Brain injury is among the most prominent effects of prolonged alcohol use or abuse and evidence suggests that females may be more sensitive than males to the neurotoxic effect of prolonged alcohol intake. Thus, examination of biochemical pathways involved in this form of brain injury may be of value in identifying therapeutic targets to be exploited in treating alcohol-related brain injury. Excess activity of N-methyl-D-asparate (NMDA)- type glutamate receptors has been implicated in both the behavioral and neurotoxic effects of alcoholism, particularly during alcohol withdrawal, when excess release of glutamate and polyamines occurs. Preliminary findings suggest that the rat female brain may be more sensitive to the toxic effects of polyamine exposure during ethanol withdrawal. Polyamines are endogenous substances that act as allosteric activators of NMDA receptors at NR2 subunits. Substances that further promote activity of NMDA receptor systems, such as glucocorticoids, are hypothesized to exacerbate alcohol withdrawal effects. Indeed, prolonged alcohol intake is associated with hypercortisolemia resulting from alcohol effects the hypothalamic pituitary adrenal (HPA) axis. However, the consequences of elevated stress hormone release with regard to alcohol-related neuronal injury have been little studied, particularly with regard to potential sex differences that may exist. The proposed in vitro and in vivo rodent studies will test the hypothesis that alcohol-induced activation of the HPA axis promotes NMDA receptor- mediated seizure and/or neurotoxicity during alcohol withdrawal in a sex-dependent manner by: (1) stimulating the synthesis of polyamines via upregulation of the synthetic enzyme ornithine decarboxylase, an effect dependent upon glucocorticoid receptor (GR) activation;and (2) upregulating the expression of polyamine-sensitive NR2B subunits, thus, promoting NMDA channel opening and neuronal excitation and/or neurotoxicity in a GR-dependent manner. These studies will employ biochemical, immunohistochemical, confocal imaging, and behavioral studies using an in vivo "moderate" binge-alcohol exposure paradigm that produces peak BALs of ~160 mg/dl and organotypic hippocampal slice cultures, in parallel studies.
The aim of these studies is to elucidate the means by which glucocorticoids may exacerbate alcohol withdrawal effects in males and females, as these relevant biochemical pathways may represent therapeutic targets to be exploited in the treatment of alcohol withdrawal effects.
Brain injury is among the most common consequences of alcohol abuse or dependence and limited evidence suggests that the female brain may be more sensitive than the male brain to injurious effects of alcohol use. These studies will examine effects of alcohol on the stress hormone response and will test the hypothesis that stress hormones stimulate biochemical cascades that produce alcohol withdrawal excitability and brain injury, particularly in the female brain. It is the goal of these studies to identify a potential novel therapeutic target for the treatment of alcohol-related brain injury.
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