Newborn Rat Pups Research Articles

GM1 Ameliorates Lead-Induced Cognitive Deficits and Brain Damage Through Activating the SIRT1/CREB/BDNF Pathway in the Developing Male Rat Hippocampus.

Developmental lead (Pb) exposure involves various serious consequences, especially leading to neurotoxicity. In this study, we examined the possible role of monosialoganglioside (GM1) in lead-induced nervous impairment in the developing rat. Newborn male Sprague-Dawley rat pups were exposed to lead from birth for 30days and then subjected to GM1 administration (0.4, 2, or 10mg/kg; i.p.) or 0.9% saline. The results showed that developmental lead exposure significantly impaired spatial learning and memory in the Morris water maze test, reduced GM1 content, induced oxidative stress, and weakened the antioxidative systems in the hippocampus. However, co-treatment with GM1 reversed these effects. Moreover, GM1 counteracted lead-induced apoptosis by decreasing the expression of Bax, cleaved caspase-3, and by increasing the level of Bcl-2 in a dose-dependent manner. Furthermore, we found that GM1 upregulated the expression of SIRT1, CREB phosphorylation, and BDNF, which underlie learning and memory in the lead-treated developing rat hippocampus. In conclusion, our study demonstrated that GM1 exerts a protective effect on lead-induced cognitive deficits via antioxidant activity, preventing apoptosis, and activating SIRT1/CREB/BDNF in the developing rat hippocampus, implying a novel potential assistant therapy for lead poisoning.

Hypothermia broadens the therapeutic time window of mesenchymal stem cell transplantation for severe neonatal hypoxic ischemic encephalopathy

Recently, we have demonstrated that concurrent hypothermia and mesenchymal stem cells (MSCs) transplantation synergistically improved severe neonatal hypoxic ischemic encephalopathy (HIE). The current study was designed to determine whether hypothermia could extend the therapeutic time window of MSC transplantation for severe neonatal HIE. To induce HIE, newborn rat pups were exposed to 8% oxygen for 2 h following unilateral carotid artery ligation on postnatal day (P) 7. After approving severe HIE involving >50% of the ipsilateral hemisphere volume, hypothermia (32 °C) for 2 days was started. MSCs were transplanted 2 days after HIE modeling. Follow-up brain MRI, sensorimotor function tests, assessment of inflammatory cytokines in the cerebrospinal fluid (CSF), and histological evaluation of peri-infarction area were performed. HIE induced progressively increasing brain infarction area over time, increased cell death, reactive gliosis and brain inflammation, and impaired sensorimotor function. All these damages observed in severe HIE showed better, robust improvement with a combination treatment of hypothermia and delayed MSC transplantation than with either stand-alone therapy. Hypothermia itself did not significantly reduce brain injury, but broadened the therapeutic time window of MSC transplantation for severe newborn HIE.

Factors Known to Influence the Development of Necrotizing Enterocolitis to Modify Expression and Activity of Intestinal Alkaline Phosphatase in a Newborn Neonatal Rat Model.

Prematurity, formula feeding, and early weaning strongly influence enterocyte differentiation. Intestinal alkaline phosphatase (IAP), an endogenous protein expressed in the intestines, is one enzyme that is affected by these factors. IAP supplementation decreases the severity of necrotizing enterocolitis (NEC) injury. We, therefore, hypothesized that prematurity predisposes this population to NEC due to IAP deficiency and investigated IAP expression and function in a neonatal rat model. Pre- and full-term newborn Sprague-Dawley rat pups were sacrificed on consecutive days of life both after vaginal or cesarean birth and following either breast or formula feeding. Compared with controls, cesarean delivery and formula feeding are associated with lower levels of IAP. The formula-fed pups continued to have low baseline IAP activity. Neither prematurity nor formula feeding led to differences of intestinal injury. Prematurity and formula feeding are associated with inhibition of IAP expression and activity. Both may increase the risk of NEC and early enteral supplementation of IAP to newborns at risk of NEC may be of therapeutic benefit.

Leptin Stabilizes Breathing but does not affect CO2 Chemosensitivity in Newborn Rat Pups

Premature infants have periodic breathing (PB) and chronic intermittent hypoxia (CIH) that increases during the 2nd week of life. Leptin (LEP) is a hormone produced by adipocytes and increases central CO2 chemoreceptors sensitivity. LEP is also produced by the placenta, and in newborn infants LEP levels are highest at birth and then rapidly fall. We hypothesis that the fall in LEP after birth is associated with the increase frequency of PB and apnea leading to CIH during the 2nd week of life in premature infants.ObjectiveTo determine the effect of exogenous LEP on breathing stability and CO2 sensitivity during the first week of postnatal life, using whole body flow‐through plethysmograph in freely behaving newborn rats.MethodsSprague Dawley (SD) rat pups remained with the nursing dam until the time of the experiment. On postnatal day (PD) 7, rat pups were injected intraperitoneally with either vehicle (saline/n=5), LEP6 (6 μg/gr/n=4) and LEP9 (9 μg/gr/n=5). After injection the pup was returned to nursing dam and litter mates for 30 mins followed by 30 mins in the plethysmograph prior to recording. Respiratory tracings were captured using PowerLab 8 data acquisition system (ADInstruments) and analyzed using LabChart. Ventilatory parameters; frequency, VT and Ve were compared during 21% O2, 40% O2/0% CO2, 40%O2/5%CO2 and return to 40%O2/0%CO2, and the coefficient of variation (CV) for Ve was calculated for each condition in the 3 treatment groups (SAL, LEP6, LEP9).ResultsSimilar to Stunden et al. in rat pups at PD 7–8 (Stunden et al,, Respir Physiol, 2001), frequency, VT and Ve did not significantly changed in response to hypercapnia (P=0.511), and LEP6 or LEP9 did not alter this response. However, LEP exposure did stabilize breathing with a reduction in the CV during 21%O2, 40%O2/0%CO2 and 40%O2/5%CO2 (Figure 1).ConclusionOur preliminary findings are consistent with that of Stunden et al, who reported no change in Ve in response to hypercapnia at PD 6–8 in SD rats. At this age, the hypothalamus is insensitive to the effect of leptin on feeding and metabolism (MacKay H et al., Mol Metab. 2014). Here we show that leptin does not induce nor augment CO2 chemosensitivity in newborn rats at PD7, but does at PD 18 (Gauda et al, unpublished data), and adults (Isono S et al., Anesthesiology, 2009). However our data does show that leptin stabilizes breathing during the first week of life in newborn rat pups. We speculate that unstable breathing that occurs in premature infants may be associated with the precipitous fall in leptin levels after birth.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

T-2 Mycotoxin Treatment of Newborn Rat Pups does not Significantly Affect Nervous System Functions in Adulthood

T-2 toxin is primarily produced by Fusarium sp. abundant under temperate climatic conditions. Its main harmful effect is the inhibition of protein synthesis. Causing oxidative stress, it also promotes lipid peroxidation and changes plasma membrane phospholipid composition; this may lead to nervous system alterations. The aim of the present study was to examine whether a single dose of T-2 toxin administered at newborn age has any long-lasting effects on nervous system functions. Rat pups were treated on the frst postnatal day with a single intraperitoneal dose of T-2 toxin (0.2 mg/bwkg). Body weight of treated pups was lower during the second and third week of life, compared to littermates; later, weight gain was recovered. At young adulthood, behavior was tested in the open feld, and no difference was observed between treated and control rats. Field potential recordings from somatosensory cortex and hippocampus slices did not reveal any signifcant difference in neuronal network functions. In case of neocortical feld EPSP, the shape was slightly different in treated pups. Long-term synaptic plasticity was also comparable in both groups. Seizure susceptibility of the slices was not different, either. In conclusion, T-2 toxin did not signifcantly affect basic nervous system functions at this dose.

Lead Affects Vitamin D Metabolism in Rats.

A negative association between blood lead and vitamin D concentrations has been reported, however, experimental data on the effect of lead (Pb) on vitamin D metabolism is scarce. We investigated the effects of Pb on serum vitamin D metabolites, vitamin D activating enzymes and vitamin D receptor (VDR) in rats. Newborn Wistar rat pups were exposed to 0.2% Pb-acetate via their dams’ drinking water from post-natal day (PND) 1 to 21 and directly in drinking water until PND30. Serum 25-hydroxyvitamin D was analyzed with LC-MS/MS and 1,25-dihydroxyvitamin D with an immunoassay. Tissue expression of vitamin D activating enzymes and VDR were measured by Western blot and immunohistochemistry. Serum 25-hydroxyvitamin D was significantly decreased at both PND21 and PND30, whereas 1,25-dihydroxyvitamin D was decreased (p < 0.05) only at PND21 in the Pb-exposed rats. Expression of renal 1-α-hydroxylase was decreased by Pb only at PND21 (p < 0.05) but the brain 1-α-hydroxylase was not affected. Hepatic 25-hydroxylase expression was significantly decreased at PND21 but significantly increased at PND30 by Pb exposure. VDR expression in the brain was increased at both PND21 and PND30 (p < 0.05). These results suggest that Pb interferes with vitamin D metabolism by affecting the expression of its metabolizing enzymes.

The role of oxidative stress in acute renal injury of newborn rats exposed to hypoxia and endotoxin.

Neonatal kidney injury is a frequent pathology, especially among premature infants. The search for effective nephroprotection requires the creation of adequate experimental models of nephropathy in newborns. In this study, we explored the development of acute kidney injury (AKI) in neonatal rats during hypoxia or administration of endotoxin. We found that 2-h hypoxia (8% O2 ) and the intraperitoneal injection of 4 mg·kg-1 lipopolysaccharide (LPS) causes the appearance of AKI markers, such as kidney injury molecule-1 (КIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in the rat urine after 24 and 72 h of exposure. On the other hand, the levels of blood urine nitrogen under the same conditions rise only slightly. The damaging effects of hypoxia and endotoxin were accompanied by histological changes in the renal tissue and a significant decrease in the proliferation marker, (proliferating cell nuclear antigen). It is revealed that 3 h after the introduction of LPS, levels of reactive oxygen species in the kidney were significantly increased, and the injection of the antioxidant N-acetylcysteine afforded protection from AKI, evaluated by urine КIM-1 and NGAL levels. Thus, the simulation of AKI in newborn rat pups can be employed in screening for potential nephroprotective drugs, particularly among antioxidative compounds to be used in neonatology.

Resistance to action potential depression of a rat axon terminal in vivo

The shape of the presynaptic action potential (AP) has a strong impact on neurotransmitter release. Because of the small size of most terminals in the central nervous system, little is known about the regulation of their AP shape during natural firing patterns in vivo. The calyx of Held is a giant axosomatic terminal in the auditory brainstem, whose biophysical properties have been well studied in slices. Here, we made whole-cell recordings from calyceal terminals in newborn rat pups. The calyx showed a characteristic burst firing pattern, which has previously been shown to originate from the cochlea. Surprisingly, even for frequencies over 200 Hz, the AP showed little or no depression. Current injections showed that the rate of rise of the AP depended strongly on its onset potential, and that the membrane potential after the AP (Vafter) was close to the value at which no depression would occur during high-frequency activity. Immunolabeling revealed that Nav1.6 is already present at the calyx shortly after its formation, which was in line with the fast recovery from AP depression that we observed in slice recordings. Our findings thus indicate that fast recovery from depression and an inter-AP membrane potential that minimizes changes on the next AP in vivo, together enable high timing precision of the calyx of Held already shortly after its formation.

Z-cells and oogonia/oocytes in the advanced process of autophagy are the dominant altered cells in the ovaries of hypothyroid newborn rats

AbstractInduced prenatal hypothyroidism in rat pups leads to accelerated primordial follicle assembly and premature follicular atresia with ovary failure. This work investigates the influence of maternal hypothyroidism induced with 6-n-propyl-2-thyouracil (PTU) on the number and morphology of oogonia/oocytes in newborn rat pups with light and transmission electron microscopy. Expression of apoptosis and autophagy markers in oogonia/oocytes were examined using immunohistochemistry. Hypothyroid newborn pups had a decreased number of mitotic and resting oogonia, while the number of altered oogonia/oocytes was increased. Ultrastructural observations revealed the increased presence of degenerated pachytene oocytes (Z-cells) and oogonia/oocytes undergoing autophagy, apoptosis and combined apoptosis and autophagy, in this group. The most abundant altered oogonia/oocytes in the hypothyroid group were those with morphological features of advanced autophagy and Z-cells. The percentage of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) positive oogonia/oocytes was significantly lower in the hypothyroid group. No significant difference was recorded in the expression of caspase-3, ATG7 and LC3 possibly reflecting that these proteins were not involved in the oogonia/oocyte alteration process during prenatal rat hypothyroidism. The obtained results indicate that developmental hypothyroidism in the offspring enhances the number of Z-cells and oogonia/oocytes altered with the advanced process of autophagy.

Inhibition of Rac1 Signaling Downregulates Inflammasome Activation and Attenuates Lung Injury in Neonatal Rats Exposed to Hyperoxia

Background: Inflammatory injury, particularly the production of active interleukin (IL)-1β plays a major role in the pathogenesis of bronchopulmonary dysplasia (BPD) in preterm infants. The release of active IL-1β is controlled by posttranscriptional modifications of its proform (pro-IL-1β) through the inflammasome. Rac1 is a member of the Rho family of GTPases that regulate the inflammatory process. Objective: This study tested the hypothesis that Rac1 signaling increases inflammasome activation that results in damaging inflammation, and that the inhibition of Rac1 signaling prevents lung injury, by inhibiting inflammasome activation in a newborn rat model of BPD induced by hyperoxia. Methods: Newborn rat pups were exposed to room air or hyperoxia (85% O₂) and received daily intraperitoneal injections of placebo (normal saline) or NSC23766, a specific Rac1 inhibitor, for 10 days. The effects on lung inflammation, alveolarization, vascular development, vascular remodeling, right ventricular systolic pressure, and right ventricular hypertrophy (RVH) were then assessed. Results: Hyperoxia exposure upregulated Rac1 and increased the production of active IL-1β, which was accompanied by increasing expression of the inflammasome. In addition, hyperoxia induced the pathological hallmarks of BPD. However, treatment with NSC23766 significantly decreased inflammasome activation and macrophage infiltration, improved alveolar and vascular development, and reduced pulmonary vascular remodeling and RVH. Conclusion: These results indicate that Rac1 signaling regulates the expression of the inflammasome and plays a pivotal role in the pathogenesis of hyperoxia-induced neonatal lung injury. Therefore, targeting Rac1 signaling may provide a novel strategy to prevent and treat BPD in preterm infants.

The Effect of Congenital and Postnatal Hypothyroidism on Depression-Like Behaviors in Juvenile Rats.

Objective:The aim of this study was to investigate depression-like behaviors of juvenile rats with congenital and postnatal hypothyroidism.Methods:Twenty-seven newborn rat pups were used. First, 6-month-old Wistar Albino female rats were impregnated. Methimazole (0.025% wt/vol) was given to dam rats from the first day of pregnancy until postnatal 21 days (P21) to generate pups with congenital hypothyroidism (n=8), whereas in the postnatal hypothyroidism group (n=10), methimazole was given from P0 to P21. In the control group (n=9), dam rats were fed ad libitum and normal tap water. Offspring were fed with breast milk from their mothers. The behavioral parameters were measured with the juvenile forced swimming test (JFST). The procedure of JFST consisted of two sessions in two consecutive days: the 15-minute pre-test on day 1 and the 5-minute test on day 2.Results:Increased immobility and decreased climbing duration were observed in both congenital and postnatal hypothyroidism groups. Decreased swimming duration was detected in the postnatal hypothyroidism group. Both hypothyroidism groups had a lower body weight gain compared with the control group, while the congenital hypothyroidism group had the lowest body weight.Conclusion:Our results showed that hypothyroidism had negative effects on depression-like behavior as well as on growth and development. Both congenital and postnatal hypothyroidism caused an increase in immobility time in JFST. New studies are required to understand the differing results on depression-like behavior between congenital and postnatal hypothyroidism.

Administration of Huperzia quadrifariata Extract, a Cholinesterase Inhibitory Alkaloid Mixture, has Neuroprotective Effects in a Rat Model of Cerebral Hypoxia-Ischemia.

Neonatal hypoxia-ischemia (HI) is an etiologic component of several neurologic pathologies associated to cognitive impairment. The mechanisms involved in HI-induced tissue damage start immediately after HI and extend for days. Acetylcholine is an important neurotransmitter in the central nervous system and exerts a protector effect on tissue damage by modulating inflammation, and cholinesterase inhibitors have shown neuroprotective properties and their action are often attributed to inhibition of the immune response. The administration of Huperzia quadrifariata alkaloid extract (HqAE), with potent and selective cholinesterase inhibitor properties, will reduce the HI induced behavioral deficits and tissue damage. A total of 84 newborn Wistar rat pups at post natal day 7 (PND7) were subjected to right carotid occlusion followed by 1h of hypoxia (8% of O2) and i.p. injections of saline, vehicle or HqAE (10mg/kg). Morris Water Maze and inhibitory avoidance tests were used to assess the cognitive function. Flow cytometry was performed at PND11. Histological analysis was performed at PND45. HqAE treatment was able to prevent the HI induced cognitive deficits in both tests and, at PND45, histological analysis showed that HqAE treatment reduced hippocampus tissue damage. Flow cytometry of the injured hippocampus revealed that the treatment was able to reduce cellular death and the number of infiltrating T cells. Altogether, these results show the therapeutic potential of the Huperzia quadrifariata alkaloid extract to prevent cognitive deficits and histological damage caused by neonatal hypoxia-ischemia, probably by reducing cellular death and T cell mobilization.

Evaluation of apoptotic cell death on liver and kidney tissues following administration of levetiracetam during prenatal period

Objective: Levetiracetam is a new generation antiepileptic drug used in treatment of patients with epilepsy and has adverse effects on different tissues. We aimed to evaluate the apoptotic effects of levetiracetam exposure during pregnancy on liver and kidney tissues of rat pups.Methods: We analyzed the newborn rat pups exposed to levetiracetam during prenatal period. Fifteen pregnant female rats were divided into three groups. The group 1 and 2 rats were treated with different doses of levetiracetam (25 mg/kg/d and 50 mg/kg/d, respectively) from gestational days 1–22 during pregnancy. Group 3 (control group) was treated with the same volume of saline. Apoptosis was evaluated by the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) method. Liver and kidney tissues from rat pups were used for investigation.Results: The percent of TUNEL positive apoptotic cells in group 1 were 22 and 17.5 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 2 were 20.9 and 20.9 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 3 were 18.4 and 17.1, respectively, for kidney and liver. The apoptotic index was the same in kidney and liver tissues of all groups.Conclusion: Our results demonstrate that the prenatal exposure of levetiracetam has no apoptotic effects on liver and kidney of rat pups and, it has biosafety in pregnancy in terms of apoptosis. The first study evaluating the apoptotic effects on liver and kidney tissues following administration of levetiracetam during prenatal period.

Optimal Timing of Mesenchymal Stem Cell Therapy for Neonatal Intraventricular Hemorrhage.

We recently showed that intraventricular transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) significantly attenuated posthemorrhagic hydrocephalus (PHH) and brain injury after severe intraventricular hemorrhage (IVH) in newborn rat pups. The purpose of this study was to optimize the timing of MSC transplantation for severe IVH. Severe IVH was induced by injecting 100 µl of blood into each ventricle of Sprague-Dawley rats on postnatal day 4 (P4). Human UCB-derived MSCs (1 × 10(5) cells in 10 µl of normal saline) were transplanted intraventricularly under stereotaxic guidance either early at P6 or late at P11. Serial brain MRIs and behavioral function tests, such as negative geotaxis and rotarod tests, were performed. At P32, brain tissue samples were obtained for histological and biochemical analyses. Intracerebroventricular transplantation of MSCs significantly attenuated the development of PHH, behavioral impairment, increased apoptosis and astrogliosis, reduced corpus callosum thickness and brain myelination, and upregulated inflammatory cytokines including interleukin (IL)-1α, IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) at P6 but not at P11 after induction of severe IVH. Intracerebroventricular transplantation of human UCB-derived MSCs attenuated PHH and brain injury after severe IVH in newborn rats in a time-dependent manner. Significant neuroprotection was only demonstrated when administered early at 2 days after induction but not late at 7 days after induction of severe IVH.

Maternal dietary supplementation with omega-3 polyunsaturated fatty acids confers neuroprotection to the newborn against hypoxia-induced dopamine dysfunction

IntroductionUp to 84% of prematurely born infants suffer hypoxic, anoxic, and ischemic insults. Those infants with subsequent behavioral, motor or cognitive dysfunction represent 8–11% of all live births. Yet, no interventions employed during pregnancy attenuate risk of morbidity in those at-risk infants. Dietary supplementation with omega-3 polyunsaturated fatty acids (ω-3 PUFAs) has been shown to reduce stroke-induced neuropathology in rat models emulating this adverse clinical event. To extend those studies we sought to determine whether maternal dietary supplementation with ω-3 PUFAs would confer neuroprotection against hypoxia-induced neurochemical dysfunction in newborn rat pups exposed to repetitive hypoxic insults. MethodsWe provided pregnant rats with either a ω-3 PUFA enriched diet or else a standard rat chow diet. At postnatal day 7, pups were assigned randomly to either repetitive hypoxic insults or repetitive bursts of room air. On postnatal day 12, pups were sacrificed and brain dopamine levels characterized. ResultsBaseline brain dopamine levels did not differ between rat pups born to dams who received ω-3 PUFA enriched versus standard rat chow diets. Rat pups born to dams maintained on normal diets, who were exposed to five days of repetitive hypoxic insults, experienced a 57% reduction in striatal dopamine levels accompanied by significant apoptosis. In contrast, ω-3 PUFA-enriched newborn pups experienced no loss in striatal dopamine levels, and only minimal apoptosis. ConclusionsOur findings suggest that it may be feasible to confer neuroprotection against hypoxia-induced dopamine dysfunction to newborns likely to experience hypoxic insults. This could significantly improve the outcomes of those 8–11% of newborns who would otherwise experience hypoxia-induced behavioral, motor and cognitive dysfunction.

Eliminating medullary 5-HT neurons delays arousal and decreases the respiratory response to repeated episodes of hypoxia in neonatal rat pups.

Arousal from sleep is a critical defense mechanism when infants are exposed to hypoxia, and an arousal deficit has been postulated as contributing to the etiology of the sudden infant death syndrome (SIDS). The brainstems of SIDS infants are deficient in serotonin (5-HT) and tryptophan hydroxylase (TPH) and have decreased binding to 5-HT receptors. This study explores a possible connection between medullary 5-HT neuronal activity and arousal from sleep in response to hypoxia. Medullary raphe 5-HT neurons were eliminated from neonatal rat pups with intracisterna magna (CM) injections of 5,7-dihydroxytryptamine (DHT) at P2-P3. Each pup was then exposed to four episodes of hypoxia during sleep at three developmental ages (P5, P15, and P25) to produce an arousal response. Arousal, heart rate, and respiratory rate responses of DHT-injected pups were compared with pups that received CM artificial cerebrospinal fluid (aCSF) and those that received DHT but did not have a significant reduction in medullary 5-HT neurons. During each hypoxia exposure, the time to arousal from the onset of hypoxia (latency) was measured together with continuous measurements of heart and respiratory rates, oxyhemoglobin saturation, and chamber oxygen concentration. DHT-injected pups with significant losses of medullary 5-HT neurons exhibited significantly longer arousal latencies and decreased respiratory rate responses to hypoxia compared with controls. These results support the hypothesis that in newborn and young rat pups, 5-HT neurons located in the medullary raphe contribute to the arousal response to hypoxia. Thus alterations medullary 5-HT mechanisms might contribute to an arousal deficit and contribute to death in SIDS infants.

Posture effects on spontaneous limb movements, alternated stepping, and the leg extension response in neonatal rats

The development of postural control is considered an important factor for the expression of coordinated behavior such as locomotion. In the natural setting of the nest, newborn rat pups adapt their posture to perform behaviors of ecological relevance such as those related to suckling. The current study explores the role of posture in the expression of three behaviors in the newborn rat: spontaneous limb activity, locomotor-like stepping behavior, and the leg extension response (LER). One-day-old rat pups were tested in one of two postures – prone or supine – on each of these behavioral measures. Results showed that pups expressed more spontaneous activity while supine, more stepping while prone, and no differences in LER expression between the two postures. Together these findings show that posture affects the expression of newborn behavior patterns in different ways, and suggest that posture may act as a facilitator or a limiting factor in the expression of different behaviors during early development.

Proteomic Analysis of One-carbon Metabolism-related Marker in Liver of Rat Offspring

Maternal food intake has a significant effect on the fetal environment, and an inadequate maternal diet may result in intrauterine growth restriction. Intrauterine growth restriction newborn rat pups nursed by normal diet-fed dams exhibited rapid catch-up growth, which plays a critical role in the risk for metabolic and cardiovascular disease in later life. Specifically, one-carbon metabolism in the liver plays a critical role in placental and fetal growth. Impaired functioning of one-carbon metabolism is associated with increased homocysteine levels. In this study, we applied a comprehensive proteomic approach to identify differential expression of proteins related to one-carbon metabolism in the livers of rat offspring as an effect of maternal food restriction during gestation. Data are available via ProteomeXchange with identifier PXD002578. We determined that betaine-homocysteine S-methyltransferase 1, methylenetetrahydrofolate dehydrogenase 1, and ATP synthase subunit beta mitochondrial (ATP5B) expression levels were significantly reduced in the livers of rat offspring exposed to maternal food restriction during gestation compared with in the offspring of rats fed a normal diet (p < 0.05). Moreover, the expression levels of betaine-homocysteine S-methyltransferase 1, methylenetetrahydrofolate dehydrogenase 1, and ATP synthase subunit beta mitochondrial were negatively correlated with serum homocysteine concentration in male offspring exposed to maternal food restriction during gestation and normal diet during lactation. However, in female offspring only expression levels of methylenetetrahydrofolate dehydrogenase 1 were negatively correlated with homocysteine concentration. This study shows that maternal food restriction during late gestation and normal diet during lactation lead to increased homocysteine concentration through disturbance of one-carbon metabolism in the livers of male offspring. This suggests that male offspring have an increased gender-specific susceptibility to disease in later life through fetal programming.

Fluctuation of blood glucose level in newborn rats depending on the season and spontaneous motor activity pattern

Previously, we demonstrated that in newborn rat pups the blood glucose level changes depending on the spontaneous periodic motor activity (SPMA) pattern. During rest periods, both under dominant decasecond and minute rhythms, the blood glucose level is higher than during activity periods. We also showed that the blood glucose level rises with age reaching the “adult” level by day 10. In the present study conducted on 3–10-day-old rat pups under free behavior conditions, the blood glucose level has been examined at different periods of the activity–rest cycle and at different seasons. It has been established that in newborn rats at all ages tested (3, 5, 7 and 10 days) the lowest glucose concentration occurs in winter. In spring, the glucose level increases reaching its maximum in summer when it is significantly different from those in winter and spring in all age groups except for day 5. In autumn, the glucose level decreases approaching its spring values but still differing significantly from the winter values. In 5-day-old rats, no significant changes in the glucose level at different seasons have been found. These data indicate seasonal fluctuations of the blood glucose level in newborn rats. Meanwhile, during all seasons except for spring the blood glucose level depends on the SPMA pattern. In spring, these differences are smoothed.

Impacts of β-estradiol on intestinal injury in newborn rats

Objective: Necrotizing enterocolitis has been investigated and debated extensively in recent years; however, there is still no effective treatment. The aim of this study was thus to examine the effects of β-estradiol on intestinal injury in rats.Methods: Twenty-four newborn female rat pups were divided into three groups. In group 1 (sham), hypoxia–re-oxygenation was not performed. In group 2 (saline), the rats were injected with saline after hypoxia–re-oxygenation, and the process was repeated for 5 d. In group 3 (β-estradiol treatment), the rats were subjected to hypoxia–re-oxygenation and then given β-estradiol intraperitoneally once a day for 5 d. After these procedures, the terminal ileum was removed for analysis.Results: Statistically significant differences in histological grades were found between groups 1 and 2 (p = 0.000), groups 1 and 3 (p = 0.028), and groups 2 and 3 (p = 0.021). There were also differences in TNF-α and IL-6 levels between groups 2 and 3 (p = 0.000 and p = 0.038, respectively) and between groups 1 and 2 (p = 0.000 and p = 0.000); there was no difference between groups 1 and 3 (p = 0.574 and p = 0.195, respectively). Electron microscopy examination revealed a decrease in lipid droplets at the apical cytoplasm of the columnar cells in group 2; in group 3, the absorption of the lipids as lipid droplets was similar to that of group 1.Conclusion: In this study, β-estradiol was found to decrease the intensity of intestinal injury significantly by inhibiting TNF-α and IL-6.