn-adequate (50.9 micrograms Zn/g diet), pair-fed to the Zn-deficient group; and (iii) Zn-adequate (50.9 micrograms Zn/g diet) ad libitum. Plasma E in Zn-deficient animals (4.02 +/- 1.20 micrograms/ml) was significantly reduced (P less than or equal to 0.05) compared with results in both Zn-adequate pair-fed (9.21 +/- 0.70 micrograms/ml) and Zn-adequate ad libitum-fed (9.47 +/- 0.90 micrograms/ml) animals. Zn deficiency in this model system also resulted in significant (P less than or equal to 0.05) reductions in femur and plasma Zn concentrations as well as in plasma retinol, plasma triglyceride, and plasma cholesterol concentrations. Plasma albumin and total plasma protein concentrations were normal in Zn-deficient animals. With dietary Zn deficiency, the decrease in plasma E appeared to be out of proportion to associated decreases in plasma triglyceride and plasma cholesterol concentrations. Since E is associated with plasma lipoproteins, these data suggest that lipid and/or E malabsorption may be a consequence of Zn deficiency. In response to increased dietary intake of E, increments of plasma E were lower in Zn-depleted than in Zn-adequate, pair-fed animals. These findings suggest that dietary Zn deficiency possibly may increase the nutritional requirement for E necessary to maintain adequate plasma concentrations.     

Long-term effects of lactational zinc deficiency on bone mineral composition in rats fed a commercially modified Luecke diet

The purpose of this study was threefold: 1. to determine the long-term effects of interactions between lactational zinc deficiency and gender on bone mineral composition in repleted rat offspring, 2. to determine the nutritional efficacy of the second of two commercially designed, modified Luecke diets (ML2) during the gestational and lactational stress, and 3. determine the ultratrace element contents of Ralston Rodent Laboratory Chow #5001. The ML2 basal diet, based on dextrose, sprayed egg white, and corn oil contained 0.420 μg Zn/g, was supplemented with Zn (as zinc acetate) at 0 (diet 0ML2) or 30 (diet 30ML2) μg/g, and was mixed and pelleted commercially. all rat dams were fed the 30ML2 diet ad libitum during gestation. Beginning at parturition, the dams were fed either the 1. 0ML2, 2. 30ML2 (food restricted), or 3. 30ML2 (ad libitum) diets. All pups were fed the 30ML2 diet ad libitum from 23 to 40 d of age. From d 40 to 150, all pups were fed Ralston Rodent Laboratory Chow. The 30ML2 diet was found to be nutritionally efficacious; litter size and pup growth were normal and pup mortality was only 1.2%. Pups (ZD) with access to the 0ML2 diet until 23 d of age and nursed by dams fed the 0ML2 diet, when compared to pups (PF) fed restricted amounts of the 30ML2 diet, exhibited increased mortality and decreased concentrations of tibial zinc but no change in growth. Inadequate zinc nutriture during infancy, despite postlactational zinc repletion, induced imbalances in adult bone mineral metabolism. Thus, at 150 d of age, the ZD pups exhibited increased levels of bone P and Mg and decreased concentrations of K as compared to the PF pups.     

Studies on the pathophysiology of acute renal failure. II. A histochemical study of the proximal tubule of the rat following administration of mercuric chloride.

Acute renal failure was induced in male rats by the subcutaneous injectioon of 4 mg HgC12 per kg body weight. Enzyme activities of the proximal tubule were studied histochemically at six time intervals from 15 min to 24 h. The enzyme studied were alkaline phosphatase, 5'-nucleotidase, acid phosphatase, alpha-glycerophosphate dehydrogenase (NAD-independent), malic dehydrogenase, succinic dehydrogenase, latic dehydrogenase, glucose-6-phosphate dehydrogenase and glucose-6-phosphatase. Decreases in activity were observed for alkaline phosphatase and 5'-nucleotidase after 15 min. Acid phosphatase was decreased after 30 min. These three enzymes returned to control levels after 3 h, but malic dehydrogenase and alpha-glycerophosphate dehydrogenase were decreased at this time interval. Succinic dehydrogenase was first decreased after 6 h. The earliest morphological changes detectable by light microscopy were observed in pars recta tubules in the medullary rays after 6 h, a time when all enzymes studied showed widespread decreased activity throughout the proximal tubule. After 24 h, the pars convoluta appeared morphologically normal but the pars recta was necrotic and exhibited calcification, whereas enzyme activity was decreased (absent in some cases) in both pars convoluta and pars recta. These results support the hypothesis that Hg++, when given in a sublethal dose, is associated with early histochemical changes in the brush border of the proximal tubule, which may be related to early changes in sodium reabsorption and to the subsequent development of acute renal failure. The observation that changes in plasma membrane-associated enzymes occur early and prior to alterations in enzymes of mitochondria and the endoplasmic reticulum suggests that Hg++ interacts initially with the plasma membrane.     

Influence of caloric restriction and exercise on tumorigenesis in rats

Underfeeding or caloric restriction have been shown to inhibit the growth of spontaneous, transplanted, or chemically induced tumors in rats and mice. At 40% caloric restriction, growth of 7,12-dimethylbenz(a)anthracene-induced mammary and 1,2-dimethylhydrazine-induced colonic tumors is inhibited significantly even when the restricted diet contains twice as much fat as the control diet. Some inhibitory effects become evident even at 10% caloric restriction. In studies involving high fat diets, we find that rats receiving 20% fat ad libitum exhibit significantly higher 7,12-dimethylbenz(a)anthracene-induced mammary tumor incidence, multiplicity, and weight than rats ingesting the same amount of fat daily, but in a diet containing 25% fewer calories. In a study of intermittent ad libitum and restrictive feedings, chemically induced tumorigenicity varies inversely with feed efficiency. Exercise has also been shown to inhibit tumor growth. Sedentary rats fed ad libitum have a 108% higher incidence of 1,2-dimethylhydrazine-induced colon tumors than rats fed ad libitum but subjected to vigorous treadmill exercise. Caloric flux (either reduced intake or increased outflow) appears to reduce tumorigenicity in rodents.     

Expression of metallothionein in the liver and kidney of rats is influenced by excess dietary histidine

It is well known that excess dietary histidine induces the metabolic changes in copper and zinc. Therefore, this study was carried out to clarify whether excess dietary histidine alters the gene expressions of metallothionein-1 and metallothionein-2 in the liver and kidney. Male rats were fed the control (ad libitum and pair-fed) or histidine-excess (50 g of L-histidine per kg of diet) diet for 0, 1 and 3 days. The levels of liver metallothionein-1 and metallothionein-2 mRNA were markedly lower in the rats fed the histidine-excess diet as compared to those of the control (ad libitum and pair-fed) diet, when fed for 1 or 3 days. The levels of renal metallothionein-1 and metallothionein-2 mRNA in the rats fed the histidine-excess diet were higher or tended to be higher as compared with the rats fed the control (ad libitum and pair-fed) diet when fed for 1 or 3 days, respectively. At the same time, hepatic copper content was decreased and renal zinc content was increased by dietary histidine. It thus appears, that such a response on the level of liver metallothionein mRNA might be related to the contents of liver copper, but of kidney metallothionein mRNA might be due to the content of zinc.     

Zinc deficiency does not enhance LDL uptake by P 388 D1 macrophages in vitro

The aim of the study was to investigate the effect of zinc depletion on the susceptibility of Wistar rat low-density lipoproteins (LDL) to peroxidation and their uptake by macrophages, before and after in vitro oxidation. The rats were fed for 7 wk a Zn-adequate diet (100 ppm) ad libitum (AL), a Zn-deficient diet (0.2 ppm) ad libitum (ZD), or a Zn-adequate diet according to the pair-feeding method (PF). Zinc status was determined and, for each group, blood was pooled, and LDL were isolated and labeled with¹²⁵Iodine. An aliquot of each LDL sample was oxidized using Fe^II 10 μM/ascorbate 250 μM. Oxidized and nonoxidized (native) LDL were incubated with P 388 D1 macrophages, and their rates of uptake and degradation by macrophages were measured. Before oxidation, LDL uptake and degradation were not modified by the diet, suggesting that Zn deficiency did not modify rat LDL in vivo. After oxidation, both LDL uptake and degradation were significantly enhanced in the three groups. Nevertheless, we did not observe a significant effect of Zn deficiency. This observation suggests that, in our experimental conditions, Zn deficiency did not modify LDL catabolism.     

Effects of zinc deficiency on morphogenesis of the fetal rat eye

Maternal zinc deficiency during pregnancy results in a high frequency of fetal eye malformations in the Long-Evans rat. In this study we examine the development of the eye from days 12 through 21 of gestation in conceptuses of dams fed deficient or adequate levels of zinc and also examine maternal plasma and conceptus zinc concentrations during this period. Dams were fed diets containing 0.5 (0.5 Zn group), 4.5 (4.5 Zn group), or 100 (100 Zn AL group) micrograms zinc per gram diet ad libitum, or 100 micrograms zinc g-1 diet in amounts restricted on a daily basis to the intake of matched animals from the 0.5 Zn group (100 Zn RI group). Conceptuses were removed and maternal plasma was collected on days 12, 14, 16, 19 and 21 of gestation. Maternal plasma and conceptus zinc concentrations reflected maternal dietary zinc level, with dam plasma Zn concentrations in the order of 0.5 Zn group less than 4.5 Zn group less than 100 Zn group on all days. A similar pattern held for embryo/fetus zinc, except for days 19 and 21, at which times the 0.5 Zn and 4.5 Zn fetuses had similar zinc concentrations. Histological examination of the developing eye of 0.5 Zn fetuses on days 12 and 14 revealed that invagination of the optic cup was often deficient, and that closure of the choroid fissure did not occur, resulting in colobomata and retinal folding visible at term. A very few fetuses were found at term to be anophthalmic or have only remnants of ocular tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of age and dietary restriction on protein synthesis by isolated kidney cells

The influence of age and food restriction on kidney protein synthesis was studied in Fischer F344 rats. The rate of total protein synthesis by suspensions of kidney cells declined 60% between 4 and 31 months of age. The rate of protein synthesis by kidney cells isolated from 19-month old rats fed a restricted diet (60% of diet consumed by rats fed ad libitum) was 45% higher than the rate of protein synthesis by kidney cells isolated from 19-month old rats fed ad libitum. The excretion of protein in the urine was measured to assess the effect of the age related decline in protein synthesis on kidney function. A dramatic increase in proteinuria was observed with increasing age, and rats fed the restricted diet excreted significantly less protein in the urine than rats fed ad libitum.     

In utero glucocorticoid exposure reduces fetal skeletal muscle mass in rats independent of effects on maternal nutrition

Maternal stress and undernutrition can occur together and expose the fetus to high glucocorticoid (GLC) levels during this vulnerable period. To determine the consequences of GLC exposure on fetal skeletal muscle independently of maternal food intake, groups of timed-pregnant Sprague-Dawley rats (n = 7/group) were studied: ad libitum food intake (control, CON); ad libitum food intake with 1 mg dexamethasone/l drinking water from embryonic day (ED)13 to ED21 (DEX); pair-fed (PF) to DEX from ED13 to ED21. On ED22, dams were injected with [(3)H]phenylalanine for measurements of fetal leg muscle and diaphragm fractional protein synthesis rates (FSR). Fetal muscles were analyzed for protein and RNA contents, [(3)H]phenylalanine incorporation, and MuRF1 and atrogin-1 (MAFbx) mRNA expression. Fetal liver tyrosine aminotransferase (TAT) expression was quantified to assess fetal exposure to GLCs. DEX treatment reduced maternal food intake by 13% (P < 0.001) and significantly reduced placental mass relative to CON and PF dams. Liver TAT expression was elevated only in DEX fetuses (P < 0.01). DEX muscle protein masses were 56% and 70% than those of CON (P < 0.01) and PF (P < 0.05) fetuses, respectively; PF muscles were 80% of CON (P < 0.01). Muscle FSR decreased by 35% in DEX fetuses (P < 0.001) but were not different between PF and CON. Only atrogin-1 expression was increased in DEX fetus muscles. We conclude that high maternal GLC levels and inadequate maternal food intake impair fetal skeletal muscle growth, most likely through different mechanisms. When combined, the effects of decreased maternal intake and maternal GLC intake on fetal muscle growth are additive.     

Altered mitochondrial apoptotic pathway in placentas from undernourished rat gestations

Maternal undernutrition (MUN) during pregnancy results in intrauterine growth-restricted (IUGR) fetuses and small placentas. Although reduced fetal nutrient supply has been presumed to be etiologic in IUGR, MUN-induced placental dysfunction may occur prior to detectable fetal growth restriction. Placental growth impairment may result from apoptosis signaled by mitochondria in response to reduced energy substrate. Therefore, we sought to determine the presence of mitochondrial-induced apoptosis under MUN and ad libitum diet (AdLib) pregnancies. Pregnant rats were fed an AdLib or a 50% MUN diet from embryonic day 10 (E10) to E20. At E20, fetuses and placentas from proximal- and mid-horns (extremes of nutrient/oxygen supply) were collected. Right-horn placentas were used to quantify apoptosis. Corresponding left-horn placentas were separated into basal (hormone production) and labyrinth (feto-maternal exchange) zones, and protein expression of the mitochondrial pathway was determined. Our results show that the MUN placentas had significantly increased apoptosis, with lower expression of cytosolic and mitochondrial anti-apoptotic Bcl2 and Bcl-X(L), and significantly higher expression of pro-apoptotic Bax and Bak especially in the labyrinth zone. This was paralleled by higher coimmunostaining with the mitochondrial marker manganese superoxide dismutase (MnSOD), indicating transition of pro-apoptotic factors to the mitochondrial membrane. Also, cytosolic cytochrome c and activated caspases-9 and -3 were significantly higher in all MUN. Conversely, peroxisome proliferator-activator receptor-γ (PPARγ), a member of the nuclear receptor family with anti-apoptotic properties, was significantly downregulated in both zones and horns. Our results suggest that MUN during rat pregnancy enhances mitochondria-dependent apoptosis in the placenta, probably due to the downregulation of PPARγ expression.     

Effect of Undernutrition on Tryptophan and Tyrosine Hydroxylases in the Developing Rat Brain

Rats born to well-fed mothers (20% protein diet ad libitum), protein-restricted mothers (7.5% protein diet ad libitum) or pair-fed with protein-restricted mothers were killed on days 0, 7, 14, 21, 28 and 35 and activities of the two enzymes of neurotransmitter synthesis, tryptophan-5-hydroxylase (EC 1.14.16.4) and tyrosine hydroxylase (EC 1.14.16.2) were assayed. Enzyme activities in normal animals were low at birth and progressively increased to reach adult levels by day 15. Protein-restricted and pair-fed animals also showed a similar pattern. However, significantly higher activities were observed from day 15 onwards in both experimental groups.