Necrostatin-1s Suppresses RIPK1-driven Necroptosis and Inflammation in Periventricular Leukomalacia Neonatal Mice.

Periventricular leukomalacia (PVL), a predominant form of brain injury in preterm survivors, is characterized by hypomyelination and microgliosis and is also the major cause of long-term neurobehavioral abnormalities in premature infants. Receptor-interacting protein kinase 1 (RIPK1) plays a pivotal role in mediating cell death and inflammatory signaling cascade. However, very little is known about the potential effect of RIPK1 in PVL and the underlying mechanism. Herein, we found that the expression level of RIPK1 was drastically increased in the brain of PVL neonatal mice models, and treatment of PVL neonatal mice with Necrostatin-1s (Nec-1s), an inhibitor of RIPK1, greatly ameliorated cerebral ischemic injury, exhibiting an increase of body weights, reduction of cerebral infarct size, neuronal loss, and occurrence of necrosis-like cells, and significantly improved the long-term abnormal neurobehaviors of PVL. In addition, Nec-1s significantly suppressed hypomyelination and promoted the differentiation of oligodendrocyte precursor cells (OPCs), as demonstrated by the increased expression levels of MBP and Olig2, the decreased expression level of GPR17, a significant increase in the number of CC-1-positive cells, and suppression of myelin ultrastructure impairment. Moreover, the mechanism of neuroprotective effects of Nec-1s against PVL is closely associated with its suppression of the RIPK1-mediated necrosis signaling molecules, RIPK1, PIPK3, and MLKL. More importantly, inhibition of RIPK1 could reduce microglial inflammatory injury by triggering the M1 to M2 microglial phenotype, appreciably decreasing the levels of M1 marker CD86 and increasing the levels of M2 markers Arg1 or CD206 in PVL mice. Taken together, inhibition of RIPK1 markedly ameliorates the brain injury and long-term neurobehavioral abnormalities of PVL mice through the reduction of neural cell necroptosis and reversing neuroinflammation.

Long-term analysis of adrenocorticotropic hormone monotherapy for infantile epileptic spasms syndrome with periventricular leukomalacia.

PURPOSE: Infantile epileptic spasms syndrome (IESS) with periventricular leukomalacia (PVL) has a poor neurological prognosis. Adrenocorticotropic hormone (ACTH) and vigabatrin therapies are the recommended first-line treatments for IESS. However, ACTH monotherapy for IESS with PVL has not been studied in detail. We analysed long-term outcomes of ACTH monotherapy for IESS with PVL. METHODS: We retrospectively examined 12 patients with IESS and PVL at Saitama Children's Medical Center between January 1993 and September 2022. We evaluated seizure outcomes 3 months post-ACTH therapy and at the last visit. We also assessed electroencephalography findings and developmental outcomes. A positive response was defined as complete remission of epileptic spasms, no other seizure types, and hypsarrhythmia resolution post-ACTH therapy. RESULTS: The median onset age of epileptic spasms was 7 (range: 3-14) months. The median age at initiation of ACTH therapy was 9 (7-17) months. Seven of 12 patients (58.3%) showed a positive response. The median age at the last visit was 5 years and 6 months (1 year and 5 months-22 years and 2 months). At the last visit, only 2 of 7 initial responders remained seizure-free who demonstrated normal electroencephalography findings within 1-month post-ACTH therapy. Patients with epileptic discharge in the parieto-occipital region within 1-month post-ACTH therapy showed relapse of epileptic spasms or other seizure types. CONCLUSION: Patients having epileptic discharge in the parietal or occipital regions on electroencephalography within 1-month post-ACTH therapy may be at a high risk of epileptic spasm recurrence or other seizure types in the long term.

PSB0788 ameliorates maternal inflammation-induced periventricular leukomalacia-like injury.

Studies have shown that periventricular leukomalacia (PVL) is a distinctive form of cerebral white matter injury that pertains to myelination disturbances. Maternal inflammation is a main cause of white matter injury. Intrauterine inflammation cellular will be propagated to the developing brain by the entire maternal-placental-fetal axis, and triggers neural immune injury. As a low-affinity receptor, adenosine A2B receptor (A2BAR) requires high concentrations of adenosine to be significantly activated in pathological conditions. We hypothesized that in the maternal inflammation-induced PVL model, a selective A2BAR antagonist PSB0788 had the potential to prevent the injury. In this work, a total of 18 SD pregnant rats were divided into three groups, and treated with intraperitoneal injection of phosphate buffered saline (PBS), lipopolysaccharide (LPS), or LPS+PSB0788. Placental infection was determined by H&E staining and the inflammatory condition was determined by ELISA. Change of MBP, NG2 and CC-1 in the brain of the rats' offspring were detected by western blot and immunohistochemistry. Furthermore, LPS-induced maternal inflammation reduced the expression of MBP, which related to the decrease in the numbers of OPCs and mature oligodendrocytes in neonate rats. After treatment with PSB0788, the levels of MBP proteins increased in the rats' offspring, improved the remyelination. In conclusion, our study shows that the selective A2BAR antagonist PSB0788 plays an important role in promoting the normal development of OPCs in vivo by the maternal inflammation-induced PVL model. Future studies will focus on the mechanism of PSB0788 in this model.

Pharmacologic Prevention and Treatment of Neonatal Brain Injury.

Neonatal brain injury (NBI) remains a major contributor to neonatal mortality and long-term neurodevelopmental morbidity. Although therapeutic hypothermia is the only proven treatment to minimize brain injury caused by neonatal encephalopathy in term neonates, it provides incomplete neuroprotection. There are no specific drugs yet proven to prevent NBI in preterm neonates. This review discusses the scientific and emerging clinical trial data for several neuroprotective drugs in development, examining potential efficacy and safety concerns. Drugs with the highest likelihood of success and closest to clinical application include erythropoietin for term and preterm neonates and antenatal magnesium for preterm neonates.

Recombinant human erythropoietin offers neuroprotection through inducing endogenous erythropoietin receptor and neuroglobin in a neonatal rat model of periventricular white matter damage.

Recombinant human erythropoietin (rh-EPO) has been reported to have protective effects against brain injury. The purpose of this study was to evaluate the levels of erythropoietin receptor (EPOR) and neuroglobin (Ngb) in a neonatal rat model of periventricular white matter damage (PWMD), and to identify the relationship between the two proteins. On postnatal day 3 (P3), rats underwent permanent ligation of the right common carotid artery followed by 6% O2 for 4h (HI) or sham operation and normoxic exposure (sham). Immediately after HI, rats received a single intraperitoneal injection of rh-EPO (5U/g) or saline. We assessed the expression level of Ngb and EPOR on postnatal days 5, 7, 10 and 14. EPOR in the HI rats was initially increased as compared to the sham rats at P5. Subsequently, EPOR expression decreased, but was maintained at a higher level than in sham rats from P7 to P14. In rh-EPO treated rats, the increase in EPOR was greater than in HI rats at P5. However, EPOR levels decreased sharply from P7 to P14. In HI rats, Ngb was increased compared to the sham rats from P5 to P14. Ngb levels were further upregulated after rh-EPO administration from P5 to P10 compared to HI rats. However, this upregulation decreased at P14. In conclusion, this study shows that EPOR and Ngb were upregulated, and both of them act as important coordinated neuroprotectors in rh-EPO treatment of PWMD. However, the two proteins exhibit different expression patterns.

Immediate neonatal outcomes of preterm infants born to mothers with preterm pre-labour rupture of membranes.

Background & objectives: With the use of early and appropriate use of antibiotics, outcomes have improved in the mother-infant dyads exposed to preterm pre-labour rupture of membranes (PPROM). This study was undertaken to evaluate immediate neonatal outcomes in infants born before 33 completed weeks of gestation to mothers with PPROM versus without PPROM. Methods: During the study period from January 2013 to December 2013, a total of 182 mother-infant dyads were prospectively included in the study. Among the enrolled, 69 were in the PPROM group and 113 in the control group (no PPROM). Mother-infant dyads in PPROM group were covered with antibiotics. The primary outcome was the combined adverse neonatal outcome consisting of sepsis, necrotizing enterocolitis >Stage II or pneumonia or oxygen at day 28 or cystic periventricular leucomalacia or mortality before discharge. Results: Baseline maternal and neonatal variables were comparable across the two groups, except for higher incidence of singletons, maternal pregnancy-induced hypertension (PIH) in the control group and higher proportion of males, complete steroid coverage and oligohydramnios in the PPROM group. The proportion of infants with combined adverse neonatal outcome was similar between the two groups [odds ratio (OR): 1.43; 95% confidence interval (CI): 0.77-2.6]. Both the groups were comparable for most other neonatal morbidities and outcomes, except screen-positive sepsis (OR: 3.7; 95% CI: 1.17-11.5) which was higher in PPROM group. Interpretation & conclusions: Mothers with PPROM and their newborns when treated with timely and appropriate antibiotics had neonatal outcomes similar to those not exposed to PPROM.

Intranasal surfactant protein D as neuroprotective rescue in a neonatal rat model of periventricular leukomalacia.

BACKGROUND: Periventricular leukomalacia (PVL) is the leading cause of neurocognitive deficits in children with prematurity. We previously hypothesized that surfactant protein D (SPD) with its ability to bind toll-like receptors may have a possible ameliorating effect in PVL. METHODS: Three groups were defined as: LPS-administered and postnatal intranasal saline administered group, LPS-administered and postnatal intranasal SPD-treated group, and control group. Twenty-eight offspring rats were reared with their dams until their sacrifice for histological evaluation on day 7. RESULTS: A significant loss of brain weight occurred in the LPS group compared with controls. The postnatal intranasal SPD treatment significantly reduced the number of TUNEL-positive cells in the periventricular white matter as compared with the LPS-treated group. Compared with the control group, LPS injection in the rat brain significantly reduced the MBP-positive staining. Postnatal SPD treatment greatly prevented LPS-stimulated loss of MBP staining. CONCLUSIONS: Present study demonstrated a neuroprotective effect of SPD in a rat model of PVL. Our results offer future implications towards increasing our understanding about multifactorial mechanisms underlying periventricular leukomalacia and developing plausible therapeutic strategies in order to prevent neurocognitive deficits in preterm infants.

Late-onset glucocorticoid-responsive circulatory collapse in preterm infants: clinical characteristics of 14 patients.

Preterm infants may develop acute systemic hypotension that responds to glucocorticoid therapy, but not to volume loading or vasopressors, during the postnatal period. This condition is termed late-onset circulatory collapse (LCC) that develops a few weeks after birth in relatively stable infants. LCC may cause periventricular leukomalacia, periventricular necrosis in the white matter. The aim of this study was to identify the clinical characteristics of LCC. We retrospectively reviewed the clinical data of infants with LCC. Among 41 infants born at < 29 weeks of gestation between 2010 and 2014, we identified 14 infants (median gestational age 25.6 weeks) with LCC. All infants were stable before the acute onset of circulatory collapse at a median age of 21 days, which is characterized by the decreased physical activity, systolic blood pressure (12 mmHg decrease), urine output (76% decrease), and serum sodium level (4 mEq/L decrease), and the increased resistance index in the cerebral and renal arteries on Doppler ultrasonography. Both left ventricular dimension and contraction were well preserved. Three infants developed hyperkalemia. The median time from the initial hydrocortisone dose to improvements was 4 h (interquartile range 3-5 h). Hydrocortisone therapy was effective, but had to be withdrawn slowly to prevent relapse. The median duration of hydrocortisone therapy was 23 days. There was no evidence of periventricular leukomalacia in any of the infants. None of the infants developed adrenal insufficiency during the follow-up period. During the acute stage of LCC, the main priority is the early initiation of glucocorticoid therapy.

Chloride cotransporter NKCC1 inhibitor bumetanide protects against white matter injury in a rodent model of periventricular leukomalacia.

BACKGROUND: Periventricular leukomalacia (PVL) is a major form of preterm brain injury. Na(+)-K(+)-Cl(-) 1 cotransporter (NKCC1) expression on neurons and astrocytes is developmentally regulated and mediates Cl(-) reversal potential. We hypothesized that NKCC1 is highly expressed on oligodendrocytes (OLs) and increases vulnerability to hypoxia-ischemia (HI) mediated white matter injury, and that the NKCC1 inhibitor bumetanide would be protective in a rodent PVL model. METHODS: Immunohistochemistry in Long-Evans rats and PLP-EGFP transgenic mice was used to establish cell-specific expression of NKCC1 in the immature rodent brain. HI was induced on postnatal day 6 (P6) in rats and the protective efficacy of bumetanide (0.3 mg/kg/i.p. q12h × 60 h) established. RESULTS: NKCC1 was expressed on OLs and subplate neurons through the first 2 postnatal weeks, peaking in white matter and the subplate between P3-7. Following HI, NKCC1 is expressed on OLs and neurons. Bumetanide treatment significantly attenuates myelin basic protein loss and neuronal degeneration 7 d post-HI. CONCLUSION: Presence and relative overexpression of NKCC1 in rodent cerebral cortex coincides with a period of developmental vulnerability to HI white matter injury in the immature prenatal brain. The protective efficacy of bumetanide in this model of preterm brain injury suggests that Cl(-) transport is a factor in PVL and that its inhibition may have clinical application in premature human infants.

Treatment with UDP-glucose, GDNF, and memantine promotes SVZ and white matter self-repair by endogenous glial progenitor cells in neonatal rats with ischemic PVL.

Periventricular leukomalacia (PVL) is one of the foremost neurological conditions leading to long-term abnormalities in premature infants. Since it is difficult to prevent initiation of this damage in utero, promoting the innate regenerative potential of the brain after birth may provide a more feasible, prospective therapy for PVL. Treatment with UDP-glucose (UDPG), an endogenous agonist of G protein-coupled receptor 17 (GPR17) that may enhance endogenous self-repair potentiality, glial cell line-derived neurotrophic factor (GDNF), a neurotrophic factor associated with the growth and survival of nerve cells, and memantine, a noncompetitive antagonist of N-methyl-d-aspartate (NMDA) receptors that block ischemia-induced glutamate signal transduction, has been reported to achieve functional, neurological improvement in neonatal rats with PVL. The aim of the present study was to further explore whether UDPG, GDNF and/or memantine could promote corresponding self-repair of the subventricular zone (SVZ) and white matter (WM) in neonatal rats with ischemia-induced PVL. SVZ or WM tissue samples and cultured glial progenitor cells derived from a 5 day-old neonatal rat model of PVL were utilized for studying response to UDPG, GDNF and memantine in vivo and in vitro, respectively. Labeling with 5'-bromo-2'-deoxyuridine and immunofluorescent cell lineage markers after hypoxia-ischemia or oxygen-glucose deprivation (OGD) revealed that UDPG, GDNF and memantine each significantly increased glial progenitor cells and preoligodendrocytes (preOLs), as well as more differentiated immature and mature oligodendrocyte (OL), in both the SVZ and WM in vivo or in vitro. SVZ and WM glial cell apoptosis was also significantly reduced by UDPG, GDNF or memantine, both in vivo and in vitro. These results indicated that UDPG, GDNF or memantine may promote endogenous self-repair by stimulating proliferation of glial progenitor cells derived from both the SVZ and WM, activating their differentiation into more mature OLs, and raising the survival rate of these newly generated glial cells in neonatal rats with ischemic PVL.

Ferrostatins inhibit oxidative lipid damage and cell death in diverse disease models.

Ferrostatin-1 (Fer-1) inhibits ferroptosis, a form of regulated, oxidative, nonapoptotic cell death. We found that Fer-1 inhibited cell death in cellular models of Huntington's disease (HD), periventricular leukomalacia (PVL), and kidney dysfunction; Fer-1 inhibited lipid peroxidation, but not mitochondrial reactive oxygen species formation or lysosomal membrane permeability. We developed a mechanistic model to explain the activity of Fer-1, which guided the development of ferrostatins with improved properties. These studies suggest numerous therapeutic uses for ferrostatins, and that lipid peroxidation mediates diverse disease phenotypes.

Protective effects of pentoxifylline on lipopolysaccharide-induced white matter injury in a rat model of periventricular leukomalasia.

OBJECTIVE: To investigate the potential neuroprotective effect of maternal pentoxifylline (PNTX) treatment in endotoxin-induced periventricular leukomalasia (PVL) in the developing rat brain. METHOD: Intraperitoneal injection of lipopolysaccharide was administered on two of three Wistar pregnant rats to establish PVL. To obtain PNTX-treated group, one of the two dams were injected with PNTX. The control group was treated with saline. Rat pups were grouped as control, maternal LPS-treated group and PNTX + LPS-treated group. At 7th postnatal days, apoptosis and hypomyelination were evaluated. Apoptosis was evaluated by caspase-3 and terminal deoxynucleotidyl transferase [TdT] dUTP nick endlabelling reaction (TUNEL) immunostaining. To assess hypomyelination, myelin basic protein (MBP) staining, as a marker of myelination, was evaluated. RESULTS: MBP staining was significantly less and weaker in the brains of the LPS-treated group as compared with the PNTX-treated group. PNTX treatment significantly reduced the number of apoptotic cells in the periventricular WM shown on Tunel and caspase-3. CONCLUSIONS: Presented study is first indicated that PNTX may provide protection against an LPS-induced inflammatory response and WMI in the developing rat brain. Our results also suggest that PNTX treatment in pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.

Surfactant protein D as a novel therapy for periventricular leukomalacia: is it the missing piece of the puzzle?

Activation of microglia with an inflammatory insult, which plays a central role in periventricular leukomalacia (PVL), results in premyelinating oligodendrocyte death via release of certain cytokines, reactive oxygen and nitrogen species. Toll-like receptor (TLR) 4 is necessary for lipopolysaccharide (LPS) induced oligodenrocyte injury in the CNS. Having an ability to bind TLR 2, 4, and LPS receptor CD14, surfactant protein D (spD) may be a promising agent to counteract the pathways associated with PVL. Supplementation of surfactant treatment with spD may be the key point in prevention of PVL by supression of inflammation and preventing damage to pre-OLs in a vulnerable premature brain operating through TLRs.

[Effect of single or combined application of UDP-glucose, GDNF and memantine on improvement of white matter injury in neonatal rats assessed with light and electron microscopy pathologically].

OBJECTIVE: To evaluate pathologically the effect of the single or combined application of UDP-glucose, GDNF and memantine on the improvement of white matter injury in neonatal rats with periventricular leukomalacia (PVL) under light and electron microscopy. METHODS: A five-day-old neonatal rat model for PVL was established by ligation of the lateral common carotid artery following 120-minute hypoxia. Rats were randomly divided into six groups (30 rats in each group): sham-operated, PVL, UDP-glucose (UDP-glucose 2000 mg/kg intraperitoneally after PVL), GDNF (GDNF 100 µg/kg intracerebrally after PVL), tmemantine (memantine 20 mg/kg intraperitoneally after PVL), and a combination administration of three drugs (UDP-glucose, GDNF and memantine). The rats were sacrificed 7 or 21 days after PVL for assessment of pathological changes in the white matter under both light and electron microscopy. The number and thickness of the myelin sheath in the white matter were measured under electron microscopy, and both of pathological grading and scoring were undertaken under light microscopy. RESULTS: There was rare and sparse myelinogenesis with a loose arrangement of nerve fibers in the white matter under electron microscopy in the PVL group at 7 and 21 days after PVL. The number and thickness of the myelin sheath in the PVL group were significantly less than in the sham-operated, UDP-glucose, GDNF, memantine and combination administration groups (P<0.01). The results of pathological grading of white matter under light microscopy showed that all rats in the PVL group manifested either mild injury (38%-50%) or severe injury (50%-62%) at 7 and 21 days after PVL. The majority of rats (50%-88%) in the four drug administration groups had normal white matter at 7 and 21 days after PVL. The pathological scores at 7 and 21 days after PVL in the PVL group were the highest, and they were significantly higher than in the other five groups (P<0.05). CONCLUSIONS: The single or combined application of UDP-glucose, GDNF and memantine may significantly improve pathological changes in the white matter of rats with PVL. The favorable effect is inferred to be closely correlated with the improvement of brain microenvironment and the enhancement of nerve regeneration promoted by the three drugs.

Neuroprotective effect of neotrofin in a neonatal rat model of periventricular leukomalacia.

Periventricular leukomalacia (PVL) is the dominant form of brain injury in premature infants and no specific treatment is currently available. Neotrofin, a neurotrophin agonist, has been shown to provide neuroprotection in several in vivo and in vitro studies. The aim of this study was to investigate the neuroprotective effect of neotrofin treatment after endotoxin induced PVL in a rat model. Wistar rat pups were divided into four groups as: (1) control, (2) lipopolysaccharide (LPS)-administered group, (3) LPS-administered and prenatal maternal neotrofin-treated group and (4) LPS-administered and postnatal neotrofin-treated group. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) was administered consecutively at the 18th and 19th embryonic days to establish endotoxin-induced PVL model. In the prenatal treatment group dams received an i.p. injection of neotrofin (60 mg/kg) following after the second LPS dose; and in the postnatal treatment group rat pups received i.p. injection of neotrofin (60 mg/kg) at birth. At P7, apoptosis and hypomyelination in periventricular white matter were evaluated by immunohistochemical assessments. The prenatal maternal neotrofin treatment significantly reduced the number of apoptotic cell death and greatly prevented LPS-stimulated loss of hypomyelinization. However, neotrofin treatment in the postnatal period was not as effective as intrauterine treatment. Given our results, neotrofin may be useful in reducing brain injury and possessing clinical relevance for the treatment of white matter injury in newborns.

Erythropoietin-loaded oligochitosan nanoparticles for treatment of periventricular leukomalacia.

In this study, a single intraperitoneal injection of erythropoietin (EPO) loaded oligochitosan nanoparticles (epo-NPs) (average diameter 266 nm) was investigated as a treatment for periventricular leukomalacia (PVL). Nanoparticles were fabricated using a gelation technology process. PVL rats models were prepared to examine the therapeutic efficacy of epo-NPs and analyze the mechanism by which epo-NPs protect white matter. The metabolization of epo-NPs in the liver was also investigated. The pathology and behavioral data show that this single injection of a low quantity of epo-NPs had an excellent therapeutic effect on the rat model of PVL. The EPO release curve in phosphate buffered saline solution was a good fit with the zero-order kinetics distribution and was maintained at around 25% in 48 h. In vivo experiments demonstrated that 50 IU/kg epo-NPs had the same effect as a 5000 IU/kg direct injection of free EPO. Nanoparticles prolonged the time course of EPO metabolization in the liver and the stable release of EPO from the nanoparticles kept the plasma concentration of EPO at around 100 IU/ml during the 8-12h post-injection. Therefore, we suggest that oligochitosan based nanoparticles are an effective vehicle for drug delivery.

[Effects of glial cell line-derived neurotrophic factor and memantine on long-term prognosis in neonatal rats with periventricular leukomalacia].

OBJECTIVE: To evaluate the effects of glial cell line-derived neurotrophic factor (GDNF) and memantine on the long-term prognosis in neonatal rats with ischemia-induced periventricular leukomalacia (PVL). METHODS: Thirty-two 5-day-old neonatal rats were randomly divided into 4 groups: sham-operated, PVL, GDNF-treated and memantine-treated. PVL was induced by right carotid artery ligation and hypoxia in the PVL, GDNF-treated and memantine-treated groups. GDNF (100 µg/kg) or memantine (20 mg/kg) was injected in the two treatment groups immediately after PVL inducement. The weight of the rats was measured immediately before and after hypoxia ischemia (HI). Both of Morris water maze test and Rivlin inclined plane test were performed at 26 days old (21 days after HI). The values of the escape latency (EL) and swimming distance, and the maximum inclined plane degree which the rats could stand at least 5 seconds were compared among the four groups. RESULTS: The lower weight, the prolonged mean values of EL and swimming distance and the reduced maximum inclined plane degree were observed in the PVL group compared to those in the sham-operated, GDNF-treated and memantine-treated groups. There were no significant differences in the weight, the values of EI and swimming distance and the maximum inclined plane degree between the two treatment groups and the sham-operated group. CONCLUSIONS: The administration of either GDNF or memantine can markedly increase the abilities of spatial discrimination,learning and memory, and motor coordination, promote weight gain, and improve long-term prognosis in rats with PVL.

Ibuprofen inhibits neuroinflammation and attenuates white matter damage following hypoxia-ischemia in the immature rodent brain.

Damage to major white matter tracts is a hallmark mark feature of hypoxic-ischemic (HI) brain injury in the preterm neonate. There is, however, no therapeutic intervention to treat this injury. Neuroinflammation is thought to play a prominent role in the pathogenesis of the HI-induced white matter damage but identification of the key mediators that constitute the inflammatory response remain to be fully elucidated. Cyclooxygenase enzymes (COX-1 and COX-2) are candidate neuroinflammatory mediators that may contribute to the HI-induced demise of early oligodendrocyte progenitors and myelination. We investigated whether ibuprofen, a non-steroidal anti-inflammatory drug that inhibits COX enzymes, can attenuate neuroinflammation and associated white matter damage incurred in a rodent model of preterm HI. On postnatal day 3 (P3), HI was produced (right carotid artery ligation and 30 min 6% O(2)). An initial dose of ibuprofen (100mg/kg, s.c.) was administered 2h after HI followed by a maintenance dose (50mg/kg, s.c.) every 24h for 6 days. Post-HI ibuprofen treatment significantly attenuated the P3 HI-induced increases in COX-2 protein expression as well as interleukin-1beta (IL-1ß) and tumour necrosis factor-alpha (TNF-α) levels in the brain. Ibuprofen treatment also prevented the HI-induced loss O4- and O1-positive oligodendrocyte progenitor cells and myelin basic protein (MBP)-positive myelin content one week after P3 HI. These findings suggest that a repeated, daily, ibuprofen treatment regimen administered after an HI insult may be a potential therapeutic intervention to prevent HI-induced damage to white matter progenitors and early myelination in the preterm neonate.

The clinically available NMDA receptor antagonist, memantine, exhibits relative safety in the developing rat brain.

The N-methyl-d-aspartate glutamate receptor (NMDAR) has been implicated in preterm brain injury (periventricular leukomalacia (PVL)) and represents a potential therapeutic target. However, the antagonist dizocilpine (MK-801) has been reported to increase constitutive neuronal apoptosis in the developing rat brain, limiting its clinical use in the developing brain. Memantine is another use-dependent NMDAR antagonist with shorter binding kinetics and has been demonstrated to be protective in a rat model of PVL, without effects on normal myelination or cortical growth. To further evaluate the safety of memantine in the developing brain, we demonstrate here that, in contrast to MK-801, memantine at neuroprotective doses does not increase neuronal constitutive apoptosis. In addition, there are no long-term alterations in the expression of NMDAR subunits, AMPAR subunits, and two markers of synaptogenesis, Synapsin-1 and PSD95. Evaluating clinically approved drugs in preclinical neonatal animal models of early brain development is an important prerequisite to considering them for clinical trial in preterm infants and early childhood.