Striatal GABA Receptor Alterations in Hypoxic Neonatal Rats: Role of Glucose, Oxygen and Epinephrine Treatment

GABAergic system's Injuries Induced by Sodium Sulfite in Caenorhabditis elegans Were Prevented by the Anti-Oxidative Properties of Dehydroepiandrosterone Sulfate

Several pathophysiological processes involve Hypoxia conditions, where the nervous system is affected as well. We postulate that the GABAergic system is especially sensitive. Furthermore, drugs improving the resistance to hypoxia have been investigated, such as the neurosteroid dehydroepiandrosterone sulfate (DHEAS) which has shown beneficial effects in hypoxic processes in mammals; however, at the cellular level, its exact mechanism of action has yet to be fully elucidated. Here, we used a chemical hypoxia model through sodium sulfite (SS) exposure in Caenorhabditis elegans (C. elegans), a nematode whose response to hypoxia involves pathways and cellular processes conserved in mammals, and that allows study the direct effect of DHEAS without its conversion to sex hormones. This work aimed to determine the effect of DHEAS on damage to the GABAergic system associated with SS exposure in C. elegans. Worms were subjected to nose touch response (Not Assay) and observed in epifluorescence microscopy. DHEAS decreased the shrinkage response of Not Assay and the level of damage in GABAergic neurons on SS-exposed worms. Also, the enhanced nuclear localization of DAF-16 and consequently the overexpression of chaperone HSP-16.2 by hypoxia were significantly reduced in SS + DHEAS exposed worms. As well, DHEAS increased the survival rate of worms exposed to hydrogen peroxide. These results suggest that hypoxia-caused damage over the GABAergic system was prevented at least partially by DHEAS, probably through non-genomic mechanisms that involve its antioxidant properties related to its chemical structure.

Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges

Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.

Striatal cholinergic functional alterations in hypoxic neonatal rats: Role of glucose, oxygen, and epinephrine resuscitation

Molecular processes regulating cholinergic functions play an important role in the control of respiration under hypoxia. Cholinergic alterations and its further complications in respiration due to hypoxic insult in neonatal rats and the effect of glucose, oxygen, and epinephrine resuscitation was evaluated in the present study. Receptor binding and gene expression studies were done in the corpus striatum to analyse the changes in total muscarinic receptors, muscarinic M1, M2, M3 receptors, and the enzymes involved in acetylcholine metabolism, choline acetyltransferase and acetylcholinesterase. Neonatal hypoxia decreased total muscarinic receptors with reduced expression of muscarinic M1, M2, and M3 receptor genes. The reduction in acetylcholine metabolism is indicated by the downregulated choline acetyltransferase and upregulated acetyl cholinesterase expression. These cholinergic disturbances were reversed to near control in glucose-resuscitated hypoxic neonates. The adverse effects of immediate oxygenation and epinephrine administration are also reported. The present findings points to the cholinergic alterations due to neonatal hypoxic shock and suggests a proper resuscitation method to ameliorate these striatal changes.