Postnatal Time Research Articles

Inhibition of striatal indirect pathway during second postnatal week leads to long-lasting deficits in motivated behavior.

Schizophrenia is a neuropsychiatric disorder with postulated neurodevelopmental etiology. Genetic and imaging studies have shown enhanced dopamine and D2 receptor occupancy in the striatum of patients with schizophrenia. However, whether alterations in postnatal striatal dopamine can lead to long-lasting changes in brain function and behavior is still unclear. Here, we approximated striatal D2R hyperfunction in mice via designer receptor-mediated activation of inhibitory Gi-protein signaling during a defined postnatal time window. We found that Gi-mediated inhibition of the indirect pathway (IP) during postnatal days 8-15 led to long-lasting decreases in locomotor activity and motivated behavior measured in the adult animal. In vivo photometry further showed that the motivational deficit was associated with an attenuated adaptation of outcome-evoked dopamine levels to changes in effort requirements. These data establish a sensitive time window of D2R-regulated striatal development with long-lasting impacts on neuronal function and behavior.

Properties of rhythmogenic currents in spinal Shox2 interneurons across postnatal development.

Locomotor behaviors are performed by organisms throughout life, despite developmental changes in cellular properties, neural connectivity, and biomechanics. The basic rhythmic activity in the central nervous system that underlies locomotion is thought to be generated via a complex balance between network and intrinsic cellular properties. Within mature mammalian spinal locomotor circuitry, we have yet to determine which properties of spinal interneurons (INs) are critical to rhythmogenesis and how they change during development. Here, we combined whole cell patch clamp recordings, immunohistochemistry, and RNAscope targeting lumbar Shox2 INs in mice, which are known to be involved in locomotor rhythm generation. We focused on the properties of putatively rhythmogenic ionic currents and the expression of corresponding ion channels across postnatal time points in mice. We show that subsets of Shox2 INs display voltage-sensitive conductances, in addition to respective ion channels, which may contribute to or shape rhythmic bursting. Persistent inward currents, M-type potassium currents, slow afterhyperpolarization, and T-type calcium currents are enhanced with age. In contrast, the hyperpolarization-activated and A-type potassium currents were either found with low prevalence in subsets of neonatal, juvenile, and adult Shox2 INs or did not developmentally change. We show that Shox2 INs become more electrophysiologically diverse by juvenile and adult ages, when locomotor behavior is weight-bearing. These results suggest a developmental shift in the magnitude of rhythmogenic ionic currents and the expression of corresponding ion channels that may be important for mature, weight-bearing locomotor behavior.

Deep postnatal phenotyping of a new mouse model of nonketotic hyperglycinemia.

Nonketotic hyperglycinemia due to deficient glycine cleavage enzyme activity causes a severe neonatal epileptic encephalopathy. Current therapies based on mitigating glycine excess have only limited impact. An animal model with postnatal phenotyping is needed to explore new therapeutic approaches. We developed a Gldc p.Ala394Val mutant model and bred it to congenic status in two colonies on C57Bl/6J (B6) and J129X1/SvJ (J129) backgrounds. Mutant mice had reduced P-protein and enzyme activity indicating a hypomorphic mutant. Glycine levels were increased in blood and brain regions, exacerbated by dietary glycine, with higher levels in female than male J129 mice. Birth defects were more prevalent in mutant B6 than J129 mice, and hydrocephalus was more frequent in B6 (40%) compared to J129 (none). The hydrocephalus rate was increased by postnatal glycine challenge in B6 mice, more so when delivered from the first neonatal week than from the fourth. Mutant mice had reduced weight gain following weaning until the eighth postnatal week, which was exacerbated by glycine loading. The electrographic spike rate was increased in mutant mice following glycine loading, but no seizures were observed. The alpha/delta band intensity ratio was decreased in the left cortex in female J129 mice, which were less active in an open field test and explored less in a Y-maze, suggesting an encephalopathic effect. Mutant mice showed no evidence of memory dysfunction. This partial recapitulation of human symptoms and biochemistry will facilitate the evaluation of new therapeutic approaches with an early postnatal time window likely most effective.

A persistent mineralization process in alveolar bone throughout the postnatal growth stage in rats

ObjectiveAlveolar bone quality is essential for the maxillofacial integrity and function, and depends on alveolar bone mineralization. This study aims to investigate the in vivo changes in alveolar bone mineralization, from the perspective of mineral deposition and crystal transition in postnatal rats. DesignNine postnatal time points of Wistar rats, ranging from day 1 to 56, were set to obtain the maxillary alveolar bone samples. Each time point consisted of ninety rats, with 45 females and 45 males. Macromorphology of alveolar bone was reconducted by Micro-Computed Tomography and the mineral content was quantified via Thermogravimetric analysis, Scanning Electron Microscope, High-Resolution Transmission Electron Microscopy and vibrational spectroscopy. Furthermore, the crystallinity and composition were characterized by vibrational spectroscopy, X-ray Diffraction, X-ray Photoelectron Spectroscopy and Selected Area Electron Diffraction. ResultsThe progressive increase of mineral deposition was accompanied by substantial growth in alveolar bone mass and volume in postnatal rats. Whereas the mineral percentage initially decreased and then increased, reaching a nadir on postnatal day 14 (P14) when tooth eruption was first observed. Besides, localized mineralization was initiated by the formation of amorphous precursors and then converted into mineral crystals, while there was no statistically significant change in the average crystallinity of the bone during growth. ConclusionMineralization of alveolar bone is ongoing throughout the early growth in postnatal rats. Mineral deposition increases with age, whereas the crystallinity remains stable within a certain range. Besides, the mineral percentage reaches its lowest point on P14, which may be attributed to tooth eruption.

3,3',5-Triiodothyroacetic Acid Transporters.

Introduction: Thyroid hormone transporters are essential for thyroid hormones to enter target cells. Monocarboxylate transporter (MCT) 8 is a key transporter and is expressed at the blood-brain barrier (BBB), in neural cells and many other tissues. Patients with MCT8 deficiency have severe neurodevelopmental delays because of cerebral hypothyroidism and chronic sequelae of peripheral thyrotoxicosis. The T3 analog 3,3',5-triiodothyroacetic acid (TRIAC) rescued neurodevelopmental features in animal models mimicking MCT8 deficiency and improved key metabolic features in patients with MCT8 deficiency. However, the identity of the transporter(s) that facilitate TRIAC transport are unknown. Here, we screened candidate transporters that are expressed at the human BBB and/or brain-cerebrospinal fluid barrier and known thyroid hormone transporters for TRIAC transport. Materials and Methods: Plasma membrane expression was determined by cell surface biotinylation assays. Intracellular accumulation of 1 nM TRIAC was assessed in COS-1 cells expressing candidate transporters in Dulbecco's phosphate-buffered saline (DPBS)/0.1% glucose or Dulbecco's modified Eagle's medium (DMEM) with or without 0.1% bovine serum albumin (BSA). Expression of Slc22a8 was determined by fluorescent in situ hybridization in brain sections from wild-type and Mct8/Oatp1c1 knockout mice at postnatal days 12, 21, and 120. Results: In total, 59 plasma membrane transporters were selected for screening of TRIAC accumulation (n = 40 based on expression at the human BBB and/or brain-cerebrospinal fluid barrier and having small organic molecules as substrates; n = 19 known thyroid hormone transporters). Screening of the selected transporter panel showed that 18 transporters facilitated significant intracellular accumulation of TRIAC in DPBS/0.1% glucose or DMEM in the absence of BSA. In the presence of BSA, substantial transport was noted for SLCO1B1 and SLC22A8 (in DPBS/0.1% glucose and DMEM) and SLC10A1, SLC22A6, and SLC22A24 (in DMEM). The zebrafish and mouse orthologs of these transporters similarly facilitated intracellular accumulation of TRIAC. Highest Slc22a8 mRNA expression was detected in mouse brain capillary endothelial cells and choroid plexus epithelial cells at early postnatal time points, but was reduced at P120. Conclusions: Human SLC10A1, SLCO1B1, SLC22A6, SLC22A8, and SLC22A24 as well as their mouse and zebrafish orthologs are efficient TRIAC transporters. These findings contribute to the understanding of TRIAC treatment in patients with MCT8 deficiency and animal models thereof.

The ENCODE mouse postnatal developmental time course identifies regulatory programs of cell types and cell states.

Postnatal genomic regulation significantly influences tissue and organ maturation but is under-studied relative to existing genomic catalogs of adult tissues or prenatal development in mouse. The ENCODE4 consortium generated the first comprehensive single-nucleus resource of postnatal regulatory events across a diverse set of mouse tissues. The collection spans seven postnatal time points, mirroring human development from childhood to adulthood, and encompasses five core tissues. We identified 30 cell types, further subdivided into 69 subtypes and cell states across adrenal gland, left cerebral cortex, hippocampus, heart, and gastrocnemius muscle. Our annotations cover both known and novel cell differentiation dynamics ranging from early hippocampal neurogenesis to a new sex-specific adrenal gland population during puberty. We used an ensemble Latent Dirichlet Allocation strategy with a curated vocabulary of 2,701 regulatory genes to identify regulatory "topics," each of which is a gene vector, linked to cell type differentiation, subtype specialization, and transitions between cell states. We find recurrent regulatory topics in tissue-resident macrophages, neural cell types, endothelial cells across multiple tissues, and cycling cells of the adrenal gland and heart. Cell-type-specific topics are enriched in transcription factors and microRNA host genes, while chromatin regulators dominate mitosis topics. Corresponding chromatin accessibility data reveal dynamic and sex-specific regulatory elements, with enriched motifs matching transcription factors in regulatory topics. Together, these analyses identify both tissue-specific and common regulatory programs in postnatal development across multiple tissues through the lens of the factors regulating transcription.

Early onset of enamel formation in Baka pygmy’s deciduous canines

ObjectiveOur aim was to evaluate by enamel microstructure analysis two hypotheses that would explain the early dental eruption in the Bakaparticularity, a shorter crown formation time and/or earlier onset of crown formation. DesignDeciduous canines corresponds to the best teeth to perform the analysis of enamel microstructure. Longitudinal ground sections of 21 deciduous canines from 12 individuals were studied with transmitted light microscopy. Cross-striations, striaes of Retzius (SR) and the neonatal line (NNL) enable to establish the prenatal crown formation time (preCFT), the postnatal crown formation time (postCFT), the crown formation time (CFT) as well as the daily secretion rate (DSR) and the enamel extension rate (EER) and their variation along crown formation. ResultsThe DSR and the EER in the Baka are similar than in other populations with an average DSR of 3.26 µm and EER of 18.18 µm. The preCFT was 154 days, the postCFT 265 days and CFT 419 days. Comparison with other population does not show difference in CFT. However, the preCFT and the postCFT differ, the first is higher and the second lower in the Baka than in other populations. Furthermore, the number of prenatal areas of enamel was greater in the Baka. ConclusionOur analysis suggests that the Baka does not distinguish by a different CFT but the onset of crown formation is earlier than in other groups. Therefore, the early dental eruption in the Baka results from an earlier onset of crown formation.

Assessing the stability of psychobiological stress reactivity during adolescence: mixed-effect modelling of cortisol responses to laboratory stressors

Background Puberty has been historically considered as a time of risk and vulnerability for young people. It is associated with rapid development in the hypothalamus, which is central in the production of both stress and sex steroids. While patterns of stress reactivity are calibrated in early life, this time of rapid development may provide a means for these patterns to change. This purpose of this study was to examine whether patterns of cortisol reactivity remained stable across one year of pubertal development, and whether variations in pubertal development impacted on this stability. Methods This study used a secondary dataset comprised of 102 adolescent-aged children. Children took part in the Trier Social Stress Test to elicit a physiological stress response. Cortisol reactivity was measured as the increase in salivary cortisol concentration taken at five time points throughout the session. Pubertal stage was measured by nurse report where possible, and parent/self-report otherwise and was used to calculate pubertal timing and tempo relative to peers. Measures of anxiety, BMI, and socio-economic status were taken and included in analysis. Results Results of a linear mixed-effect model found there to be a significant difference in cortisol reactivity over time, indicating that stress reactivity did not remain stable during this time (Estimate= 3.39, t=3.67, p<.001, CI[1.56, 5.22]). Additionally, results show children who developed slower/quicker than peers displayed decreased stress reactivity (Estimate= -3.59, t=-2.13. p=.03, CI[-6.92, -0.25]). Conclusions This research contributes to a relatively small but consistent body of research noting pattern of increased cortisol reactivity during pubertal development. While a significant effect was found for pubertal tempo, this findings should not be considered indicative of any true effect.

Prenatal exposure to environmental toxins and comprehensive dental findings in a population cohort of children.

Environmental toxins are known to have many impacts on growth and development in humans, starting in utero. Alterations in amelogenesis, caused by chemical and physical trauma that occur during the antenatal, perinatal and postnatal time periods, may result in developmental defects in deciduous and permanent tooth enamel, as demonstrated in animal studies. These defects can be clinically visible and result in a variety of morphological and functional problems in the dentition. Since enamel does not remodel after formation, it may serve as a permanent record of insults during organ development.Our primary purpose was to investigate any possible relationship between intrauterine exposure to endocrine disrupting chemicals (phenols and phthalates) and developmental defects in enamel in children, while also accounting for fluoride exposure. Our secondary purpose was to report descriptively on findings from comprehensive dental examinations performed on 356 children that were drawn from the general paediatric population. A cohort of children from the Utah Children's Project (N = 356) that had full medical exams, comprehensive medical and family histories and available biospecimens were given extraoral and intraoral examinations. They also completed an oral health questionnaire. Standardized intraoral photographs were taken of the teeth and viewed by standardised examiners and the dental observations were recorded for a full inventory of findings, including: tooth morphology, caries, restorations, colorations, attrition, erosion, fractures and hypomineralization. Perinatal maternal urine samples were assessed for the concentration of fluoride, phenols and phthalates, including bisphenol A (BPA).Pairwise statistical analyses were done to correlate the dental findings with one another and with the presence of environment chemicals found in the urine samples. Hypomineralization was the most common finding (96% of children; 37% of deciduous teeth, 42% of permanent teeth), consistent with molar incisor hypomineralization (MIH) described in other human populations. No consistent correlations were seen between dental findings and the presence of phenols and phthalates in prenatal urine, but the number of samples available for the assessment was limited (n = 35).In conclusion, we found a high proportion of dental hypomineralization in a population based paediatric cohort, but did not find an association with prenatal exposure to phenols and phthalates.

Vitamin and mineral supplementation to beef heifers during gestation: impacts on morphometric measurements of the neonatal calf, vitamin and trace mineral status, blood metabolite and endocrine profiles, and calf organ characteristics at 30h after birth.

To examine the effects of feeding a vitamin and mineral supplement to beef heifers throughout gestation on mineral status and hormone/endocrine profiles in the dam and calf, and morphometric characteristics and organ mass of the calf at 30h after birth, Angus-based heifers (n = 72, 14 to 15mo of age, initial body weight [BW] = 380.4 ± 50.56kg) were estrus synchronized and artificially inseminated (AI) with female-sexed semen. Heifers were blocked by BW and randomly assigned to receive either a basal diet (CON; n = 36) or a basal diet plus a vitamin and mineral supplement (VTM; n = 36) via an individual feeding system beginning at breeding, with both diets targeting BW gains of 0.45kg heifer-1·d-1. Heifers not pregnant after the first AI (CON, n = 19; VTM, n = 18) were rebred via AI 60d after treatment initiation, and heifers gestating female fetuses (CON, n = 7; VTM, n = 7) received treatments throughout gestation and were experimental units for this study. Calves were separated from their dams and fed colostrum replacer within 2h of birth and euthanized 30h after the first feeding. Calf morphometrics were recorded, and tissues were weighed and sampled. Serum from the dam at calving and serum, liver, and muscle from the calf at 30h were analyzed for concentrations of minerals. Serum from the dam and calf were analyzed for concentrations of leptin, vitamins A, D, and E, cortisol, growth hormone, and insulin-like growth factor 1. All response variables were analyzed using the MIXED procedure of SAS. Calf body morphometrics and BW of the dam at calving (P ≥ 0.32), calf organ weights (P ≥ 0.21), and calf ovarian follicle counts (P ≥ 0.13) were not affected by maternal treatment. Concentrations of Se and Co in calf serum and Se in calf liver were increased (P ≤ 0.02) in VTM. Serum concentrations of Co and vitamin A in the dam were greater (P ≤ 0.01) in supplemented compared with nonsupplemented dams, and serum concentrations of vitamin D were greater (P ≤ 0.0003) in supplemented dams and calves compared with the nonsupplemented cohort. Maternal supplementation supported vitamin and mineral status in the neonate, yet had no discernable impact on BW, organ mass, or circulating hormones/metabolites in the calf. Evaluating offspring at later postnatal time points is warranted to determine if prenatal vitamin and mineral supplementation affects performance, health, metabolism, and efficiency of energy utilization in key metabolic tissues in the calf.

Hydrogen Sulfide Promotes Postnatal Cardiomyocyte Proliferation by Upregulating SIRT1 Signaling Pathway.

Hydrogen sulfide (H2S) has been identified as a novel gasotransmitter and a substantial antioxidant that can activate various cellular targets to regulate physiological and pathological processes in mammals. However, under physiological conditions, it remains unclear whether it is involved in regulating cardiomyocyte (CM) proliferation during postnatal development in mice. This study mainly aimed to evaluate the role of H2S in postnatal CM proliferation and its regulating molecular mechanisms. We found that sodium hydrosulfide (NaHS, the most widely used H2S donor, 50-200 μM) increased neonatal mouse primary CM proliferation in a dose-dependent manner in vitro. Consistently, exogenous administration of H2S also promoted CM proliferation and increased the total number of CMs at postnatal 7 and 14 days in vivo. Moreover, we observed that the protein expression of SIRT1 was significantly upregulated after NaHS treatment. Inhibition of SIRT1 with EX-527 or si-SIRT1 decreased CM proliferation, while enhancement of the activation of SIRT1 with SRT1720 promoted CM proliferation. Meanwhile, pharmacological and genetic blocking of SIRT1 repressed the effect of NaHS on CM proliferation. Taken together, these results reveal that H2S plays a promotional role in proliferation of CMs in vivo and in vitro and SIRT1 is required for H2S-mediated CM proliferation, which indicates that H2S may be a potential modulator for heart development in postnatal time window.

Cleaved caspase-3 is present in the majority of glial cells in the intact rat spinal cord during postnatal life

Cell death is an essential process that occurs during the development of the central nervous system. Despite the availability of a wide range of commercially produced antibodies against various apoptotic markers, data regarding apoptosis in intact spinal cord during postnatal development and adulthood are mostly missing. We investigated apoptosis in rat spinal cord at different stages of ontogenesis (postnatal days 8, 29, and 90). For this purpose, we applied immunofluorescent detection of two widely used apoptotic markers, cleaved caspase-3 (cC3) and cleaved poly(ADP-ribose) polymerase (cPARP). Surprisingly, we found significant discrepancy between the number of cC3+ cells and PARP+ cells, with a ratio between 500:1 and 5000:1 in rat spinal cord at all postnatal time points. The majority of cC3+ cells were glial cells and did not exhibit an apoptotic phenotype. In contrast with in vivo results, in vitro analysis of primary cell cultures derived from neonatal rat spinal cord and treated with the apoptotic inductor staurosporine revealed a similar onset of occurrence of both cC3 and cPARP in cells subjected to apoptosis. Gene expression analysis of spinal cord revealed elevated expression of the Birc4 (XIAP), Birc2, and Birc5 (Survivin) genes, which are known potent inhibitors of apoptosis. Our data indicate that cC3 is not an exclusive marker of apoptosis, especially in glial cells, owing its possible presence in inhibited forms and/or its participation in other non-apoptotic roles. Therefore, cPARP appears to be a more appropriate marker to detect apoptosis.

Effects of maternal taxane chemotherapy exposure on daughters’ ovarian reserve and fertility potential

To investigate the long-term effects of in utero taxane exposure on exposed daughters' ovarian reserve and reproductive potential. Pregnant dams were treated with a single, human-relevant animal-equivalent dose of saline, docetaxel, or paclitaxel at embryonic day 16.5. In utero-exposed daughters were aged to multiple postnatal time points for ovarian and endocrine analysis or were bred to assess fertility and fecundity. Granddaughters of treated dams were assessed also for ovarian follicle composition and atresia. Laboratory study. C57BL/6 mice. In utero exposure to saline, docetaxel, or paclitaxel. Ovarian follicle composition, rates of follicle atresia, and rates of multioocyte follicles were analyzed in all exposure groups. Serum hormone levels and oocyte retrieval outcomes following ovarian hyperstimulation were also assessed. Finally, animals from all exposure groups were bred with the number of litters, pups per litter, live births, interlitter time interval, and age at the last litter analyzed. We found that docetaxel and paclitaxel exposure in utero results in ovarian toxicity later in life, significantly affecting folliculogenesis as well as increasing the rate of follicular abnormalities, including follicle atresia and multioocyte follicles. Furthermore, viability staining indicates that the ovaries of daughters exposed to taxanes in utero demonstrate a significantly higher number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive follicles. Hormone measurements also revealed that serum follicle-stimulating hormone concentration was significantly altered in taxane-exposed daughters, with the ratio of luteinizing hormone to follicle-stimulating hormone significantly elevated, specifically after paclitaxel exposure, coincident with the inability of these animals to properly respond to ovarian stimulation. Breeding studies over the course of a year also suggest that these taxane-exposed mice are fertile, although the duration of their fertility is shortened and they produce significantly fewer litters. Finally, ovarian effects are apparent in granddaughters of mice treated with docetaxel, suggesting persistent and multigenerational effects of taxane exposure. Our studies demonstrate that in utero exposure to taxane-based therapy during late gestation has a significant effect on the long-term reproductive health of exposed daughters (as well as their daughters) and will be instrumental in helping clinicians better understand which chemotherapies for maternal malignancy are least detrimental to a developing fetus.

MDM2 Regulation of HIF Signaling Causes Microvascular Dysfunction in Hypertrophic Cardiomyopathy.

Microvasculature dysfunction is a common finding in pathologic remodeling of the heart and is thought to play an important role in the pathogenesis of hypertrophic cardiomyopathy (HCM), a disease caused by sarcomere gene mutations. We hypothesized that microvascular dysfunction in HCM was secondary to abnormal microvascular growth and could occur independent of ventricular hypertrophy. We used multimodality imaging methods to track the temporality of microvascular dysfunction in HCM mouse models harboring mutations in the sarcomere genes Mybpc3 (cardiac myosin binding protein C3) or Myh6 (myosin heavy chain 6). We performed complementary molecular methods to assess protein quantity, interactions, and post-translational modifications to identify mechanisms regulating this response. We manipulated select molecular pathways in vivo using both genetic and pharmacological methods to validate these mechanisms. We found that microvascular dysfunction in our HCM models occurred secondary to reduced myocardial capillary growth during the early postnatal time period and could occur before the onset of myocardial hypertrophy. We discovered that the E3 ubiquitin protein ligase MDM2 (murine double minute 2) dynamically regulates the protein stability of both HIF1α (hypoxia-inducible factor 1 alpha) and HIF2α (hypoxia-inducible factor 2 alpha)/EPAS1 (endothelial PAS domain protein 1) through canonical and noncanonical mechanisms. The resulting HIF imbalance leads to reduced proangiogenic gene expression during a key period of myocardial capillary growth. Reducing MDM2 protein levels by genetic or pharmacological methods normalized HIF protein levels and prevented the development of microvascular dysfunction in both HCM models. Our results show that sarcomere mutations induce cardiomyocyte MDM2 signaling during the earliest stages of disease, and this leads to long-term changes in the myocardial microenvironment.

Ornidazole Transfer into Colostrum and Assessment of Exposure Risk for Breastfeeding Infant: A Population Pharmacokinetic Analysis.

Ornidazole is frequently used for the prevention and treatment of anaerobic infections after caesarean section. There is still a lack of data on the excretion of ornidazole in breast milk. Therefore, the aim of this study was to investigate the transfer of ornidazole into colostrum and to assess the risk of infant exposure to the drug via breast milk. Population pharmacokinetic analysis was conducted using datasets of plasma and milk concentrations obtained from 77 breastfeeding women to examine the excretion kinetics of ornidazole. Various factors that may affect the excretion of ornidazole were investigated. The final model was then used to simulate ornidazole concentration-time profiles in both plasma and milk. The drug exposure in body fluids and the potential risk for breastfeeding were assessed based on the safety threshold. Plasma ornidazole concentration data could be described well by a one-compartment model, and concentrations in breast milk were linked to this model using an estimated milk-to-plasma concentration ratio (MPRcon). Significant variables that influenced drug exposure and MPRcon were identified as total bilirubin levels (TBIL) and postnatal sampling time, respectively. Simulations showed that women with abnormal liver function (TBIL > 17 μmol/L) had higher ornidazole levels in plasma and milk than those with normal liver function (TBIL < 17 μmol/L), but the exposures through colostrum of lactating women from both groups were below the safety threshold. This work provides a simple and feasible strategy for the prediction of drug exposure in breast milk and the assessment of breastfeeding safety.

THU135 Maternal Obesogenic Diet Exposure Affects Post-natal And Pathologic Hepatocyte Proliferation In Offspring

Abstract Disclosure: N. Ramavath: None. H. Hinrichs: None. M. Young: None. M. Thompson: None. Background: Obesity is a complex metabolic syndrome associated with a wide range of abnormalities in liver known as non-alcoholic fatty liver diseases (NAFLD). Evidence supports that maternal obesity/obesogenic diet exposure programs increased NAFLD offspring. The liver responds to lipotoxic hepatocyte injury through hepatocyte proliferation. It is not clear whether maternal obesogenic diet exposure affects the capacity of offspring hepatocytes to proliferate. We hypothesized that early impact of maternal/ obesogenic diet exposure in early life or utero exposure enhances hepatocyte proliferation capacity in offspring. Methods: Female mice were fed chow or high fat-fructose-cholesterol (HFFC) diet for 6 weeks and bred with lean males Liver and serum samples were collected at different postnatal time periods 5, 10, 15, 20, 25, and 30 days to analyze histological and molecular markers for liver proliferation. In addition, a small group of offspring from each group were weaned to the HFFC diet for 7 weeks to analyze progression of NAFLD (non -alcoholic fatty liver diseases). Results: No significant difference between neonatal body weight and liver weight was observed; however, the liver weight/body weight was increased at day 20 in HFFC offspring compared to chow offspring. The number of ki-67 positive hepatocytes peaked in both groups at day 15. An increase in ki-67 positive hepatocytes was observed at 15, 20, and 30 days in HFFC offspring compared to chow offspring. After 7 weeks of HFFC diet feeding, the number of Ki-67 positive hepatocytes was higher in HFFC offspring in comparison with Chow offspring. Conclusion: Maternal obesogenic diet exposure affected post-natal and NAFLD-associated hepatocyte proliferation in offspring with an increase in hepatocyte proliferative capacity. This could have implications for the ability of maternal obesity exposed offspring to respond to hepatic injury and potential for development of hepatic cancer. Presentation: Thursday, June 15, 2023

Single-cell dynamics of liver development in postnatal pigs

The postnatal development of the liver, an essential organ for metabolism and immunity, remains poorly characterized at the single-cell resolution. Here, we generated single-nucleus and single-cell transcriptomes of 84,824 pig liver cells at four postnatal time points: day 30, 42, 150, and 730. We uncovered 23 cell types, including three rare cell types: plasmacytoid dendritic cells, CAVIN3+IGF2+ endothelial cells, and EBF1+ fibroblasts. The latter two were verified by multiplex immunohistochemistry. Trajectory and gene regulatory analyses revealed 33 genes that encode transcription factors associated with hepatocyte development and function, including NFIL3 involved in regulating hepatic metabolism. We characterized the spatiotemporal heterogeneity of liver endothelial cells, identified and validated leucine zipper protein 2 (LUZP2) as a novel adult liver sinusoidal endothelial cell-specific transcription factor. Lymphoid cells (NK and T cells) governed the immune system of the pig liver since day 30. Furthermore, we identified a cluster of tissue-resident NK cells, which displayed virus defense functions, maintained proliferative features at day 730, and manifested a higher conservative transcription factor expression pattern in humans than in mouse liver. Our study presents the most comprehensive postnatal liver development single-cell atlas and demonstrates the metabolic and immune changes across the four age stages.

Plasticity of thalamocortical axons is regulated by serotonin levels modulated by preterm birth

Sensory inputs are conveyed to distinct primary areas of the neocortex through specific thalamocortical axons (TCA). While TCA have the ability to reorient postnatally to rescue embryonic mistargeting and target proper modality-specific areas, how this remarkable adaptive process is regulated remains largely unknown. Here, using a mutant mouse model with a shifted TCA trajectory during embryogenesis, we demonstrated that TCA rewiring occurs during a short postnatal time window, preceded by a prenatal apoptosis of thalamic neurons-two processes that together lead to the formation of properly innervated albeit reduced primary sensory areas. We furthermore showed that preterm birth, through serotonin modulation, impairs early postnatal TCA plasticity, as well as the subsequent delineation of cortical area boundary. Our study defines a birth and serotonin-sensitive period that enables concerted adaptations of TCA to primary cortical areas with major implications for our understanding of brain wiring in physiological and preterm conditions.

The use of transcutaneous bilirubin nomograms for the prevention of bilirubin neurotoxicity in the neonates.

Although neonatal jaundice is a ubiquitous and predominantly benign phenomenon, the risk of neurotoxicity exists in a number of infants with unconjugated hyperbilirubinemia. Plotting bilirubin values on nomograms enables clinicians to employ an anticipatory and individualized approach with the goal of avoiding excessive hyperbilirubinemia and preventing acute bilirubin encephalopathy and its progression to kernicterus. We aimed to construct nomograms for White term infants based on transcutaneous bilirubin (TcB) measurements using a JM-105 device. TcB measurements were taken in infants at ages ranging from 0 to 96 postnatal hours. We then constructed hour-specific TcB nomograms from forehead and sternum measurements in infants who did not require subsequent phototherapy. We included 2,981 TcB measurements taken on the forehead and 2,977 measurements taken on the sternum in 301 White term newborn infants. We assessed the predictive abilities of the nomograms at six postnatal time intervals using receiver operating characteristic curves. The areas under the curves indicated reasonable prediction of hyperbilirubinemia requiring phototherapy, except for the forehead measurement taken within the first 12 h of life. Sensitivity tended to rise as postnatal age increased. The nomograms illustrate dermal bilirubin dynamics in White term neonates during the first 4 days of life. They may be useful tools to predict individualized risk of hyperbilirubinemia requiring treatment, and to plan optimal follow-up of infants at risk of bilirubin neurotoxicity.

Biochemical and Anthropometric Parameters for the Early Recognition of the Intrauterine Growth Restriction and Preterm Neonates at Risk of Impaired Neurodevelopment.

S100B and Tau are implicated with both brain growth and injury. Their urinary levels in 30-to-40-day-old full-term, preterm, IUGR, and preterm-IUGR subjects were measured to investigate their possible relationship with future delayed neurodevelopment. Values were related to the neuro-behavioral outcome at two years of age, as well as to brain volumes and urinary NGF assessed at the same postnatal time point. Using the Griffiths III test, cognitive and motor performances were determined to establish subgroups characterized by either normal or impaired neuro-behavior. The latter included preterm, IUGR, and preterm-IUGR individuals who exhibited significantly higher and lower S100B and Tau levels, respectively, along with markedly reduced cerebral volumes and urinary NGF, as previously demonstrated. Contrary to NGF, however, Tau and S100B displayed a weak correlation with brain volumes. Delayed cognitive and motor performances observed in two-year-old preterm and IUGR-born individuals were also found to be associated with anomalous urinary levels of S100B and Tau, assessed at 30-40 days of the postnatal period, and their changes did not correlate with brain growth. Thus, our data suggests that, in addition to cerebral volumes and NGF, urinary S100B and Tau can also be considered as valuable parameters for the early detection of future neurodevelopmental abnormalities.