Hypoxia Depresses Synaptic Transmission in the Primary Motor Cortex of the Infant Rat-Role of Adenosine A1 Receptors and Nitric Oxide

The emerging role of nitric oxide in the synaptic dysfunction of vascular dementia

With an increase in global aging, the number of people affected by cerebrovascular diseases is also increasing, and the incidence of vascular dementia-closely related to cerebrovascular risk-is increasing at an epidemic rate. However, few therapeutic options exist that can markedly improve the cognitive impairment and prognosis of vascular dementia patients. Similarly in Alzheimer's disease and other neurological disorders, synaptic dysfunction is recognized as the main reason for cognitive decline. Nitric oxide is one of the ubiquitous gaseous cellular messengers involved in multiple physiological and pathological processes of the central nervous system. Recently, nitric oxide has been implicated in regulating synaptic plasticity and plays an important role in the pathogenesis of vascular dementia. This review introduces in detail the emerging role of nitric oxide in physiological and pathological states of vascular dementia and summarizes the diverse effects of nitric oxide on different aspects of synaptic dysfunction, neuroinflammation, oxidative stress, and blood-brain barrier dysfunction that underlie the progress of vascular dementia. Additionally, we propose that targeting the nitric oxide-sGC-cGMP pathway using certain specific approaches may provide a novel therapeutic strategy for vascular dementia.

Hypothermia improves neuronal network recovery in a human-derived in vitro model of oxygen-deprivation

Mild therapeutic hypothermia showed potential neuroprotective properties during and after cerebral hypoxia or ischemia in experimental animal studies. However, in clinical trials, where hypothermia is mainly applied after reperfusion, results were divergent and neurophysiological effects unclear. In our current study, we employed human-derived neuronal networks to investigate how treatment with hypothermia during hypoxia influences neuronal functionality and whether it improves post-hypoxic recovery. We differentiated neuronal networks from human induced pluripotent stem cells on micro-electrode arrays (MEAs). We studied the effect of hypothermia (34°C)-as well hyperthermia (39°C) - on neuronal functionality during and after hypoxia using MEAs. We also studied the effects on the number of synaptic puncta and cell viability by immunocytochemistry. In comparison to neuronal networks under normothermia, we found that hypothermia during hypoxia improved functional neuronal network recovery, expressed as enhanced neuronal network activity. This was associated with prevention of synaptic loss during and after the hypoxic phase. Furthermore, hypothermia improved cell viability after the hypoxic phase. Instead, hyperthermia during hypoxia had detrimental effects, with an irreversible loss of neuronal network function, loss of synaptic puncta and decreased cell viability. Our results show potential neuroprotective properties of hypothermia occurring during hypoxia, indicating that administering hypothermia to bridge the time to reperfusion may be beneficial in clinical settings.

Low-frequency stimulation of corpus callosum suppresses epileptiform activity in the cortex through γ-aminobutyric acid type B receptor and slow afterhyperpolarization-mediated reduction in tissue excitability

OBJECTIVE

Deep brain stimulation, particularly low-frequency stimulation (LFS) targeting fiber tracts, has emerged as a potential therapy for drug-resistant epilepsy (DRE) and for generalized epilepsy, both of which pose significant treatment challenges. LFS diffusely suppresses seizures in the cortex when applied to fiber tracts like the corpus callosum (CC). Nevertheless, the specific processes responsible for suppressing epileptic activity in the cortex induced by LFS remain unclear. This study investigates the mechanisms underlying the antiepileptic effect in the cortex of LFS of the CC in coronal rodent brain slices.

METHODS

An in vitro 4-aminopyridine (4-AP) seizure model of cortical seizures was generated. LFS stimulation parameters were optimized to provide the largest antiepileptic effect in the cortex when applied to the CC. Changes to tissue excitability and percent time spent seizing were measured due to LFS in artificial cerebrospinal fluid, 4-AP, and in the presence of various specific and nonspecific γ-aminobutyric acid type B (GABAB) and slow afterhyperpolarization (sAHP) antagonists.

RESULTS

LFS significantly suppressed seizure activity in the cortex, with an optimal frequency of 5 Hz (76.5%). Tissue excitability during LFS reduces across a wide range of interstimulus intervals, with a maximum reduction at 200 ms. Notably, the tissue excitability remains depressed at 1000 ms. LFS, in the presence of GABAB antagonists, had diminished seizure reduction (<15%) and failed to reduce tissue excitability in the 50-400-ms range. Tissue excitability measured with paired pulses in the 600-1000-ms range was depressed in the presence of GABAB antagonists, suggesting a different antiepileptic mechanism was active. Upon administering sAHP antagonists, seizure reduction was once again diminished (<15%). Upon administration of both sAHP and GABAB antagonists, LFS failed to provide any meaningful seizure reduction (<5%).

SIGNIFICANCE

LFS of the CC provides an antiepileptic effect in the cortex with well-understood mechanisms and could be an alternative to surgical intervention for patients suffering from DRE.

Brain Injury and Neurodegeneration: Molecular, Functional, and Translational Approach 2.0

The brain is composed of different cells, such as neurons, glia, endothelial cells, etc [...].

Neonatal Resuscitation Online Registry in Shenzhen: protocol for a prospective, multicentre, open, observational cohort study

INTRODUCTION

Preterm birth complications and neonatal asphyxia are the leading causes of neonatal mortality worldwide. Surviving preterm and asphyxiated newborns can develop neurological sequelae; therefore, timely and appropriate neonatal resuscitation is important to decrease neonatal mortality and disability rates. There are very few systematic studies on neonatal resuscitation in China, and its prognosis remains unclear. We established an online registry for neonatal resuscitation in Shenzhen based on Utstein's model and designed a prospective, multicentre, open, observational cohort study to address many of the limitations of existing studies. The aim of this study is to explore the implementation and management, risk factors and outcomes of neonatal resuscitation in Shenzhen.

METHODS AND ANALYSIS

This prospective, multicentre, open, observational cohort study will be conducted between January 2024 and December 2026 and will include >1500 newborns resuscitated at birth by positive pressure ventilation at five hospitals in Shenzhen, located in the south-central coastal area of Guangdong province, China. Maternal and infant information, resuscitation information, hospitalisation information and follow-up information will be collected. Maternal and infant information, resuscitation information and hospitalisation information will be collected from the clinical records of the patients. Follow-up information will include the results of follow-up examinations and outcomes, which will be recorded using the WeChat applet 'Resuscitation Follow-up'. These data will be provided by the neonatal guardians through the applet on their mobile phones. This study will provide a more comprehensive understanding of the implementation and management, risk factors and outcomes of neonatal resuscitation in Shenzhen; the findings will ultimately contribute to the reduction of neonatal mortality and disability rates in Shenzhen.

ETHICS AND DISSEMINATION

Our protocol has been approved by the Medical Ethics Committee of Shenzhen Luohu People's Hospital (2023-LHQRMYY-KYLL-048). We will present the study results at academic conferences and peer-reviewed paediatrics journals.

TRIAL REGISTRATION NUMBER

ChiCTR2300077368.