15th Day Of Pregnancy Research Articles

Comparison of effects of prenatal administration of dexamethasone and ambroxol on expression of Toll-like receptor 4 of fetal and neonatal rats

Objective To investigate the role of prenatal single-dose administration of dexamethasone and ambroxol on the expression of Toll-like receptor 4 (TLR4) of fetal and neonatal rats. Methods Fifty-four pregnant rats were randomly divided into three groups with eighteen rats in each group:rats treated with 0.2 mg/kg dexamethasone (group 1),0.2 mg/kg dexamethasone and 100 mg/kg ambroxol (group 2),or saline(controls) on the 17th day of gestation.The lung tissues of the offsprings were harvest independently on the 19th day of gestation,the postnatal 3 days and 7 days.The expressions of TLR4 in fetal/neonatal rat lungs of each pregnant rat were analyzed by reverse transcription-polymerase chain reaction(RT-PCR),immunohistochemistry stain,and Western blot. ANOVA and two independent samples t-test were applied. Results On the 19th day of pregnancy,TLR4 mRNA expression was up-regulated in lungs of the two treatment groups compared with controls(controls:0.26 ± 0.18,group 1:0.39 ± 0.21,t =5.866,P＜ 0.05 ; control:0.27 ± 0.22,group 2:0.46 ± 0.13,t =9.572,P＜ 0.01 ).TLR4 mRNA expression was up-regulated in group 2 compared with controls on the postnatal 3 days and 7 days(postnatal 3 d:0.59 ± 0.23 and 0.47 ±0.24,t=2.295,P＜0.05;postnatal 7 d:0.52±0.12 and 0.35±0.17,t=4.219,P＜0.05),while no significant difference was found in group 1 compared with the controls(postnatal 3 d:0.45±0.22 and 0.44±0.14,t=0.128,P＞0.05; postnatal 7 d:0.40±0.16 and 0.36 ±0.12,t=1.365,P＞0.05).Results of the immunohistochemistry demonstrated that on the 19th day of pregnancy,the protein expression of TLR4 was significantly increased in the two treatment groups (controls:0.20 ± 0.29,group 1:0.35±0.32,t=7.179,P＜0.05 ;controls:0.20±0.29,group 2:0.39±0.25,t=10.764,P＜0.01).The protein expression of TLR4 was significantly increased in group 2 on the postnatal 3 days and 7 days(postnatal 3 d:0.55±0.32 and 0.37±0.18,t=7.121,P＜0.05;postnatal 7 d:0.41±0.29and 0.25±0.24,t=6.355,P＜0.05),while no notable difference was found between group 1 and the control (postnatal 3 d:0.40±0.21 and 0.37±0.18,t=0.683,P＞0.05 ;postnatal 7 d:0.28±0.31 and 0.25±0.24,t=0.462,P＞0.05).Results of the Western blot demonstrated that on the 19th day of pregnancy,the protein expression of TLR4 was significantly increased in the two treatment groups (controls:0.15 ± 0.12,group 1:0.27± 0.20,t =7.835,P＜0.05; controls:0.16 ± 0.18,group 2:0.34±0.16,t=10.470,P＜0.01).The protein expression of TLR4 was significantly increased in lungs of the combination administration group on the postnatal 3 days and 7 days(postnatal 3 d:group 2:0.37±0.20 and 0.25±0.22,t=6.379,P＜0.05; postnatal 7 d:0.35±0.15 and 0.24±0.13,t=5.152,P＜0.05),while no notable difference could be found between group 1 and the control (postnatal3 d:0.32±0.26 and 0.25±0.16,t=1.167,P＞0.05; postnatal 7 d:0.29±0.19 and 0.24±0.10,t =1.248,P ＞ 0.05 ). Conclusions Prenatal single-dose administration of dexamethasone may up-regulate the expression of TLR4 in the rat fetal lung.The up-regulation of TLR4 might be one of the critical factors for glucocorticoid-induced maturity of fetal lung.Prenatal single-dose administration of dexamethasone and ambroxol may have effects on the regulation of TLR4 not only in fetal rats,but also in neonatal rats. Key words: Dexamethasone; Ambroxol; Lung; Toll-like receptor 4; Fetal organ maturity; Rats

Effect of bacterial endotoxin on migration of gonadotropin-releasing hormone-producing neurons in rat embryogenesis

The effect of bacterial lipopolysaccharide endotoxin (LPS), immune system activator, on differentiation and migration of gonadotropin-releasing, hormone producing neurons in rat embryogenesis has been studied. Intraperitoneal introduction of LPS (18 jg/kg) to pregnant rats on the 12th day of pregnancy led to 50% decrease in total number of GRH-neurons in the forebrain of 17-day-old embryos and 17% decrease in 19-day-old embryos. At the same time, the number of GRH-neurons in the nasal area of the head of 17- and 19-day-old embryos increased by 40 and 50%, respectively, whereas it increased by 20% in olfactory bulbs of 17-day-old embryos and did not changed in olfactory bulbs of 19-day-old embryos. Neither the total number of neurons nor their distribution patterns were affected by the introduction of LPS into pregnant rats on the 15th day of pregnancy. Singular localization of GRH-neurons in embryo forebrain was observed after LPS administration, whereas the neurons were located by groups of 3-4 cells in rostral areas. Therefore, at the early stages of pregnancy, LPS was shown to suppress initial stages of differentiation and migration of GRH producing neurons. The effects observed in our study may be mediated by LPS-induced, proinflammatory cytokines.

Effects of oral administration of crude leaf extracts of Aglaia loheri Blanco and Ardisia pyramidalis (Cav.) Pers on mouse embryo morphology and maternal reproductive performance

Aglaia loheri Blanco and Ardisia pyramidalis (Cav.) Pers are both endemic plant species with a variety of bioactive compounds, but remain largely untested for their toxicity, and their effects on maternal reproductive performance and fetal morphology. Inbred ICR mice were orally administered with 10 and 5 mg/ml concentrations for A. loheri, and 10 and 1 mg/ml concentrations for A. pyramidalis from the 8th to the 15th day of pregnancy. Dissection at 16 days post coitum (dpc) showed significant differences in maternal reproductive performance, as estimated by gestation index, % dead implants, % females with resorption, % resorption and % fetus with morphological abnormalities. For A. pyramidalis, the 1 mg/ml extract + vitamin A treatment reduced maternal reproductive performance most significantly, while, for A. loheri, treatment with 10 mg/ml extract, with or without vitamin A, as well as with 5 mg/ml extract only resulted to a 100% resorption. Additionally, maternal hepatotoxicity was observed in mice treated with A. pyramidalis, while significant weight losses among mice treated with higher doses of A. loheri + vitamin A suggests toxicity and synergism with vitamin A. These results suggest that caution must be taken when taking these extracts during pregnancy due to their possible toxicity and teratogenicity. Key words: Aglaia loheri Blanco, Ardisia pyramidalis (Cav.) Pers, Meliaceae, Myrsinaceae, teratogenicity, hypervitaminosis A, reproductive performance, embryo morphology.

Remodeling of fetoplacental arteries in rats due to chronic hypoxia

The increased fetoplacental vascular resistance due to chronic hypoxia cannot be explained by simple hypoxic vasoconstriction, as it sustains to some degree after recovery in normobaric environment. To verify a hypothesis that fetoplacental arteries undergo remodeling of their walls similar to remodeling of pulmonary arteries in hypoxic pulmonary hypertension, we used a model of the chronically hypoxic rat placenta. Han Wistar pregnant rats were exposed to 14-day hypoxia (10% of oxygen) during the 6th to 19th day of pregnancy. Chronic hypoxia elicited in both intraplacental (prelabyrinthine) and chorionic plate (insertion) arteries significant narrowing of their lumina. Irregular thickening of their adventitia due to an increase in collagen fibers as well as ground substance was observed; reticular fibers were fragmented. Because of remodeling of fetoplacental arteries, a model of chronically hypoxic rat placenta could simulate human preplacental hypoxia and consequent effects.

Evaluation of vertical transmission of Toxoplasma gondii in Calomys callosus model after reinfection with heterologous and virulent strain

Toxoplasma gondii is an obligate intracellular protozoan parasite that causes a variety of clinical syndromes, but the infection is severe in immunocompromised individuals and during pregnancy due to the possibility of transplacental transmission of the parasite causing congenital toxoplasmosis. Vertical transmission of the parasite usually occurs when females are primarily infected during pregnancy. Calomys callosus is resistant to T. gondii ME49 strain, which presents a moderate virulence and congenital disease occurs only during the acute phase of infection. The aim of this study was to determine whether vertical transmission occurs when females of C. callosus chronically infected with ME49 strain of T. gondii are reinfected with a highly virulent strain (RH, type I). Females were infected with cysts of the ME49 strain. On the 1st day of pregnancy, animals were reinfected with tachyzoites of the RH strain. In the 19th day of pregnancy, placentas and embryos were processed for morphological analysis, immunohistochemistry and for detection of the parasite by PCR and mouse bioassay. Morphological and immunohistochemical analyses revealed the presence of parasites only in placental tissues. Mouse bioassay results showed seroconversion only in mice that were inoculated with placental tissues. Also, T. gondii DNA was detected only in placental samples. Congenital toxoplasmosis does not occur in C. callosus females chronically infected with the moderately virulent ME49 strain of T. gondii and reinfected with the highly virulent RH strain, thus indicating that primary T. gondii infection before pregnancy leads to an effective long-term immunity preventing transplacental transmission to the fetus.

MKP-1 mediates glucocorticoid-induced ERK1/2 dephosphorylation and reduction in pancreatic β-cell proliferation in islets from early lactating mothers

Maternal pancreatic islets undergo a robust increase of mass and proliferation during pregnancy, which allows a compensation of gestational insulin resistance. Studies have described that this adaptation switches to a low proliferative status after the delivery. The mechanisms underlying this reversal are unknown, but the action of glucocorticoids (GCs) is believed to play an important role because GCs counteract the pregnancy-like effects of PRL on isolated pancreatic islets maintained in cell culture. Here, we demonstrate that ERK1/2 phosphorylation (phospho-ERK1/2) is increased in maternal rat islets isolated on the 19th day of pregnancy. Phospho-ERK1/2 status on the 3rd day after delivery (L3) rapidly turns to values lower than that found in virgin control rats (CTL). MKP-1, a protein phosphatase able to dephosphorylate ERK1/2, is increased in islets from L3 rats. Chromatin immunoprecipitation assay revealed that binding of glucocorticoid receptor (GR) to MKP-1 promoter is also increased in islets from L3 rats. In addition, dexamethasone (DEX) reduced phospho-ERK1/2 and increased MKP-1 expression in RINm5F and MIN-6 cells. Inhibition of transduction with cycloheximide and inhibition of phosphatases with orthovanadate efficiently blocked DEX-induced downregulation of phospho-ERK1/2. In addition, specific knockdown of MKP-1 with siRNA suppressed the downregulation of phospho-ERK1/2 and the reduction of proliferation induced by DEX. Altogether, our results indicate that downregulation of phospho-ERK1/2 is associated with reduction in proliferation found in islets of early lactating mothers. This mechanism is probably mediated by GC-induced MKP-1 expression.

Influence of intracerebral infections with Streptococcus pneumoniae and Escherichia coli on the course of experimental Alzheimer’s dementia

Stressor presence during the last weeks of gestation has been associated with behavioral disorders in later life. In this study we support further research on the long term effects of prenatal stress on Swiss mice descendant's behavior. Prenatal stress procedure consisted on restraining the dams under bright light for 45 min, three times per day from the 15th day of pregnancy, until birth. After weaning, offspring's motor performance and spontaneous exploratory behavior were measured by the tight-rope and T-maze tests, respectively. We also evaluated anxiety behavior using elevated plus maze test. We found that maternal stress improves the performance of the animals in the tight rope test and that this effect was sex and age dependent: prenatal stressed males obtained the best scores during the first month of life, while in females the same was achieved at the second month. Spontaneous exploratory behavior analysis revealed that it was elevated in prenatal stressed males and that this effect persisted on time. However, we did not find significant differences on this behavioral response among both females groups. Finally, differences on anxiety behavior were found only in females: prenatally stressed animals showed a higher proportion of entries into the open arms of a plus maze (reduced anxiety) compared to the control group. Our results show that prenatal stress modifies the normal behavior of the progeny: prenatal stressed animals have a better performance in the carried out test. These notably results suggest the existence of an adaptive response to prenatal stress.

Changes in Liver Gene Expression of Azin1 Knock-out Mice

The ornithine decarboxylase antizyme inhibitor (AZI) was discovered as a protein that binds to the regulatory protein antizyme and inhibits the ability of antizyme to interact with the enzyme ornithine decarboxylase (ODC). Several studies showed that the AZI protein is important for cell growth in vitro. However, the function of this gene in vivo remained unclear. In our study, we analyzed the transcriptional profiles of livers on the 19th day of pregnancy of Azin1 knock-out mice and wild-type mice using the Agilent oligonucleotide array. Compared to the wild-type mice, in the liver of Azin1 knock-out mice 1812 upregulated genes (fold change > or = 2) and 1466 downregulated genes (fold change < or = 0.5) were showed in the microarray data. Altered genes were then assigned to functional categories and mapped to signaling pathways. These genes have functions such as regulation of the metabolism, transcription and translation, polyamine biosynthesis, embryonic morphogenesis, regulation of cell cycle and proliferation signal transduction cascades, immune response and apoptosis. Real-time PCR was used to confirm the differential expression of some selected genes. Overall, our study provides novel understanding of the biological functions of AZI in vivo.

Interaction among peroxisome proliferators-activated receptor alpha, cytochrome P450 oxysterol 7α-hydroxylase and estrogen receptor and its association with intrahepatic cholestasis in pregnant rats

To investigate the relationship between interaction of peroxisome proliferators-activated receptor alpha (PPARα), cytochrome P450 oxysterol 7α-hydroxylase (CYP7B1) and estrogen receptor (ER) and intrahepatic cholestasis in pregnant rats. Eighty clean SD pregnant rats were selected and divided into four groups randomly with 20 in each. Since the 13th day of pregnancy, rats in the control group was injected subcutaneously with refined vegetable oil 2.0 ml×kg(-1)×d(-1), those in the low-dose, moderate-dose and high-dose groups received 17-α-ethynylestradiol (EE) 1.0 mg×kg(-1)×d(-1), 1.25 mg×kg(-1)×d(-1) and 1.5 mg×kg(-1)×d(-1), respectively. All rats were sacrificed at the 21(st) day of pregnancy and maternal hepatic tissues were collected. The serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), total bile acid (TBA) and bilirubin (BIL) were determined by enzyme linked immunosorbent assay (ELISA). The mRNA expressions of PPARα, CYP7B1, ERα and ERβ in maternal rat livers were examined by real-time PCR. (1) Biochemical indicators: the serum levels of ALT, AST, TBA and BIL were significantly lower in the control group than in the rest 3 groups, respectively [control group: (41.1 ± 2.8) U/L, (44.4 ± 3.6) U/L, (26.4 ± 5.6) µmol/L and (2.8 ± 0.2) U/L; low-dose group: (48.2 ± 3.4) U/L, (47.9 ± 3.7) U/L, (36.4 ± 4.2) µmol/L and (4.2 ± 0.2) U/L; moderate-dose group: (70.4 ± 5.3) U/L, (68.4 ± 5.6) U/L, (64.3 ± 3.8) µmol/L and (6.2 ± 1.2) U/L; high-dose group: (72.4 ± 7.6) U/L, (70.2 ± 3.8) U/L, (72.4 ± 7.8) µmol/L and (8.2 ± 2.2) U/L, P < 0.05], and those in the moderate or high-dose groups were higher than in the low-dose group (P < 0.05). (2) mRNA expression of ERα and ERβ: the mRNA expression of ERα in pregnant rat livers increased in a dose-dependent manner, which were all significantly higher than that in the control group, respectively (low-dose group: 0.76 ± 0.02); moderate-dose group: (0.99 ± 0.04; high-dose group: 1.21 ± 0.01; control group: 0.65 ± 0.01, P < 0.05), but no difference was found among the 4 groups in the mRNA expression of ERβ (P > 0.05). (3) mRNA expression of CYP7B1 and PPARα: the mRNA expression of CYP7B1 in pregnant rat livers increased from the low-dose group to the high-dose group, and were all higher than that of the control group (low-dose group: 0.93 ± 0.01; moderate-dose group: 0.99 ± 0.06; high-dose group: 1.22 ± 0.04; control group: 0.75 ± 0.02, P < 0.05). However, the mRNA expression of PPARα decreased from the low-dose group to the high-dose group, and were all lower than that of the control group (low-dose group: 0.83 ± 0.05; moderate-dose group: 0.71 ± 0.02; high-dose group: 0.64 ± 0.03; control group: 1.35 ± 0.05; P < 0.05). The down regulated mRNA expression of PPARα, caused by higher dose of estrogen, may increase the expression of CYP7B1 due to the ineffectiveness of the inhibition of PPARα on CYP7B1, which may further stimulate the ERα activity and then induce intrahepatic cholestasis. Abnormal expression of PPARα, CYP7B1 and ER may play a role in the pathogenesis of estrogen-induced intrahepatic cholestasis.

Effects of Ginkgo biloba extract on the embryo‐fetal development in Wistar rats

Ginkgo biloba extract (GBE) is an herbal medicine used for treating neurodegenerative diseases, cerebrovascular insufficiency, peripheral arterial occlusive disease, and also vestibular disturbance. Some components of GBE have presented estrogenic effects and, in a previous study, high dosages of GBE caused intra-uterine growth retardation in fetuses of Wistar rats treated during the fetogenesis period. Pregnant Wistar rats were treated, through gavage, with different dosages of aqueous GBE (3.5, 7.0, and 14.0 mg/Kg/day), during the tubal transit and implantation period. Rats were killed on the 15th day of pregnancy and the following parameters were evaluated: clinical symptoms of maternal toxicity; maternal body weight; feed and water intake; maternal liver, kidney, and ovary weights; number of corpora lutea; implants per group ratio; pre- and post-implantation loss per group ratio; live fetuses mean; dead fetuses percentage; fetus and placenta weight per offspring ratio; and fetal external malformation. No significant alteration was found for both the maternal and embryonic parameters evaluated. The GBE treatment in pregnant Wistar rats, during the tubal transit and implantation period, caused no toxic effect on the maternal organism and did not induce embryonic death, growth retardation, and/or fetal malformations.

Maternal tamoxifen treatment alters oocyte differentiation in the neonatal mice: Inhibition of oocyte development and decreased folliculogenesis

Primary germ cells after migration to the developing ovary differentiate to oogonia and oocytes. The formation and number of primordial follicles in early fetal life are determining factors in the fertility state of adult life. Tamoxifen is used both to stimulate ovulation and as an anticancer drug. The aim of the present study was to evaluate the effect of tamoxifen on oocyte and follicular development and differentiation in mice. Thirty adult female and 15 adult male mice were used in the present study. The female mice were divided into two groups: control and experimental. Two female mice at their sterous cycle were placed with one male mouse in a cage for mating. The observation of a vaginal plug was considered the 1st day of pregnancy. On the 13th day of pregnancy the mice received 100 microg tamoxifen by i.p. injection. At the end of pregnancy 2-, 3-, 6- and 7-day-old newborns were killed and their ovaries were fixed and prepared for light and electron microscopic studies. The number of follicular nests and diameter of primordial and primary follicles were determined using Motic software (Motic Incorporation Ltd, Canada) and compared with control values using t-test. Microscopy and morphometry showed that oocyte nests are formed on the 2nd and 3rd days and follicles are distinguished on the 6th and 7th days. Morphometric studies revealed that the number and diameters of oocyte nests were significantly (P < 0.001) reduced in the experimental groups compared to the control group. However, the numbers and diameters of primordial and primary follicles in experiential and controls were not significantly different. Electron microscopic studies revealed that in the control group, oocytes were separated from each other and were at primordial follicle stage. However, in the experimental group, the oocytes were in clusters as oocyte nests. The results indicate that tamoxifen suppresses follicular differentiation at early stages but does not affect the development of already differentiated follicles.

Inhibitory avoidance acquisition in adult rats exposed to a combination of ethanol and methylmercury during central nervous system development

Previous studies have shown that combined exposure to ethanol (EtOH) and methylmercury (MeHg) in rats during central nervous system development produces several behavioural impairments. This present study was done to investigate inhibitory avoidance acquisition and panic-like disorders in rats in an elevated T-maze (ETM) model of anxiety. Pregnant rats received tap water or EtOH at 22.5% (w/v) (6.5 g/kg per day, by gavage) during pregnancy and lactation. On the 15th day of pregnancy, half of each group received MeHg (8 mg/kg, by gavage). Adult offspring intoxicated by both EtOH + MeHg showed an increase in the ETM re-exposure time. Upon analysis of the enclosed arms latency in baseline and avoidance 1 session it was observed that the rats spent less time inside the arm, suggesting impairment in their short-term memory. The escape latency decreased for EtOH + MeHg and also for EtOH and MeHg groups, suggesting panic-like behaviour. After 24-h and 7-day trials (tests and retests), MeHg and EtOH + MeHg groups had their latency in the enclosed arm reduced with the exception of the EtOH group, revealing memory impairment. Upon analysis of the risk assessment, animals treated with EtOH + MeHg were the only ones to show a decrease in all evaluation stages. This study demonstrates that the exposure to both EtOH and MeHg has an impact on memory and panic-related behaviours, leading to the assertion that this association of toxicants should be studied more in detail to clarify the precise mechanisms of these pharmacological effects.

Mechanism of the decreased food consumption and weight gain in rats following consumption of aqueous extract of the calyx of Hibiscus sabdariffa during pregnancy

Objective To investigate the possible mechanisms of the decreasing fluid and food consumption following Hibiscus sabdariffa (HS) consumption. Methods On the 1st day of pregnancy, rats were randomly divided into three groups with six animals per each group. One group was given tap water, one was given with extract at 0.6 g/100 mL while the third group was given with extract at 1.8 g/100 mL as their drinking solution. All groups received normal rat chow and drinking solution ad libitum. Fluid& food intake and weight were measured daily throughout pregnancy and Na + concentration in plasma was determined on the 18th day of pregnancy. Results Results showed decreased fluid and food consumption, decreased weight gain and increased sodium ion concentration in plasma of rats with HS extract compared with the control group. Conclusions Consumption of aqueous extract of the calyx of HS during pregnancy decreases food consumption and weight gain through mechanisms that may depend on Na + in HS content and elevating Na + concentration.

Fluoride-induced brain damages in suckling mice

In order to reveal mechanisms of brain damages resulted from fluoride toxicity, we treated adult female mice of Swiss Albinos strain by 500 ppm NaF (226 ppm F −) in their drinking water from the 15th day of pregnancy until the day 14 after delivery. All mice were sacrificed on day 14 after parturition. During treatment, levels of thiobarbituric acid reactive substances (TBARS), the marker of lipid peroxidation extend, increased, while the activities of the antioxidant enzymes such as glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT), and the level of glutathione (tGSH) decreased significantly in both cerebellum and cerebrum compared with those of the control group. These results suggested that fluoride enhanced oxidative stress in the brain, thereby disturbing the antioxidant defense of nursing pups. In addition, acetylcholinesterase (AChE) activity in both cerebellum and cerebrum was inhibited after treatment with fluoride. In our previous studies we have found, a decrease in plasma thyroid hormone levels of nursing pups whose mothers were treated by NaF. In cerebellum of mice, migration of neurons from the external granular layer to the internal granular layer occurred postnatally and was dependent upon the presence of thyroid hormone. In hypothyroidism, several neurons failed to complete their migration and died. Key guidance signals to these migrating neurons were provided by laminin, an extracellular matrix protein fixed to the surface of astrocytes. In the present study we examined the expression and distribution of laminin in cerebellum of 14-day-old mice. Immunoreactive laminin was disappeared by postnatal day 14 in cerebellum parenchyma of control pups and was restricted to vasculature despite the continued presence of granular cells in the external granular layer. In contrast, in cerebellum of NaF treated pups, laminin was deposited in organised punctuate clusters in the molecular layer. These data indicated that the disruption of laminin distribution might play a major role in the profound derangement of neuronal migration observed in cerebellum of NaF treated pups.

Prenatal action of lead acetate on the antioxidant glutathione system of the brain of newborn rats in vivo and on neurite growth in vitro

We studied the state of the antioxidant glutathione system (activity of glutathione peroxidase, glutathione reductase, and content of GSH and GSSG) and the level of lipid peroxidation in the brain of newborn rats, as well as the intensity of neurite growth in the cultured spinal ganglia of these animals after prenatal treatment with lead acetate. Daily addition (6 mg/kg) or single addition on the 18th day of pregnancy (200 mg/kg) of lead acetate to food of pregnant females resulted in a considerable decrease in the activity of the glutathione system and increase in the levels of GSSG and malonic dialdehyde in the brain tissue. The lead intoxication also inhibited neurite growth in cultured ganglia. In addition, the permanent presence of lead acetate (0.02 mM) in the cultures of ganglia of intact rats on the second and third days in vitro also led to inhibition of neurite growth. The data obtained indicate that oxidative stress, which results in decreased antioxidant activity, may be one of the main mechanisms that underlie toxic injury of central and peripheral neurons after prenatal action of lead.

Steroid hormones and prolactin in porcine follicular fluid in estrous cycle and early pregnancy.

Concentrations of progesterone (P4), estradiol 17-beta (E2), testosterone (T) and prolactin (PRL) were estimated by RIA in porcine follicular fluid (FF) on 5th, 8th, 13th, 17th and 20th day of the estrous cycle and on 18th and 28th day of pregnancy. The highest P4 and E2 concentrations were found on 20th day of the estrous cycle. The P4 level measured on that day differed (P less than 0.05) from the levels on 5th, 13th and 17th day and E2 level on 20th day was different from the levels on remaining days of the estrous cycle, i.e. 5th, 8th, 13th and 17th. In pregnancy, concentrations of these steroids were much lower (P less than 0.05) compared to 20th day of the estrous cycle. No differences were found in T levels neither in estrous cycle nor in pregnancy. PRL concentration was at the lowest level on 5th day of the estrous cycle and it was different (P less than 0.05) from the concentrations on 8th day of the cycle and on 18th day of pregnancy (P less than 0.05). PRL content found on 28th day of pregnancy was lower (P less than 0.05) than on 18th day.

THE ACUTE-PHASE PROTEIN α2-MACROGLOBULIN PLAYS AN IMPORTANT ROLE IN RADIOPROTECTION IN THE RAT

The importance of alpha2-macroglobulin (alpha2M) in natural radioprotection was studied by examining its radioprotective effectiveness in rat models of exogenously and endogenously, preexposure-increased alpha2M. Radioprotective efficacy was ascertained by the postirradiation survival rate, the restoration of body weight, and the leukocyte count, which were monitored during a 4-week follow-up period. The results were compared with the effects of a pretreatment with the synthetic radioprotective agent amifostine (Ami), which provides 100% protection in rats whole-body-irradiated by x-rays given in a dose of 6.7 Gy (LD50/30). Raising the plasma concentration of alpha2M 15-fold in male rats by a single intraperitoneal injection of purified protein provided 100% survival of irradiated animals. Female rats on the 19th day of pregnancy with endogenously elevated levels of alpha2M displayed improved survival (80%) compared with untreated rats (50% survival). After alpha2M administration, the pregnant, irradiated rats exhibited 100% survival. In both males and pregnant females, alpha2M administration promoted body weight and leukocyte postirradiation recovery as in Ami-pretreated rats. These findings, together with our observation that Ami administration induced a 45-fold increase in alpha2M in the circulation, led us to conclude that alpha2M has an essential role in both natural and amifostine-mediated radioprotection in the rat.

Changes of agouti-related protein in hypothalamus, placenta, and serum during pregnancy in the rat

Agouti-related protein (AGRP) is a homolog of the agouti protein and acts as an antagonist of peptides derived from propiomelanocortin through melanocortin receptors. This peptide is produced mainly in the hypothalamus, particularly during negative energy balance and influences increased food intake. In the hypothalamus, this peptide is co-expressed in arcuate nuclei with neuropeptide Y, another important peptide that regulates energy metabolisms. In our study, we analyzed changes in the Agrp mRNA level in the hypothalamus as well as mRNA and protein levels in placenta during different stages of rat pregnancy. We also investigated the AGRP level in the blood serum. In this study, we found the AGRP level in serum increased, while its gene expression in the hypothalamus increased only up to the 13th day of pregnancy, and decreased on the 18th day. This study demonstrates that AGRP is expressed during late pregnancy in placenta. Moreover, we found that AGRP expression is higher on the 18th than on the 13th day of pregnancy. Our results indicate that AGRP may play an important role during pregnancy in the mother's and, possibly, also in the fetus's energy balance.

Gestational stress delays maturation of the hypoxic ventilatory response: an in vivo and in vitro study

Exposure to stress during gestation disrupts CNS development; however, its effects on the respiratory control system are unknown. We tested the hypothesis that exposing dams to a predator odor during gestation disrupts the maturation of the hypoxic ventilatory response (HVR) of newborn rats. From the 9th to the 19th day of pregnancy, females subjected to gestational stress (GS) were placed in a cage containing 35 μl of TMT, a component of fox odor for 20 min. For sham treatment, gestating females were exposed to a strong odor (butyric acid, 105 μl). Controls were undisturbed. Ventilatory activity was measured at post natal days 0, 2 and 4 using plethysmography (in vivo) and "en bloc" brainstem spinal cord preparations (in vitro). Measurements were performed under baseline conditions and hypoxia. In vivo: unlike controls, P4 male pups born to GS dams could not sustain a significant increase in breathing frequency through out the hypoxic period (12% O2, 20 min). This effect of GS was not observed in females. In vitro: at the end of hypoxia (7% O2, 20 min), preparations from GS pups showed a smaller phrenic burst frequency decrease than controls (‐58% vs ‐76%). No sexual dimorphism was observed in vitro. GS delays maturation of the hypoxic ventilatory response. Comparison of in vivo vs in vitro data suggests that GS affects peripheral chemoreceptor development and/or integration of afferent signal in the CNS. Supported by the CIHR.

The effects of transient systemic hypotension on renal oxidative status, morphology and plasma nitric oxide levels in pregnant rats

Objective. Transient hypotension attacks, frequently experienced during pregnancy, have detrimental effects on maternal and fetal physiology. Despite the strong autoregulatory mechanisms, kidneys are remarkably sensitive to hypoperfusion. Transient hypotension together with high metabolic demand and increased oxygen requirement during pregnancy may disturb the oxidant status and natural course of nitric oxide (NO) metabolism. Therefore, we investigated in this study the effects of systemic hypotension during pregnancy on kidney oxidant status and morphology and plasma NO levels in an experimental hypotension model in rats.Methods. Twenty-four rats were allocated into four groups as non-pregnant control (NPC), non-pregnant hypotensive (NPH), pregnant control (PC) and pregnant-hypotensive (PH). Blood pressure was monitored only (NPC, PC) or systemic hypotension by blood withdrawal (NPH, PH) was produced for 30 min following catheterisation on the 15th day of pregnancy or at a corresponding time in the control animals. Animals were sacrificed after 48 h of reperfusion. Malonyldialdehyde (MDA) and reduced glutathione (GSH) levels, superoxide dismutase and catalase activities in the kidneys and plasma NO levels were measured. Tissues were evaluated, histologically.Results. Hypotension and/or pregnancy elevated MDA levels, which was significant in the NPH and PH groups (p < 0.05). GSH levels were lower in all groups compared with the NPC group (p < 0.05). Pregnancy itself increased NO only in the control animals (p < 0.05), not in the hypotensive pregnant rats. Transient hypotension resulted in kidney damage in both hypotension groups, and damage was more prominent in renal cortical regions. The most severe effects were seen in the PH group (p < 0.05).Conclusions. The findings of this study show that transient hypotension induces a kidney injury in pregnant rats. MDA and GSH in kidneys seem to play a role in the pathophysiology of this injury. However, the roles of antioxidant enzymes and NO and the other underlying mechanisms deserve and necessitate further investigation regarding the long-term health of the mother and fetus.