Vascular topology is acutely impacted by experimental febrile status epilepticus

Febrile status epilepticus (FSE) is an important risk factor for temporal lobe epilepsy and early identification is vital. In a rat model of FSE, we identified an acute novel MRI signal in the basolateral amygdala (BLA) at 2 hours post FSE that predicted epilepsy in adulthood. This signal remains incompletely understood and hypothesized that it might derive from changes to vascular topology. Experimental FSE was induced in rat pups and compared to normothermic littermate controls. We examined cerebral vascular topology at 2 hours, using a novel vessel painting and analysis protocol. Blood vessel density of the cortical vasculature was significantly reduced in FSE rats, and this effect was lateralized, as reported for the MRI signal. The middle cerebral artery (MCA) exhibited abnormal topology in FSE pups but not in controls. In the BLA, significant vessel junction reductions and decreased vessel diameter were observed, together with a strong trend for reduced vessel length. In summary, FSE results in acute vascular topological changes in the cortex and BLA that may underlie the acute MRI signal that predicts progression to future epilepsy. The altered vasculature may be amenable to intervention treatments to potentially reduce the probability of progression to epilepsy following FSE.

The Multi-Component Causes of Late Neonatal Sepsis—Can We Regulate Them?

Elucidating the mechanisms of bacterial translocation is crucial for the prevention and treatment of neonatal sepsis. In the present study, we aimed to evaluate the potential of lactoferrin to inhibit the development of late-onset blood infection in neonates. Our investigation evaluates the role of key stress factors leading to the translocation of intestinal bacteria into the bloodstream and, consequently, the development of life-threatening sepsis. Three stress factors, namely weaning, intraperitoneal administration of Gram-positive cocci and oral intake of Gram-negative rods, were found to act synergistically. We developed a novel model of rat pups sepsis induced by bacterial translocation and observed the inhibition of this process by supplementation of various forms of lactoferrin: iron-depleted (apolactoferrin), iron-saturated (hololactoferrin) and manganese-saturated lactoferrin. Additionally, lactoferrin saturated with manganese significantly increases the Lactobacillus bacterial population, which contributes to the fortification of the intestinal barrier and inhibits the translocation phenomenon. The acquired knowledge can be used to limit the development of sepsis in newborns in hospital neonatal intensive care units.

Oral administration of TiO2 nanoparticles during early life impacts cardiac and neurobehavioral performance and metabolite profile in an age- and sex-related manner

Background Nanoparticles (NPs) are increasingly incorporated in everyday products. To investigate the effects of early life exposure to orally ingested TiO2 NP, male and female Sprague–Dawley rat pups received four consecutive daily doses of 10 mg/kg body weight TiO2 NP (diameter: 21 ± 5 nm) or vehicle control (water) by gavage at three different pre-weaning ages: postnatal day (PND) 2–5, PND 7–10, or PND 17–20. Cardiac assessment and basic neurobehavioral tests (locomotor activity, rotarod, and acoustic startle) were conducted on PND 20. Pups were sacrificed at PND 21. Select tissues were collected, weighed, processed for neurotransmitter and metabolomics analyses. Results Heart rate was found to be significantly decreased in female pups when dosed between PND 7–10 and PND 17–20. Females dosed between PND 2–5 showed decrease acoustic startle response and when dosed between PND 7–10 showed decreased performance in the rotarod test and increased locomotor activity. Male pups dosed between PND 17–20 showed decreased locomotor activity. The concentrations of neurotransmitters and related metabolites in brain tissue and the metabolomic profile of plasma were impacted by TiO2 NP administration for all dose groups. Metabolomic pathways perturbed by TiO2 NP administration included pathways involved in amino acid and lipid metabolism. Conclusion Oral administration of TiO2 NP to rat pups impacted basic cardiac and neurobehavioral performance, neurotransmitters and related metabolites concentrations in brain tissue, and the biochemical profiles of plasma. The findings suggested that female pups were more likely to experience adverse outcome following early life exposure to oral TiO2 NP than male pups. Collectively the data from this exploratory study suggest oral administration of TiO2 NP cause adverse biological effects in an age- and sex-related manner, emphasizing the need to understand the short- and long-term effects of early life exposure to TiO2 NP.

Prenatal administration of heparin-binding epidermal growth factor-like growth factor in an experimental model of necrotizing enterocolitis decreased both incidence and severity of the disease

BackgroundNecrotizing enterocolitis (NEC) is the leading gastrointestinal cause of death in premature infants and causes long-term disabilities. Previously, enteral heparin-binding epidermal growth factor-like growth factor (HB-EGF) administered after birth demonstrated decreased incidence and severity of NEC in a neonatal animal model of NEC. We investigated the potential prophylactic strategy of preventing NEC using prenatally administered HB-EGF.MethodsAn HB-EGF (800 µg/kg/dose) dose was injected into pregnant rats via tail vein or intraperitoneal route 2 hours prior to delivery. After cesarean section (C-section) at 21 days’ gestation, the rat pups were subjected to the NEC protocol by inducing stressors: hypoxia, hypothermia, hypertonic feeds, and orogastric gavage of lipopolysaccharide (2 mg/kg). Postnatally, pups were monitored for 96 hours and assessed for the development of clinical and postmortem histological NEC.ResultsThe experimental NEC incidence in untreated, stressed rat pups was 66%. Compared with untreated pups, the maternal administration of HB-EGF correlated with a significant NEC incidence and severity decrease in rat pups. The strongest decrease was seen when HB-EGF was administered via the intraperitoneal route 2 hours prior to C-section (66% vs 31%, *p<0.05). Prenatal HB-EGF administration significantly increased pups’ survival after NEC protocol exposure, with the greatest benefit observed in the group that received HB-EGF intraperitoneally 2 hours before delivery.ConclusionsPrenatal administration of HB-EGF decreases the incidence and severity of NEC, preserves gut barrier function and increases survival. This may represent a novel prophylactic clinical strategy for NEC offered to mothers at risk of delivering a premature infant.

Neonatal action of the dipeptidyl peptidase iv inhibitor diprotin A leads to a hyperactive phenotype formation and a prolonged increase in aggressiveness in rats

Введение. Ингибиторы пролинспецифической сериновой протеазы дипептидилпептидазы IV (ДПП-IV, CD26, EC 3.4.14.5), способные модулировать широкий спектр физиологических процессов, находят применение в клинике. В наших работах получены свидетельства влияния ингибиторов ДПП-IV при их введении в раннем постнатальном периоде на эмоционально-мотивационное поведение взрослых крыс. Более сильные изменения в поведении отмечались у крыс при действии ингибитора ДПП-IV дипротина А. Однако не ясно, как долго сохраняются такие изменения. Цель работы - изучение отсроченных эффектов ингибитора ДПП-IV дипротина А на выраженность эмоционально-мотивационных расстройств, индуцированных действием ингибитора в раннем постнатальном периоде, в динамике взросления крыс от 2 до 7 мес. Методика. Дипротин А вводили крысятам ежедневно в 5-18-й постнатальные дни внутрибрюшинно (2 мг/кг), в объеме 0.1 мл на 10 г массы тела. Крысята контрольной группы получали инъекции физиологического раствора. Поведение взрослых крыс оценивали в возрасте 2 и 7 мес в тестах автоматизированного «открытого поля», «Приподнятый крестообразный лабиринт» (ПКЛ), принудительного плавания и социального взаимодействия. Уровень кортикостерона в сыворотке крови определяли методом твердофазного иммуноферментного анализа ELISA. Для статистической обработки результатов использовали двухфакторный дисперсионный анализ Two Way ANOVA и непараметрический U-критерий Манна-Уитни с поправкой на множественность сравнений. Результаты. У крыс опытной группы по сравнению с контрольной группой в возрасте 2 и 7 мес была повышена двигательная активность и скорость перемещения в тесте ПКЛ. В возрасте 7 мес у них также была увеличена вертикальная исследовательская активность. Признаков повышения тревожности не выявлено. У крыс опытной группы выявлены признаки депрессивно-подобного поведения по нарушению биоритмологической структуры плавания, более выраженные в возрасте 7 мес. Неагрессивное социальное взаимодействие у крыс, получавших неонатально дипротин А, было снижено по сравнению с контролем в возрасте 2 мес, а в возрасте 7 мес, напротив, увеличено. У этих животных число и длительность агрессивных социальных контактов были увеличены по сравнению с контролем как в возрасте 2, так и в возрасте 7 мес. Уровень кортикостерона в сыворотке крови у крыс опытной группы в возрасте 7.5 мес был выше, чем в контроле. Заключение. Данные настоящего исследования свидетельствуют о развитии гиперактивного фенотипа и длительных психоэмоциональных нарушений в виде повышенной агрессивности наряду с активацией гипоталамо-гипофизарно-адреналовой оси у взрослых крыс, подвергнутых действию дипротина А в 5-18-й постнатальные дни, и поддерживают представления об участии дипептидилпептидазы-IV в генезе психоэмоциональных расстройств. Background. Inhibitors of the proline-specific serine protease dipeptidyl peptidase IV (DPP-IV, CD26, EC 3.4.14.5) may modulate a wide range of physiological processes and are used in the clinic. In our studies, we obtained evidence for the impact of DPP-IV inhibitors on adult rats’ emotional and motivational behavior when administered in the early postnatal period. Diprotin A exhibited the most significant impact on the animals’ behaviors. However, it is not clear how long the changes persist. Aim. To study the delayed effects of the DPP-IV inhibitor diprotin A on the severity of emotional and motivational disorders induced by the inhibitor action in the early postnatal period, in the dynamics of rats maturation from 2 to 7 months. Methods. Diprotin A was administered to rat pups daily on postnatal days 5-18, intraperitoneally, at a dose of 2 mg/kg, in a volume of 0.1 ml per 10 g of body weight. The rat pups of the control group received saline. The behavior of adult rats was assessed at the age of 2 and 7 months in the automated “open field,” “Elevated Plus Maze” (EPM), forced swimming, and social interaction tests. Serum corticosterone levels were determined by ELISA. The results were statistically processed using Two Way ANOVA and nonparametric Mann-Whitney U-test adjusted for multiple comparisons. Results. Experimental rats increased motor activity and travel speed in the EPM test compared with the control group at 2 and 7 months of age. At the age of 7 months, experimental rats also increased vertical (rearing) activity. There were no signs of increased anxiety. Experimental rats demonstrated depression-like behavior judged by the biorhythmologic structure of swimming, more pronounced at 7 months. Non-aggressive social interaction in rats treated neonatally with diprotin A was reduced compared with controls at the age of 2 months and, on the contrary, increased at the age of 7 months. In these animals, the number and duration of aggressive social contacts were increased compared with controls at the ages of 2 and 7 months. Serum corticosterone levels in experimental rats at the age of 7.5 months were higher than in control. Conclusion. The present study results testify to the development of a hyperactive phenotype and prolonged psychoemotional disorders as increased aggressiveness along with hypothalamic-pituitary-adrenal axis activation in adult rats exposed to the action of diprotin A on postnatal days 5-18. The data support the dipeptidyl peptidase IV involvement in the genesis of psychoemotional disorders.

Activation of TRESK background potassium channels by cloxyquin exerts protective effects against excitotoxic-induced brain injury and neuroinflammation in neonatal rats

The excitotoxicity is a common pathological mechanism of perinatal brain injuries (PBI), however neuroinflammation resulting in PBI is both a cause and a consequence of excitotoxicity. TRESK background potassium channels are an important regulator of neuronal excitability. We therefore investigated effects of activation of TRESK channels by selective activator cloxyquin on excitotoxic-induced brain injury and neuroinflammation involving brain mast cells and inflammatory cytokines in neonatal rats. An excitotoxic model mimicking human perinatal brain lesions was established via intracerebral injection of the glutamatergic agonist ibotenate to into newborn rats. P5 rat pups were intraperitoneally pretreated with vehicle, three different doses of cloxyquin (0.2, 1 and 5 mg/kg), or NMDA receptor antagonist MK-801 (positive control) 30 minutes prior to intracerebral injection of 10 µg ibotenate. Rat pups were sacrificed one or five days after the injury. Coronal brain sections were stained with cresyl-violet for histopathological examinations, and with toluidine-blue for brain mast cells assessments. Concentrations of activin A, IL-1β, IL-6 and IL-10 in brain homogenates were measured using ELISA. Cloxyquin dose-dependently ameliorated ibotenate-induced impairments in the cortical and white matter, and suppressed ibotenate-induced activation and number of brain mast cells. Moreover, cloxyquin dose-dependently reduced concentrations of activin A, IL-1β and IL-6 in the brain tissue induced by ibotenate while it elevated IL-10 level. Our findings reveal for the first time that cloxyquin, a selective activator of TRESK channels, dose-dependently exerted protective effects against excitotoxic-induced neonatal brain injury and neuroinflammation. TRESK channels may be a promising new target for the treatment of PBIs.

The deleterious effect of crossfostering in rat pups on hypoxic-ischemic injury tolerance and hypothermic neuroprotection

We study the effect of hypothermia (HT) following hypoxic-ischemic (HI) brain injury in postnatal day 7 (P7) rats. In 2015, new European Union animal transport regulations prompted a change in practice at the breeding facility, which henceforth crossfostered P3 litters to P8 older lactating dam prior to transportation. It is generally assumed that crossfostering does not significantly affect the experimental results. The aim of this study was to examine whether crossfostering affects our model consistency by modifying injury susceptibility and hypothermic neuroprotection. We analysed 219 pups (56 litters) from 11 experiments conducted between 2013 and 2015: 73 non-crossfostered and 146 crossfostered pups. At P7, all pups underwent unilateral common carotid artery ligation followed by 50min of hypoxia (8% O2, 36°C). Immediately after this mild insult, the pups were randomised to post-insult normothermia (NT) or HT treatment. Pups were culled at P14. Injury was assessed by area loss of the ipsilateral hemisphere and histopathology scoring of hippocampus, cortex, thalamus, and basal ganglia. Crossfostered pups had double the injury compared to non-crossfostered pups irrespective of treatment group. Hypothermic neuroprotection was statistically significant, but with a smaller and less consistent effect in crossfostered pups (relative neuroprotection 16% vs. 31% in non-crossfostered). These results demonstrate hypothermic neuroprotection following a mild HI insult. A representative subset of 41 animals were also assessed for evidence of microglial reactivity, however no detectable difference in microglial reactivity was observed between any of the groups. In conclusion, crossfostering alters outcomes in our established model through reduced insult tolerance and variable neuroprotection. Crossfostering as a common breeding practice is a largely unexplored variable in animal research that may result in invalid research conclusions if inadequately adjusted for by larger group sizes. As a result, crossfostering is likely to be inconsistent with the principles of replacement, reduction, and refinement.

Potential Mechanisms Underlying Hypoxia-Induced Diabetes in a Rodent Model: Implications for COVID-19

Previous studies reported that repetitive hypoxia in rat pups reduces insulin secretion and elevates fasting blood glucose levels; these sequelae persisted for several months. This report describes how episodic hypoxic events elevate a chloride ion exporter, K+-Cl− cotransporter-2 (KCC2), in the plasma membrane of insulin-secreting pancreatic β-cells. We assume that acute diabetic symptoms observed in rat pups with periodic oxygen desaturation could result from a lack of blood insulin levels due to disturbed β-cell function. This acute hypo-insulinemia may result from a disruption in chloride balance in β-cells arising from an imbalanced KCC2-NKCC1 (chloride exporter-importer) density as a consequence of periodic oxygen desaturation. Mechanistically, we postulate that a reduced insulin secretion due to the KCC2-NKCC1 imbalance subsequent to acute oxygen desaturation could result in hyperglycemia in rat pups, paralleling symptoms shown in patients with COVID-19 who experienced acute respiratory distress.

Study of the skin-resorptive effect of a skin antiseptic based on polyvinylpyrollidone-iodineОценка эффективности профилактических дезинфекционных мероприятий на основе комплексного анализа микробиома мест содержания служебных собак

The skin-resorptive effect of a skin antiseptic based on polyvinylpyrollidone-iodine on immature rats of different ages was studied.The skin-resorptive effect of the drug in doses of 5.0 and 0.5 g/kg was revealed on 2–6 week-old rats. The animals showed changes in thyroxine and thyroid-stimulating hormone, as well as general toxic indicators. Absorption of the drug through the skin at a dose of 0.5 g/kg on 4–8 week old rat pups has not been established. The rationale for the use of a skin antiseptic for the hygienic treatment of hands containing PVP-iodine in the age group of children from 8 years old is given. Keywords: toxicity, skin-resorptive effect, immature white rats, skin antiseptic, iodine, thyroxine, thyroid-stimulating hormone.