Neonatal exposure to phenobarbital potentiates schizophrenia-like behavioral outcomes in the rat

Comparison of the effect of phenobarbital & levetiracetam in the treatment of neonatal abstinence syndrome (NAS) as adjuvant treatment in neonates admitted to the neonatal intensive care unit: a randomized clinical trial

BACKGROUND

Infants who are born from mothers with substance use disorder might suffer from neonatal abstinence syndrome (NAS) and need treatment with medicines. One of these medicines is phenobarbital, which may cause side effects in long-term consumption. Alternative drugs can be used to reduce these side effects. This study seeks the comparison of the effects of phenobarbital & levetiracetam as adjuvant therapy in neonatal abstinence syndrome.

METHODS

This randomized clinical trial was performed in one year from May 2021 until May 2022. The neonates who were born from mothers with substance use disorder and had neonatal abstinence syndrome in Afzalipoor Hospital of Kerman were studied. The treatment started with morphine initially and every four hours the infants were checked. The infants who were diagnosed with uncontrolled symptoms After obtaining informed consent from the parents were randomly divided into two groups and treated with secondary drugs, either phenobarbital or levetiracetam.

RESULTS

Based on the obtained results, it was clear that there was no significant difference between the hospitalization time of the two infant groups under therapy (phenobarbital: 18.59 days versus Levetiracetam 18.24 days) (P-value = 0.512). Also, there was no significant difference between both groups in terms of the frequency of re-hospitalization during the first week after discharge, the occurrence of complications, and third treatment line prescription (P-value = 0.644).

CONCLUSIONS

Based on the obtained results, like hospitalization duration time (P-value = 0.512) it seems that levetiracetam can be used to substitute phenobarbital in treating neonatal abstinence syndrome.

TRIAL REGISTRATION

The current study has been registered in the Iran registry of clinical trials website (fa.irct.ir) on the date 25/2/2022 with registration no. IRCT20211218053444N2.

Early life phenobarbital exposure dysregulates the hippocampal transcriptome

Introduction: Phenobarbital (PB) and levetiracetam (LEV) are the first-line therapies for neonates with diagnosed seizures, however, a growing body of evidence shows that these drugs given during critical developmental windows trigger lasting molecular changes in the brain. While the targets and mechanism of action of these drugs are well understood-what is not known is how these drugs alter the transcriptomic landscape, and therefore molecular profile/gene expression during these critical windows of neurodevelopment. PB is associated with a range of neurotoxic effects in developing animals, from cell death to altered synaptic development to lasting behavioral impairment. LEV does not produce these effects. Methods: Here we evaluated the effects of PB and Lev on the hippocampal transcriptome by RNA sequencing. Neonatal rat pups were given a single dose of PB, Lev or vehicle and sacrificed 72 h later-at time at which drug is expected to be cleared. Results: We found PB induces broad changes in the transcriptomic profile (124 differentially expressed transcripts), as compared to relatively small changes in LEV-treated animals (15 transcripts). PB exposure decreased GABAergic and oligodendrocyte markers pvalb and opalin, and increased the marker of activated microglia, cd68 and the astrocyte- associated gene vegfa. These data are consistent with the existing literature showing developmental neurotoxicity associated with PB, but not LEV. Discussion: The widespread change in gene expression after PB, which affected transcripts reflective of multiple cell types, may provide a link between acute drug administration and lasting drug toxicity.

Anti-seizure medication-induced developmental cell death in neonatal rats is unaltered by history of hypoxia

BACKGROUND

Many anti-seizure medications (ASMs) trigger neuronal cell death when administered during a confined period of early life in rodents. Prototypical ASMs used to treat early-life seizures such as phenobarbital induce this effect, whereas levetiracetam does not. However, most prior studies have examined the effect of ASMs in naïve animals, and the degree to which underlying brain injury interacts with these drugs to modify cell death is poorly studied. Moreover, the degree to which drug-induced neuronal cell death differs as a function of sex is unknown.

METHODS

We treated postnatal day 7 Sprague Dawley rat pups with vehicle, phenobarbital (75 mg/kg) or levetiracetam (200 mg/kg). Separate groups of pups were pre-exposed to either normoxia or graded global hypoxia. Separate groups of males and females were used. Twenty-four hours after drug treatment, brains were collected and processed for markers of cell death.

RESULTS

Consistent with prior studies, phenobarbital, but not levetiracetam, increased cell death in cortical regions, basal ganglia, hippocampus, septum, and lateral thalamus. Hypoxia did not modify basal levels of cell death. Females - collapsed across treatment and hypoxia status, displayed a small but significant increase in cell death as compared to males in the cingulate cortex, somatosensory cortex, and the CA1 and CA3 hippocampus; these effects were not modulated by hypoxia or drug treatment.

CONCLUSION

We found that a history of graded global hypoxia does not alter the neurotoxic profile of phenobarbital. Levetiracetam, which does not induce cell death in normal developing animals, maintained a benign profile on the background of neonatal hypoxia. We found a sex-based difference, as female animals showed elevated levels of cell death across all treatment conditions. Together, these data address several long-standing gaps in our understanding of the neurotoxic profile of antiseizure medications during early postnatal development.

Phenobarbital does not worsen outcomes of neonatal hypoxia on hippocampal LTP on rats

Introduction

Neonatal hypoxia is a common cause of early-life seizures. Both hypoxia-induced seizures (HS), and the drugs used to treat them (e.g., phenobarbital, PB), have been reported to have long-lasting impacts on brain development. For example, in neonatal rodents, HS reduces hippocampal long-term potentiation (LTP), while PB exposure disrupts GABAergic synaptic maturation in the hippocampus. Prior studies have examined the impact of HS and drug treatment separately, but in the clinic, PB is unlikely to be given to neonates without seizures, and neonates with seizures are very likely to receive PB. To address this gap, we assessed the combined and separate impacts of neonatal HS and PB treatment on the development of hippocampal LTP.

Methods

Male and female postnatal day (P)7 rat pups were subjected to graded global hypoxia (or normoxia as a control) and treated with either PB (or vehicle as a control). On P13-14 (P13+) or P29-37 (P29+), we recorded LTP of the Schaffer collaterals into CA1 pyramidal layer in acute hippocampal slices. We compared responses to theta burst stimulation (TBS) and tetanization induction protocols.

Results

Under the TBS induction protocol, female rats showed an LTP impairment caused by HS, which appeared only at P29+. This impairment was delayed compared to male rats. While LTP in HS males was impaired at P13+, it normalized by P29+. Under the tetanization protocol, hypoxia produced larger LTP in males compared to female rats. PB injection, under TBS, did not exacerbate the effects of hypoxia. However, with the tetanization protocol, PB - on the background of HS - compensated for these effects, returning LTP to control levels.

Discussion

These results point to different susceptibility to hypoxia as a function of sex and age, and a non-detrimental effect of PB when administered after hypoxic seizures.

Efficacy of the anti-seizure medications in acute symptomatic neonatal seizures caused by stroke. A systematic review

BACKGROUND AND AIM

Neonatal stroke is the second cause of acute symptomatic neonatal seizures after hypoxic-ischemic encephalopathy. The aim of this systematic review is to determine which drug among those available represents the best therapeutic choice for treatment of secondary seizures due to neonatal stroke.

METHODS

We performed a systematic review searching on PubMed the keywords "Neonatal", "Stroke", "Seizures" and "Treatment". Search was limited only to English language with no time limit. Last literature search was done on May 30, 2022.

RESULTS

We selected 5 articles involving a total of 52 full-term neonates. In 96.1% the first line treatment was phenobarbital and in 3.9% was used phenobarbital associated with midazolam from the seizure onset but in all of these cases it was necessary to introduce further medications for controlling the seizures. As second line treatment was used lidocaine (response rate of 53.3%), midazolam (response rate of 15.38%) bumetanide (response rate of 100%), and fosphenytoin (no response). As third line treatment was used lidocaine (response rate of 87.5%), Midazolam (response rate of 60%), levetiracetam and clonazepam (response rate of 100%).

CONCLUSIONS

Our review shows that the use of ASMs that act throughout a gabaergic mechanism are inadequate in controlling seizures secondary to neonatal stroke in full-term newborns. Very effective seems to be lidocaine and levetiracetam with an apparent safer profile in short and long term. Bumetanide shows promising results, but they need to be confirmed by phase 3 studies.

The GluN2B-Selective Antagonist Ro 25-6981 Is Effective against PTZ-Induced Seizures and Safe for Further Development in Infantile Rats

The GluN2B subunit of NMDA receptors represents a perspective therapeutic target in various CNS pathologies, including epilepsy. Because of its predominant expression in the immature brain, selective GluN2B antagonists are expected to be more effective early in postnatal development. The aim of this study was to identify age-dependent differences in the anticonvulsant activity of the GluN2B-selective antagonist Ro 25-6981 and assess the safety of this drug for the developing brain. Anticonvulsant activity of Ro 25-6981 (1, 3, and 10 mg/kg) was tested in a pentylenetetrazol (PTZ) model in infantile (12-day-old, P12) and juvenile (25-day-old, P25) rats. Ro 25-6981 (1 or 3 mg/kg/day) was administered from P7 till P11 to assess safety for the developing brain. Animals were then tested repeatedly in a battery of behavioral tests focusing on sensorimotor development, cognition, and emotionality till adulthood. Effects of early exposure to Ro 25-6981 on later seizure susceptibility were tested in the PTZ model. Ro 25-6981 was effective against PTZ-induced seizures in infantile rats, specifically suppressing the tonic phase of the generalized tonic-clonic seizures, but it failed in juveniles. Neither sensorimotor development nor cognitive abilities and emotionality were affected by early-life exposure to Ro 25-6981. Treatment cessation did not affect later seizure susceptibility. Our data are in line with the maturational gradient of the GluN2B-subunit of NMDA receptors and demonstrate developmental differences in the anti-seizure activity of the GluN2B-selective antagonist and its safety for the developing brain.

Project Console: a quality improvement initiative for neonatal abstinence syndrome in a children's hospital level IV neonatal intensive care unit

Objective

To improve care for infants with neonatal abstinence syndrome.

Design

Infants with a gestational age of ≥35 weeks with prenatal opioid exposure were eligible for our quality improvement initiative. Interventions in our Plan–Do–Study–Act cycles included physician consensus, re-emphasis on non-pharmacological treatment, the Eat Sleep Console method to measure functional impairment, morphine as needed, clonidine and alternative soothing methods for parental unavailability (volunteer cuddlers and automated sleeper beds). Pre-intervention and post-intervention outcomes were compared.

Results

Length of stay decreased from 31.8 to 10.5 days (p<0.0001) without an increase in readmissions. Composite pharmacotherapy exposure days decreased from 28.7 to 5.5 (p<0.0001). This included reductions in both morphine exposure days (p<0.0001) and clonidine exposure days (p=0.01). Fewer infants required pharmacotherapy (p=0.02).

Conclusions

Our study demonstrates how a comprehensive initiative can improve care for infants with neonatal abstinence syndrome in an open-bay or a high-acuity neonatal intensive care unit when rooming-in is not available or other comorbidities are present.

Treating the symptom or treating the disease in neonatal seizures: a systematic review of the literature

Aim

The existing treatment options for neonatal seizures have expanded over the last few decades, but no consensus has been reached regarding the optimal therapeutic protocols. We systematically reviewed the available literature examining neonatal seizure treatments to clarify which drugs are the most effective for the treatment of specific neurologic disorders in newborns.

Method

We reviewed all available, published, literature, identified using PubMed (published between August 1949 and November 2020), that focused on the pharmacological treatment of electroencephalogram (EEG)-confirmed neonatal seizures.

Results

Our search identified 427 articles, of which 67 were included in this review. Current knowledge allowed us to highlight the good clinical and electrographic responses of genetic early-onset epilepsies to sodium channel blockers and the overall good response to levetiracetam, whose administration has also been demonstrated to be safe in both full-term and preterm newborns.

Interpretation

Our work contributes by confirming the limited availability of evidence that can be used to guide the use of anticonvulsants to treat newborns in clinical practice and examining the efficacy and potentially harmful side effects of currently available drugs when used to treat the developing newborn brain; therefore, our work might also serve as a clinical reference for future studies.

Impact of maternal medication for opioid use disorder on neurodevelopmental outcomes of infants treated for neonatal opioid withdrawal syndrome

BACKGROUND

Increasing rates of maternal opioid use disorder has led to greater number of opioid exposed newborns (OENs). Maternal enrollment in medication for opioid use disorder (MOUD) program improves short term neonatal outcomes. This study aimed at assessing neurobehavioral outcomes for OENs.

METHODS

Retrospective observational cohort study of OENs between Jul 2006 and Dec 2018. Two study groups were identified as initiation of medication for opioid use disorder (MOUD) prior to diagnoses of pregnancy or after. Primary outcome variables were enrollment in and duration of EI services. Secondary outcome variable was diagnoses of a behavioral and/or developmental disorder (BDD) during the study period.

RESULTS

Of 242 infants, 113 were enrolled in EI and BDD diagnoses data was available for all infants [age range 6 to 12 years], 82% infants had exposure to maternal MOUD, while 18% were exposed to either maternal prescription non-MOUD opioids or illicit opioids. Maternal MOUD initiation prior to pregnancy was associated with improved short term outcomes for OENs. Almost a third of infants were diagnosed with a BDD with no differences between the two study groups.

CONCLUSION

Early initiation of maternal MOUD improved short term outcomes and discharge disposition for OENs. Prolonged in-utero exposure to opioids presents a potential for negative impact on neurodevelopmental and behavioral outcomes. These risks must be considered to increase access and adherence to EI services, as well as to focus on non-opioid based maternal MOUD. Longitudinal studies assessing the safety of MOUD on short and long-term child health outcomes are needed.

Cerebrolysin enhances the expression of the synaptogenic protein LRRTM4 in the hippocampus and improves learning and memory in senescent rats

Aging reduces the efficiency of the organs and systems, including the cognitive functions. Brain aging is related to a decrease in the vascularity, neurogenesis, and synaptic plasticity. Cerebrolysin, a peptide and amino acid preparation, has been shown to improve the cognitive performance in animal models of Alzheimer's disease. Similarly, the leucine-rich repeat transmembrane 4 protein exhibits a strong synaptogenic activity in the hippocampal synapses. The aim of this study was to evaluate the effect of the cerebrolysin treatment on the learning and memory abilities, sensorimotor functions, and the leucine-rich repeat transmembrane 4 protein expression in the brain of 15-month-old rats. Cerebrolysin (1076 mg/kg) or vehicle was administered to Wistar rats intraperitoneally for 4 weeks. After the treatments, learning and memory were tested using the Barnes maze test, and the acoustic startle response, and its pre-pulse inhibition and habituation were measured. Finally, the leucine-rich repeat transmembrane 4 expression was measured in the brainstem, striatum, and hippocampus using a Western-blot assay. The 15-month-old vehicle-treated rats showed impairments in the habituation of the acoustic startle response and in learning and memory when compared to 3-month-old rats. These impairments were attenuated by the subchronic cerebrolysin treatment. The leucine-rich repeat transmembrane 4 protein expression was lower in the old vehicle-treated rats than in the young rats; the cerebrolysin treatment attenuated that decrease in the old rats. The leucine-rich repeat transmembrane 4 protein was not expressed in striatum or brainstem. These results suggest that the subchronic cerebrolysin treatment enhances the learning and memory abilities in aging by increasing the expression of the leucine-rich repeat transmembrane 4 protein in the hippocampus.

FTY720 administration following hypoxia-induced neonatal seizure reverse cognitive impairments and severity of seizures in male and female adult rats: The role of inflammation

Hypoxia-induced neonatal seizure mainly leads to deleterious effects on brain function, especially cognitive impairments and increased susceptibility to epilepsy later in life. Early inflammation plays an important role in the pathology of these consequences. Therefore, we explored the long-term outcomes of Fingolimod treatment as an anti-inflammatory and neuroprotective agent in a rat model of HINS. Seizures were induced in rats (postnatal day 10) by 5% O2 exposure for 15 min. Sixty minutes after the onset of hypoxia, pups received FTY720 (0.3 mg.kg-1) or normal saline for 12 consecutive days (lactation period), and they were used at P60-P63 for behavioral tests, ELISA and Pentylenetetrazole kindling model. The results of open field, novel object recognition and elevated plus maze tasks showed that Fingolimod prevents hippocampal memory dysfunction and anxiety-like behavior in both male and female hypoxic groups, which was accompanied with decreased TNF-α level in hippocampus. In addition, FTY720 postponed epileptogenesis just in female hypoxic + FTY group and decreased severity of seizures in both genders. Our results suggest that, FTY720 treatment in immature rats, which were previously subjected to HINS, prevented the long-lasting deficits, like cognitive impairments, decreased the severity of seizures and related inflammation. In addition, FTY720 did not show significant interaction with gender in most of the experiments, except the average day to reach fully kindled state. Taken together, FTY720 has therapeutic potential for long lasting effects of HINS in both male and female animals at puberty.

Seizures in the neonate: A review of etiologies and outcomes

Neonatal seizures occur in their majority in close temporal relation to an acute brain injury or systemic insult, and are accordingly defined as acute symptomatic or provoked seizures. However less frequently, unprovoked seizures may also present in the neonatal period as secondary to structural brain abnormalities, thus corresponding to structural epilepsies, or to genetic conditions, thus corresponding to genetic epilepsies. Unprovoked neonatal seizures should be thus considered as the clinical manifestation of early onset structural or genetic epilepsies that often have the characteristics of early onset epileptic encephalopathies. In this review, we address the conundrum of neonatal seizures including acute symptomatic, remote symptomatic, provoked, and unprovoked seizures, evolving to post-neonatal epilepsies, and neonatal onset epilepsies. The different clinical scenarios involving neonatal seizures, each with their distinct post-neonatal evolution are presented. The structural and functional impact of neonatal seizures on brain development and the concept of secondary epileptogenesis, with or without a following latent period after the acute seizures, are addressed. Finally, we underline the need for an early differential diagnosis between an acute symptomatic seizure and an unprovoked seizure, since it is associated with fundamental differences in clinical evolution. These are crucial aspects for neonatal management, counselling and prognostication. In view of the above aspects, we provide an outlook on future strategies and potential lines of research in this field.

Perinatal Brain Injury and Inflammation: Lessons from Experimental Murine Models

Perinatal brain injury or neonatal encephalopathy (NE) is a state of disturbed neurological function in neonates, caused by a number of different aetiologies. The most prominent cause of NE is hypoxic ischaemic encephalopathy, which can often induce seizures. NE and neonatal seizures are both associated with poor neurological outcomes, resulting in conditions such as cerebral palsy, epilepsy, autism, schizophrenia and intellectual disability. The current treatment strategies for NE and neonatal seizures have suboptimal success in effectively treating neonates. Therapeutic hypothermia is currently used to treat NE and has been shown to reduce morbidity and has neuroprotective effects. However, its success varies between developed and developing countries, most likely as a result of lack of sufficient resources. The first-line pharmacological treatment for NE is phenobarbital, followed by phenytoin, fosphenytoin and lidocaine as second-line treatments. While these drugs are mostly effective at halting seizure activity, they are associated with long-lasting adverse neurological effects on development. Over the last years, inflammation has been recognized as a trigger of NE and seizures, and evidence has indicated that this inflammation plays a role in the long-term neuronal damage experienced by survivors. Researchers are therefore investigating the possible neuroprotective effects that could be achieved by using anti-inflammatory drugs in the treatment of NE. In this review we will highlight the current knowledge of the inflammatory response after perinatal brain injury and what we can learn from animal models.

Clonidine versus phenobarbital as adjunctive therapy for neonatal abstinence syndrome

OBJECTIVE

To compare clonidine versus phenobarbital as adjunctive therapy in infants who failed monotherapy with morphine for neonatal abstinence syndrome (NAS).

STUDY DESIGN

Prospective, randomized, open-label study of infants ≥ 35 weeks' gestation. Infants received clonidine or phenobarbital per protocol. Primary outcome was morphine treatment days. Secondary outcomes were inpatient adjunctive days, length of stay (LOS), triple therapy, safety, and readmission rates.

RESULTS

A total of 25 infants were treated with clonidine (n = 14) or phenobarbital (n = 11). Mean morphine treatment duration was significantly longer with clonidine (34.4 days, SD = 10.6) compared with phenobarbital (25.5 days, SD = 7.3, p = 0.026). The clonidine group also had higher inpatient adjunctive days (mean: 33.8 days [SD = 14.3] vs. 22 days [SD = 12.6], p = 0.042) and LOS (mean: 41.8 days [SD = 10.9] vs. 31 days [SD = 10]; p = 0.018) compared with phenobarbital.

CONCLUSIONS

Phenobarbital, as adjunctive therapy, led to significantly shorter duration of morphine therapy, inpatient adjunctive days, and length of stay compared with clonidine.

Short-Term Neurodevelopmental Outcome in Term Neonates Treated with Phenobarbital versus Levetiracetam: A Single-Center Experience

Background

Phenobarbital (PB) has been traditionally used as the first-line treatment for neonatal seizures. More recently, levetiracetam (LEV) has been increasingly used as a promising newer antiepileptic medication for treatment of seizures in neonates.

Objectives

The aim of our study was to compare the effect of PB vs. LEV on short-term neurodevelopmental outcome in infants treated for neonatal seizures.

Method

This randomized, one-blind prospective study was conducted on term neonates admitted to the Neonatal Intensive Care Unit of S. Bambino Hospital, University Hospital "Policlinico-Vittorio Emanuele," Catania, Italy, from February 2016 to February 2018. Thirty term neonates with seizures were randomized to receive PB or LEV; the Hammersmith Neonatal Neurological Examination (HNNE) was used at baseline (T0) and again one month after the initial treatment (T1).

Results

We found a significantly positive HNNE score for the developmental outcomes, specifically tone and posture, in neonates treated with LEV. There was no significant improvement in the HNNE score at T1 in the neonates treated with PB.

Conclusion

This study suggests a positive effect of levetiracetam on tone and posture in term newborns treated for neonatal seizures. If future randomized-controlled studies also show better efficacy of LEV in the treatment of neonatal seizures, LEV might potentially be considered as the first-line anticonvulsant in this age group.

Microglia in the developing prefrontal cortex of rats show dynamic changes following neonatal disconnection of the ventral hippocampus

Impaired ventral hippocampal (VH)-prefrontal cortex (PFC) connectivity is implicated in many cognitive and behavioral disorders. Excitotoxic neonatal VH (nVH) lesion in rat pups has been shown to induce synaptic pruning in the PFC as well as behavioral changes of relevance to developmental neuropsychiatric disorders. In the current study, we hypothesized that microglia, immune cells required for proper brain development and plasticity, may play a role in the development of abnormal behaviors in the nVH-lesioned animals. Ibotenic acid-induced nVH lesion was induced in postnatal day (P)7 male rats. Developmental changes in microglial density, morphology, ultrastructure and gene expression were analyzed in the PFC at P20 and P60. Our results revealed increased microglial reactivity and phagocytic activity in the lesioned rats at P20. Increased mRNA levels of C3 and C1q, complement molecules involved in synaptic pruning, were concomitantly observed. Diminished, but maintained, microglial reactivity and reduced antioxidative defenses were identified in lesioned rats at P60. Behavioral deficits were significantly reduced in the post-pubertal rats by suppressing microglial reactivity by a one-week minocycline treatment immediately after the lesion, These results suggest that early-life disconnection of the VH has long-lasting consequences for microglial functions in the connected structures. Alterations in microglia may underlie synaptic reorganization and behavioral deficits observed following neonatal VH disconnection.

MMP-1 overexpression selectively alters inhibition in D1 spiny projection neurons in the mouse nucleus accumbens core

Protease activated receptor-1 (PAR-1) and its ligand, matrix metalloproteinase-1 (MMP-1), are altered in several neurodegenerative diseases. PAR-1/MMP-1 signaling impacts neuronal activity in various brain regions, but their role in regulating synaptic physiology in the ventral striatum, which is implicated in motor function, is unknown. The ventral striatum contains two populations of GABAergic spiny projection neurons, D1 and D2 SPNs, which differ with respect to both synaptic inputs and projection targets. To evaluate the role of MMP-1/PAR-1 signaling in the regulation of ventral striatal synaptic function, we performed whole-cell recordings (WCR) from D1 and D2 SPNs in control mice, mice that overexpress MMP-1 (MMP-1OE), and MMP-1OE mice lacking PAR-1 (MMP-1OE/PAR-1KO). WCRs from MMP1-OE mice revealed an increase in spontaneous inhibitory post-synaptic current (sIPSC), miniature IPSC, and miniature excitatory PSC frequency in D1 SPNs but not D2 SPNs. This alteration may be partially PAR-1 dependent, as it was not present in MMP-1OE/PAR-1KO mice. Morphological reconstruction of D1 SPNs revealed increased dendritic complexity in the MMP-1OE, but not MMP-1OE/PAR-1KO mice. Moreover, MMP-1OE mice exhibited blunted locomotor responses to amphetamine, a phenotype also observed in MMP-1OE/PAR-1KO mice. Our data suggest PAR-1 dependent and independent MMP-1 signaling may lead to alterations in striatal neuronal function.

Role of Prefrontal Cortex Anti- and Pro-inflammatory Cytokines in the Development of Abnormal Behaviors Induced by Disconnection of the Ventral Hippocampus in Neonate Rats

Neonatal disconnection of ventral hippocampus (VH) outputs in rats has been reported to lead to post-pubertal behavioral and synaptic changes of relevance to schizophrenia. Increased oxidative and inflammatory load in the prefrontal cortex (PFC) has been suggested to mediate some of the effects of neonatal VH lesion (NVHL). In this study, we hypothesized that developmental imbalance of anti- and pro-inflammatory factors within the PFC might affect synaptic development thus contributing to the adult NVHL-induced behavioral deficits. Ibotenic acid-induced excitotoxic NVHL was performed in postnatal day (PD) 7 male Sprague-Dawley rats and the mRNA levels of select pro- and anti-inflammatory cytokines were measured in the medial PFC (mPFC) at two developmental time points (PD15 and PD60). We observed a development-specific increase of pro-inflammatory cytokine, interleukin (IL)-1β mRNA at PD15, and an overall reduction in the expression and signaling of transforming growth factor beta 1 (TGF-β1), an anti-inflammatory cytokine, at both PD15 and PD60 in the NVHL animals. These cytokine changes were not seen in the somatosensory cortex (SSC) or tissue surrounding the lesion site. Daily administration of systemic recombinant TGF-β1 from PD7-14 prevented the appearance of hyperlocomotion, deficits in prepulse inhibition (PPI) of startle and social interaction (SI) in post-pubertal (PD60) NVHL rats. Neonatal supplementation of TGF-β1 was also able to attenuate dendritic spine loss in the layer 3 mPFC pyramidal neurons of NVHL animals. These results suggest that early damage of the VH has long-lasting inflammatory consequences in distant connected structures, and that TGF-β1 has potential to confer protection against the deleterious effects of developmental hippocampal damage.

Complex spectrum of phenobarbital effects in a mouse model of neonatal hypoxia-induced seizures

Seizures in neonates, mainly caused by hypoxic-ischemic encephalopathy, are thought to be harmful to the brain. Phenobarbital remains the first line drug therapy for the treatment of suspected neonatal seizures but concerns remain with efficacy and safety. Here we explored the short- and long-term outcomes of phenobarbital treatment in a mouse model of hypoxia-induced neonatal seizures. Seizures were induced in P7 mice by exposure to 5% O₂ for 15 minutes. Immediately after hypoxia, pups received a single dose of phenobarbital (25 mg.kg^-1) or saline. We observed that after administration of phenobarbital seizure burden and number of seizures were reduced compared to the hypoxic period; however, PhB did not suppress acute histopathology. Behavioural analysis of mice at 5 weeks of age previously subjected to hypoxia-seizures revealed an increase in anxiety-like behaviour and impaired memory function compared to control littermates, and these effects were not normalized by phenobarbital. In a seizure susceptibility test, pups previously exposed to hypoxia, with or without phenobarbital, developed longer and more severe seizures in response to kainic acid injection compared to control mice. Unexpectedly, mice treated with phenobarbital developed less hippocampal damage after kainic acid than untreated counterparts. The present study suggests phenobarbital treatment in immature mice does not improve the long lasting functional deficits induces by hypoxia-induced seizures but, unexpectedly, may reduce neuronal death caused by exposure to a second seizure event in later life.

Genetically Epilepsy-Prone Rats Display Anxiety-Like Behaviors and Neuropsychiatric Comorbidities of Epilepsy

Epilepsy is associated with a variety of neuropsychiatric comorbidities, including both anxiety and depression. Despite high occurrences of depression and anxiety seen in human epilepsy populations, little is known about the etiology of these comorbidities. Experimental models of epilepsy provide a platform to disentangle the contribution of acute seizures, genetic predisposition, and underlying circuit pathologies to anxious and depressive phenotypes. Most studies to date have focused on comorbidities in acquired epilepsies; genetic models, however, allow for the assessment of affective phenotypes that occur prior to onset of recurrent seizures. Here, we tested male and female genetically epilepsy-prone rats (GEPR-3s) and Sprague-Dawley controls in a battery of tests sensitive to anxiety-like and depressive-like phenotypes. GEPR-3s showed increased anxiety-like behavior in the open field test, elevated plus maze, light-dark transition test, and looming threat test. Moreover, GEPR-3s showed impaired prepulse inhibition of the acoustic startle reflex, decreased sucrose preference index, and impaired novel object recognition memory. We also characterized defense behaviors in response to stimulation thresholds of deep and intermediate layers of the superior colliculus (DLSC), but found no difference between strains. In sum, GEPR-3s showed inherited anxiety, an effect that did not differ significantly between sexes. The anxiety phenotype in adult GEPR-3s suggests strong genetic influences that may underlie both the seizure disorder and the comorbidities seen in epilepsy.

Ursodeoxycholic acid versus phenobarbital for cholestasis in the Neonatal Intensive Care Unit

Background

Although neonates and young infants with cholestasis are commonly treated with either phenobarbital or ursodeoxycholic acid (ursodiol), there is no evidence that phenobarbital is effective for this indication. Our objective was to compare the effectiveness of ursodiol and phenobarbital for the treatment of cholestasis in a diverse NICU population.

Methods

This is a retrospective cohort study including infants with cholestasis who were admitted to a Level IV NICU between January 2010 and December 2015. Drug courses of phenobarbital and ursodiol were identified within the medical record, and medical, demographic, and drug information were extracted. The primary outcome was reduction in direct bilirubin.

Results

Sixty-eight infants provided a total of 112 courses of drug therapy for comparison. Diverse medical diagnoses were captured in the patient cohort. Ursodiol was significantly more effective in reducing direct bilirubin than was phenobarbital (− 1.89 vs + 0.76 mg/dL; − 33.33 vs + 13.0 umol/L, p-value 0.03), even after controlling for baseline cholestasis severity, intrauterine growth restriction status, and lipid lowering therapy (− 2.16 vs + 0.27 mg/dl; − 36.94 vs + 4.62 umol/L, p-value 0.03). There was no improvement in direct bilirubin in the majority of infants treated with phenobarbital.

Conclusions

Phenobarbital, as compared to ursodiol, has limited efficacy for the reduction of direct bilirubin in neonates and young infants with cholestasis. Given new data regarding the potential neurotoxicity of phenobarbital in the developing brain, providers may choose to avoid phenobarbital in the treatment of cholestasis in infants.

Neonatal phenobarbital exposure disrupts GABAergic synaptic maturation in rat CA1 neurons

OBJECTIVE

Phenobarbital is the most commonly utilized drug for the treatment of neonatal seizures. The use of phenobarbital continues despite growing evidence that it exerts suboptimal seizure control and is associated with long-term alterations in brain structure, function, and behavior. Alterations following neonatal phenobarbital exposure include acute induction of neuronal apoptosis, disruption of synaptic development in the striatum, and a host of behavioral deficits. These behavioral deficits include those in learning and memory mediated by the hippocampus. However, the synaptic changes caused by acute exposure to phenobarbital that lead to lasting effects on brain function and behavior remain understudied.

METHODS

Postnatal day (P)7 rat pups were treated with phenobarbital (75 mg/kg) or saline. On P13-14 or P29-37, acute slices were prepared and whole-cell patch-clamp recordings were made from CA1 pyramidal neurons.

RESULTS

At P14 we found an increase in miniature inhibitory postsynaptic current (mIPSC) frequency in the phenobarbital-exposed as compared to the saline-exposed group. In addition to this change in mIPSC frequency, the phenobarbital group displayed larger bicuculline-sensitive tonic currents, decreased capacitance and membrane time constant, and a surprising persistence of giant depolarizing potentials. At P29+, the frequency of mIPSCs in the saline-exposed group had increased significantly from the frequency at P14, typical of normal synaptic development; at this age the phenobarbital-exposed group displayed a lower mIPSC frequency than did the control group. Spontaneous inhibitory postsynaptic current (sIPSC) frequency was unaffected at either P14 or P29+.

SIGNIFICANCE

These neurophysiological alterations following phenobarbital exposure provide a potential mechanism by which acute phenobarbital exposure can have a long-lasting impact on brain development and behavior.

Comparison of the long-term behavioral effects of neonatal exposure to retigabine or phenobarbital in rats

Anticonvulsant drugs, when given during vulnerable periods of brain development, can have long-lasting consequences on nervous system function. In rats, the second postnatal week approximately corresponds to the late third trimester of gestation/early infancy in humans. Exposure to phenobarbital during this period has been associated with deficits in learning and memory, anxiety-like behavior, and social behavior, among other domains. Phenobarbital is the most common anticonvulsant drug used in neonatology. Several other drugs, such as lamotrigine, phenytoin, and clonazepam, have also been reported to trigger behavioral changes. A new generation anticonvulsant drug, retigabine, has not previously been evaluated for long-term effects on behavior. Retigabine acts as an activator of KCNQ channels, a mechanism that is unique among anticonvulsants. Here, we examined the effects retigabine exposure from postnatal day (P)7 to P14 on behavior in adult rats. We compared these effects with those produced by phenobarbital (as a positive control) and saline (as a negative control). Motor behavior was assessed by using the open field and rotarod, anxiety-like behavior by the open field, elevated plus maze, and light-dark transition task, and learning/memory by the passive avoidance task; social interactions were assessed in same-treatment pairs, and nociceptive sensitivity was assessed via the tail-flick assay. Motor behavior was unaltered by exposure to either drug. We found that retigabine exposure and phenobarbital exposure both induced increased anxiety-like behavior in adult animals. Phenobarbital, but not retigabine, exposure impaired learning and memory. These drugs also differed in their effects on social behavior, with retigabine-exposed animals displaying greater social interaction than phenobarbital-exposed animals. These results indicate that neonatal retigabine induces a subset of behavioral alterations previously described for other anticonvulsant drugs and extend our knowledge of drug-induced behavioral teratogenesis to a new mechanism of anticonvulsant action.

Anticonvulsant drug-induced cell death in the developing white matter of the rodent brain

OBJECTIVE

During critical periods of brain development, both seizures and anticonvulsant medications can affect neurodevelopmental outcomes. In rodent models, many anticonvulsants trigger neuronal apoptosis. However, white matter apoptosis (WMA) has not been examined after anticonvulsant drug treatment. Herein, we sought to determine if anticonvulsant drugs induced apoptosis in the developing white matter (WM) in a rodent model.

METHODS

Postnatal day (P)7 rats were treated with phenobarbital (PB-75), MK-801 (dizocilpine, 0.5), lamotrigine (LTG-20), carbamazepine (CBZ-100), phenytoin (PHT-50), levetiracetam (LEV-250), or saline; all doses are mg/kg. Brain tissue collected 24 h after treatment was stained using the terminal deoxynucleotidyl transferase dUTP nick end labeling method. The number of degenerating cells within WM, that is, anterior commissure (AC), corpus callosum, cingulum, and hippocampus-associated WM tracts, was quantified.

RESULTS

Saline-treated rats showed low baseline level of apoptosis in developing WM on P8 in all the areas examined. PB, PHT, and MK-801 significantly increased apoptosis in all four brain areas examined. Exposure to CBZ, LTG, or LEV failed to increase apoptosis in all regions.

SIGNIFICANCE

Commonly used anticonvulsants (PB, PHT) cause apoptosis in the developing WM in a rat model; the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 has a similar effect. These results are consistent with reports of anesthesia-induced WMA during brain development. Consistent with the lack of neuronal apoptosis caused by LTG, LEV, and CBZ, these drugs did not cause WMA. Many infants treated with anticonvulsant drugs have underlying neurologic injury, including WM damage (e.g., following intraventricular hemorrhage [IVH] or hypoxic-ischemic encephalopathy [HIE]). The degree to which anticonvulsant drug treatment will alter outcomes in the presence of underlying injury remains to be examined, but avoiding drugs (when possible) that induce WMA may be beneficial.

Profile of retigabine-induced neuronal apoptosis in the developing rat brain

OBJECTIVE

Acute neonatal exposure to some, but not all, anticonvulsant drugs induces a profound increase in neuronal apoptosis in rats. Phenobarbital and phenytoin induce apoptosis at a therapeutically relevant dose range, lamotrigine and carbamazepine do so only at supratherapeutic doses or in polytherapy, and valproate does so even at subtherapeutic doses. Levetiracetam is devoid of pro-apoptotic effects. Retigabine, a new-generation drug, acts uniquely by enhancing the M-type potassium current. Because its safety profile in developing animals is unstudied, we sought to determine if retigabine would induce apoptosis.

METHODS

Postnatal day (P) 7 rat pups were treated with retigabine (5-30 mg/kg), vehicle (saline), or comparator drugs (phenobarbital, lamotrigine, levetiracetam, or carbamazepine). Cell death was assessed using amino-cupric-silver staining. A separate group of animals was treated repeatedly (three times over 24 h) with retigabine (15 mg/kg) or vehicle. To establish a pharmacokinetic profile for retigabine, we measured plasma and brain levels after drug treatment.

RESULTS

Consistent with prior studies from our group and others, we found phenobarbital-induced cell death throughout thalamus, nucleus accumbens, and several neocortical areas. By contrast, levetiracetam, lamotrigine, and carbamazepine were found to have no appreciable apoptotic effect on the aforementioned structures. Acute (single) exposure to retigabine, even at doses of 30 mg/kg, was also without effect on apoptosis. However, repeated (three times) exposure to retigabine triggered apoptosis in a subset of brain areas. The half-life of retigabine in plasma was 2.5 h, with appreciable concentrations reached in the brain within 1 h of administration.

SIGNIFICANCE

These data demonstrate that retigabine, like many other anticonvulsant drugs, is capable of triggering neuronal apoptosis in the developing rat brain. Unlike other drugs, repeated dosing of retigabine was necessary to induce this effect. This may be due to its shorter half-life as compared to other drugs, such as phenobarbital.

Phenobarbital use and neurological problems in FMR1 premutation carriers

Fragile X Syndrome (FXS) is a neurodevelopmental disorder caused by a CGG expansion in the FMR1 gene located at Xq27.3. Patients with the premutation in FMR1 present specific clinical problems associated with the number of CGG repeats (55-200 CGG repeats). Premutation carriers have elevated FMR1 mRNA expression levels, which have been associated with neurotoxicity potentially causing neurodevelopmental problems or neurological problems associated with aging. However, cognitive impairments or neurological problems may also be related to increased vulnerability of premutation carriers to neurotoxicants, including phenobarbital. Here we present a study of three sisters with the premutation who were exposed differentially to phenobarbital therapy throughout their lives, allowing us to compare the neurological effects of this drug in these patients.

[Protective effect of succinic acid on cerebellar Purkinje cells of neonatal rats with convulsion]

OBJECTIVE

To investigate the protective effect of succinic acid (SA) on the cerebellar Purkinje cells (PCs) of neonatal rats with convulsion.

METHODS

A total of 120 healthy neonatal Sprague-Dawley rats aged 7 days were randomly divided into a neonatal period group and a developmental period group. Each of the two groups were further divided into 6 sub-groups: normal control, convulsion model, low-dose phenobarbital (PB) (30 mg/kg), high-dose PB (120 mg/kg), low-dose SA (30 mg/kg), and high-dose SA (120 mg/kg). Intraperitoneal injection of pentylenetetrazole was performed to establish the convulsion model. The normal control group was treated with normal saline instead. The rats in the neonatal group were sacrificed at 30 minutes after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Those in the developmental group were sacrificed 30 days after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Whole cell patch clamp technique was used to record the action potential (AP) of PCs in the cerebellar slices of neonatal rats; the parallel fibers (PF) were stimulated at a low frequency to induce excitatory postsynaptic current (EPSC). The effect of SA on long-term depression (LTD) of PCs was observed.

RESULTS

Compared with the normal control groups, the neonatal and developmental rats with convulsion had a significantly higher AP frequency of PCs (P<0.05), and the developmental rats with convulsion had a significantly decreased threshold stimulus (P<0.01) and a significantly greater inhibition of the amplitude of EPSC in PCs (P<0.05). Compared with the normal control groups, the neonatal and developmental rats with convulsion in the high-dose PB groups had a significantly decreased threshold stimulus (P<0.01), a significantly higher AP frequency of PCs (P<0.05), and a significantly greater inhibition of EPSC in PCs (P<0.05). Compared with the neonatal and developmental rats in the convulsion model groups, those in the high-dose SA groups had a significantly decreased AP frequency of PCs (P<0.05). The developmental rats in the low- and high-dose SA groups had a significantly higher AP threshold than those in the convulsion model group (P<0.05).

CONCLUSIONS

The high excitability of PCs and the abnormal PF-PC synaptic plasticity caused by convulsion in neonatal rats may last to the developmental period, which can be aggravated by PB, while SA can reduce the excitability of PCs in neonatal rats with convulsion and repair the short- and long-term abnormalities of LTD of PCs caused by convulsion.

[Protective effect of succinic acid on cerebellar Purkinje cells of neonatal rats with convulsion]

OBJECTIVE

To investigate the protective effect of succinic acid (SA) on the cerebellar Purkinje cells (PCs) of neonatal rats with convulsion.

METHODS

A total of 120 healthy neonatal Sprague-Dawley rats aged 7 days were randomly divided into a neonatal period group and a developmental period group. Each of the two groups were further divided into 6 sub-groups: normal control, convulsion model, low-dose phenobarbital (PB) (30 mg/kg), high-dose PB (120 mg/kg), low-dose SA (30 mg/kg), and high-dose SA (120 mg/kg). Intraperitoneal injection of pentylenetetrazole was performed to establish the convulsion model. The normal control group was treated with normal saline instead. The rats in the neonatal group were sacrificed at 30 minutes after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Those in the developmental group were sacrificed 30 days after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Whole cell patch clamp technique was used to record the action potential (AP) of PCs in the cerebellar slices of neonatal rats; the parallel fibers (PF) were stimulated at a low frequency to induce excitatory postsynaptic current (EPSC). The effect of SA on long-term depression (LTD) of PCs was observed.

RESULTS

Compared with the normal control groups, the neonatal and developmental rats with convulsion had a significantly higher AP frequency of PCs (P<0.05), and the developmental rats with convulsion had a significantly decreased threshold stimulus (P<0.01) and a significantly greater inhibition of the amplitude of EPSC in PCs (P<0.05). Compared with the normal control groups, the neonatal and developmental rats with convulsion in the high-dose PB groups had a significantly decreased threshold stimulus (P<0.01), a significantly higher AP frequency of PCs (P<0.05), and a significantly greater inhibition of EPSC in PCs (P<0.05). Compared with the neonatal and developmental rats in the convulsion model groups, those in the high-dose SA groups had a significantly decreased AP frequency of PCs (P<0.05). The developmental rats in the low- and high-dose SA groups had a significantly higher AP threshold than those in the convulsion model group (P<0.05).

CONCLUSIONS

The high excitability of PCs and the abnormal PF-PC synaptic plasticity caused by convulsion in neonatal rats may last to the developmental period, which can be aggravated by PB, while SA can reduce the excitability of PCs in neonatal rats with convulsion and repair the short- and long-term abnormalities of LTD of PCs caused by convulsion.

Hippocampal granule cell pathology in epilepsy - a possible structural basis for comorbidities of epilepsy?

Temporal lobe epilepsy in both animals and humans is characterized by abnormally integrated hippocampal dentate granule cells. Among other abnormalities, these cells make axonal connections with inappropriate targets, grow dendrites in the wrong direction, and migrate to ectopic locations. These changes promote the formation of recurrent excitatory circuits, leading to the appealing hypothesis that these abnormal cells may by epileptogenic. While this hypothesis has been the subject of intense study, less attention has been paid to the possibility that abnormal granule cells in the epileptic brain may also contribute to comorbidities associated with the disease. Epilepsy is associated with a variety of general findings, such as memory disturbances and cognitive dysfunction, and is often comorbid with a number of other conditions, including schizophrenia and autism. Interestingly, recent studies implicate disruption of common genes and gene pathways in all three diseases. Moreover, while neuropsychiatric conditions are associated with changes in a variety of brain regions, granule cell abnormalities in temporal lobe epilepsy appear to be phenocopies of granule cell deficits produced by genetic mouse models of autism and schizophrenia, suggesting that granule cell dysmorphogenesis may be a common factor uniting these seemingly diverse diseases. Disruption of common signaling pathways regulating granule cell neurogenesis may begin to provide mechanistic insight into the cooccurrence of temporal lobe epilepsy and cognitive and behavioral disorders.

Brief postnatal exposure to phenobarbital impairs passive avoidance learning and sensorimotor gating in rats

Phenobarbital is the most commonly utilized drug for the treatment of neonatal seizures. However, mounting preclinical evidence suggests that even brief exposure to phenobarbital in the neonatal period can induce neuronal apoptosis, alterations in synaptic development, and long-lasting changes in behavioral functions. In the present report, we treated neonatal rat pups with phenobarbital and evaluated behavior in adulthood. Pups were treated initially with a loading dose (80 mg/kg) on postnatal day (P)7 and with a lower dose (40 mg/kg) on P8 and P9. We examined sensorimotor gating (prepulse inhibition), passive avoidance, and conditioned place preference for cocaine when the animals reached adulthood. Consistent with our previous reports, we found that three days of neonatal exposure to phenobarbital significantly impaired prepulse inhibition compared with vehicle-exposed control animals. Using a step-though passive avoidance paradigm, we found that animals exposed to phenobarbital as neonates and tested as adults showed significant deficits in passive avoidance retention compared with matched controls, indicating impairment in associative memory and/or recall. Finally, we examined place preference conditioning in response to cocaine. Phenobarbital exposure did not alter the normal conditioned place preference associated with cocaine exposure. Our findings expand the profile of behavioral toxicity induced by phenobarbital.

Anesthesia and the developing brain: relevance to the pediatric cardiac surgery

Anesthetic neurotoxicity has been a hot topic in anesthesia for the past decade. It is of special interest to pediatric anesthesiologists. A subgroup of children potentially at greater risk for anesthetic neurotoxicity, based on a prolonged anesthetic exposure early in development, are those children receiving anesthesia for surgical repair of congenital heart disease. These children have a known risk of neurologic deficit after cardiopulmonary bypass for surgical repair of congenital heart disease. Yet, the type of anesthesia used has not been considered as a potential etiology for their neurologic deficits. These children not only receive prolonged anesthetic exposure during surgical repair, but also receive repeated anesthetic exposures during a critical period of brain development. Their propensity to abnormal brain development, as a result of congenital heart disease, may modify their risk of anesthetic neurotoxicity. This review article provides an overview of anesthetic neurotoxicity from the perspective of a pediatric cardiac anesthesiologist and provides insight into basic science and clinical investigations as it relates to this unique group of children who have been studied over several decades for their risk of neurologic injury.

Protracted maturation of forebrain afferent connections of the ventral tegmental area in the rat

The mesocorticolimbic dopamine system has long attracted the interest of researchers concerned with the unique gamut of behavioral and mental health vulnerabilities associated with adolescence. Accordingly, the development of the mesocorticolimbic system has been studied extensively, but almost exclusively with regard to dopaminergic output, particularly in the nucleus accumbens and medial prefrontal cortex. To the contrary, the ontogeny of inputs to the ventral tegmental area (VTA), the source of mesocorticolimbic dopamine, has been neglected. This is not a trivial oversight, as the activity of VTA neurons, which reflects their capacity to transmit information about salient events, is sensitively modulated by inputs. Here, we assessed the development of VTA afferent connections using the β subunit of cholera toxin (Ctβ) as a retrograde axonal tracer in adolescent (postnatal day 39) and early adult (8-9-week-old) rats. After intra-VTA injections of Ctβ, adolescent and early adult animals exhibited qualitatively similar distributions of retrogradely labeled neurons in the sense that VTA-projecting neurons were present at all of the same rostrocaudal levels in all of the same structures in both age groups. However, quantitation of retrogradely labeled neurons revealed that adolescent brains, compared with early adult brains, had significantly fewer VTA-projecting neurons preferentially within an interconnected network of cortical and striatopallidal forebrain structures. These findings provide a novel perspective on the development of the mesocorticolimbic dopamine system and may have important implications for age-dependent specificity in the function of this system, particularly with regard to adolescent impulsivity and mental health vulnerabilities.

Efficacy of clonidine versus phenobarbital in reducing neonatal morphine sulfate therapy days for neonatal abstinence syndrome. A prospective randomized clinical trial

OBJECTIVE

To compare the efficacy of clonidine versus phenobarbital in reducing morphine sulfate treatment days for neonatal abstinence syndrome (NAS).

STUDY DESIGN

Prospective, non-blinded, block randomized trial at a single level III NICU (Neonatal Intensive Care Unit). Eligible infants were treated with a combination of medications as per protocol. Primary outcome was treatment days with morphine sulfate. Secondary outcomes were the mean total morphine sulfate dose, outpatient phenobarbital days, adverse events and treatment failures.

RESULTS

A total of 82 infants were eligible, of which 68 were randomized with 34 infants in each study group. Adjusting for covariates phenobarbital as compared with clonidine had shorter morphine sulfate treatment days (-4.6, 95% confidence interval (CI): -0.3, -8.9; P=0.037) with no difference in average morphine sulfate total dose (1.1 mg kg(-1), 95% CI: -0.1, 2.4; P=0.069). Post-discharge phenobarbital was continued for an average of 3.8 months (range 1 to 8 months). No other significant differences were noted.

CONCLUSION

Phenobarbital as adjunct had clinically nonsignificant shorter inpatient but significant overall longer therapy time as compared with clonidine.

Developmental effects of neonatal isoflurane and sevoflurane exposure in rats

BACKGROUND

The general anesthetics, isoflurane and sevoflurane, cause developmental abnormalities in neonatal animal models via incompletely understood mechanisms. Despite many common molecular targets, isoflurane and sevoflurane exhibit substantial differences in their actions. The authors sought to determine whether these differences can also be detected at the level of neurodevelopmental effects.

METHODS

Postnatal rats, 4-6 days old, were exposed to 1.2% isoflurane or 2.1% sevoflurane for 1-6 h and studied for immediate and delayed effects.

RESULTS

Isoflurane exposure was associated with weaker seizure-like electroencephalogram patterns than sevoflurane exposure. Confronted with a new environment at a juvenile age, the sevoflurane-exposed rats spent significantly more time in an "immobile" state than unexposed rats. Electroencephalographic (mean ± SE, 55.5 ± 12.80 s vs. 14.86 ± 7.03 s; P = 0.014; n = 6-7) and spontaneous behavior (F(2,39) = 4.43; P = 0.018) effects of sevoflurane were significantly diminished by pretreatment with the Na-K-2Cl cotransporter inhibitor bumetanide, whereas those of isoflurane were not. Pretreatment with bumetanide, however, diminished isoflurane-induced activation of caspase-3 in the cerebral cortex (F(2,8) = 22.869; P = 0.002) and prevented impairment in sensorimotor gating function (F(2,36) = 5.978; P = 0.006).

CONCLUSIONS

These findings in combination with results previously reported by the authors suggest that isoflurane and sevoflurane produce developmental effects acting via similar mechanisms that involve an anesthetic-induced increase in neuronal activity. At the same time, differences in their effects suggest differences in the mediating mechanisms and in their relative safety profile for neonatal anesthesia.

Melatonin potentiates the anticonvulsant action of phenobarbital in neonatal rats

Phenobarbital is the most commonly utilized drug for neonatal seizures. However, questions regarding safety and efficacy of this drug make it particularly compelling to identify adjunct therapies that could boost therapeutic benefit. One potential adjunct therapy is melatonin. Melatonin is used clinically in neonatal and pediatric populations, and moreover, it exerts anticonvulsant actions in adult rats. However, it has not been previously evaluated for anticonvulsant effects in neonatal rats. Here, we tested the hypothesis that melatonin would exert anticonvulsant effects, either alone, or in combination with phenobarbital. Postnatal day (P)7 rats were treated with phenobarbital (0-40mg/kg) and/or melatonin (0-80mg/kg) prior to chemoconvulsant challenge with pentylenetetrazole (100mg/kg). We found that melatonin significantly potentiated the anticonvulsant efficacy of phenobarbital, but did not exert anticonvulsant effects on its own. These data provide additional evidence for the further examination of melatonin as an adjunct therapy in neonatal/pediatric epilepsy.

Neonatal seizures therapy: we are still looking for the efficacious drug

Therapeutic options currently available for neonatal seizures are still unsatisfactory both in terms of efficacy and of risk for long-term neurotoxicity, even if there is growing recognition of their potential to worsen neurodevelopmental outcome. A recent paper by Slaughter and colleagues entitled “Pharmacological treatment of neonatal seizures: a systematic review” has been published with the aim to provide a treatment algorithm, but, due to the relative paucity of clinical studies, it relies mainly on traditional antiepileptic drugs and does not distinguish between different neonatal populations, especially preterm and hypothermic neonates, who might require a dedicated approach in order to improve seizure control and reduce side effects.

Searching for new targets for treatment of pediatric epilepsy

The highest incidence of seizures in humans occurs during the first year of life. The high susceptibility to seizures in neonates and infants is paralleled by animal studies showing a high propensity to seizures during early life. The immature brain is highly susceptible to seizures because of an imbalance of excitation and inhibition. While the primary outcome determinant of early-life seizures is etiology, there is evidence that seizures which are frequent or prolonged can result in long-term adverse consequences, and there is a consensus that recurrent early-life seizures should be treated. Unfortunately, seizures in many neonates and children remain refractory to therapy. There is therefore a pressing need for new seizure drugs as well as antiepileptic targets in children. In this review, we focus on mechanisms of early-life seizures, such as hypoxia-ischemia, and novel molecular targets, including the hyperpolarization-activated cyclic nucleotide-gated channels.

Psychopathology in pediatric epilepsy: role of antiepileptic drugs

Children with epilepsy are usually treated with antiepileptic drugs (AEDS). Some AEDs adversely affect behavior in susceptible children. Since psychiatric comorbidity is prevalent in pediatric epilepsy, this paper attempts to disentangle these AED side effects from the psychopathology associated with this illness. It first outlines the clinical and methodological problems involved in determining if AEDs contribute to the behavior and emotional problems of children with epilepsy. It then presents research evidence for and against the role AEDs play in the psychopathology of children with epilepsy, and outlines how future studies might investigate this problem. A brief description of how to clinically separate out AED effects from the complex illness-related and psychosocial factors that contribute to the behavior difficulties of children with epilepsy concludes the paper.

Roles of aldosterone and oxytocin in abnormalities caused by sevoflurane anesthesia in neonatal rats

BACKGROUND

The authors sought to determine whether subjects with pathophysiological conditions that are characterized by increased concentrations of aldosterone have increased susceptibility to the side effects of neonatal anesthesia with sevoflurane.

METHODS

Postnatal day 4-20 (P4-P20) rats were exposed to sevoflurane, 6% and 2.1%, for 3 min and 60-360 min, respectively. Exogenous aldosterone was administered to imitate pathophysiological conditions with increased concentrations of aldosterone.

RESULTS

Six hours of anesthesia with sevoflurane on P4-P5 rats resulted in a more than 30-fold increase in serum concentrations of aldosterone (7.02 ± 1.61 ng/dl vs. 263.75 ± 22.31 ng/dl, mean ± SE, n = 5-6) and reduced prepulse inhibition of the acoustic startle response (F(2,37) = 5.66, P < 0.001). Administration of exogenous aldosterone during anesthesia with sevoflurane enhanced seizure-like electroencephalogram patterns in neonatal rats (48.25 ± 15.91 s vs. 222.00 ± 53.87 s, mean ± SE, n = 4) but did not affect electroencephalographic activity in older rats. Exogenous aldosterone increased activation of caspase-3 (F(3,28) = 11.02, P < 0.001) and disruption of prepulse inhibition of startle (F(3,46) = 6.36; P = 0.001) caused by sevoflurane. Intracerebral administration of oxytocin receptor agonists resulted in depressed seizure-like electroencephalogram patterns (F(2,17) = 6.37, P = 0.009), reduced activation of caspase-3 (t(11) = 2.83, P = 0.016), and disruption of prepulse inhibition of startle (t(7) = -2.9; P = 0.023) caused by sevoflurane.

CONCLUSIONS

These results suggest that adverse developmental effects of neonatal anesthesia with sevoflurane may involve both central and peripheral actions of the anesthetic. Subjects with increased concentrations of aldosterone may be more vulnerable, whereas intracerebral oxytocin receptor agonists may be neuroprotective.

The effect of injury severity on behavior: a phenotypic study of cognitive and emotional deficits after mild, moderate, and severe controlled cortical impact injury in mice

Traumatic brain injury (TBI) can cause a broad array of behavioral problems including cognitive and emotional deficits. Human studies comparing neurobehavioral outcomes after TBI suggest that cognitive impairments increase with injury severity, but emotional problems such as anxiety and depression do not. To determine whether cognitive and emotional impairments increase as a function of injury severity we exposed mice to sham, mild, moderate, or severe controlled cortical impact (CCI) and evaluated performance on a variety of neurobehavioral tests in the same animals before assessing lesion volume as a histological measure of injury severity. Increasing cortical impact depth successfully produced lesions of increasing severity in our model. We found that cognitive impairments in the Morris water maze increased with injury severity, as did the degree of contralateral torso flexion, a measure of unilateral striatal damage. TBI also caused deficits in emotional behavior as quantified in the forced swim test, elevated-plus maze, and prepulse inhibition of acoustic startle, but these deficits were not dependent on injury severity. Stepwise regression analyses revealed that Morris water maze performance and torso flexion predicted the majority of the variability in lesion volume. In summary, we find that cognitive deficits increase in relation to injury severity, but emotional deficits do not. Our data suggest that the threshold for emotional changes after experimental TBI is low, with no variation in behavioral deficits seen between mild and severe brain injury.

Neonatal exposure to antiepileptic drugs disrupts striatal synaptic development

OBJECTIVE

Drug exposure during critical periods of brain development may adversely affect nervous system function, posing a challenge for treating infants. This is of particular concern for treating neonatal seizures, as early life exposure to drugs such as phenobarbital is associated with adverse neurological outcomes in patients and induction of neuronal apoptosis in animal models. The functional significance of the preclinical neurotoxicity has been questioned due to the absence of evidence for functional impairment associated with drug-induced developmental apoptosis.

METHODS

We used patch-clamp recordings to examine functional synaptic maturation in striatal medium spiny neurons from neonatal rats exposed to antiepileptic drugs with proapoptotic action (phenobarbital, phenytoin, lamotrigine) and without proapoptotic action (levetiracetam). Phenobarbital-exposed rats were also assessed for reversal learning at weaning.

RESULTS

Recordings from control animals revealed increased inhibitory and excitatory synaptic connectivity between postnatal day (P)10 and P18. This maturation was absent in rats exposed at P7 to a single dose of phenobarbital, phenytoin, or lamotrigine. Additionally, phenobarbital exposure impaired striatal-mediated behavior on P25. Neuroprotective pretreatment with melatonin, which prevents drug-induced neurodevelopmental apoptosis, prevented the drug-induced disruption in maturation. Levetiracetam was found not to disrupt synaptic development.

INTERPRETATION

Our results provide the first evidence that exposure to antiepileptic drugs during a sensitive postnatal period impairs physiological maturation of synapses in neurons that survive the initial drug insult. These findings suggest a mechanism by which early life exposure to antiepileptic drugs can impact cognitive and behavioral outcomes, underscoring the need to identify therapies that control seizures without compromising synaptic maturation.