engleski

Therapeutic opportunities of neurosteroids in Ischemic Brain Injury

Introduction: Ischemic brain injury is a complex syndrome of various pathophysiological changes caused by reduction of blood supply to the brain tissue and represents one of the major causes of death and disability today. Deprivation of oxygen, glucose and other nutrients in the brain, as well as lack of elimination of metabolic toxic products, induce complex cascade of biochemical and molecular events that lead to neuronal damage and death. It has been shown that neurosteroids dehydroepiandrosterone (DHEA) and its sulfate (DHEAS), together referred as DHEA(S), have a wide range of beneficial and protective effects in the brain. These neurosteroids act as negative allosteric modulators of GABAA receptors and as positive allosteric modulators of NMDA and sigma receptors and therefore might exert potential antidepressant, anxiogenic, cognitive- and memory-enhancing as well as neuroprotective properties. The aim of our study was to investigate therapeutic potential of DHEA(S) in the ischemic brain injury using in vitro and in vivo models of oxygen and glucose deprivation. Methods: As an in vivo model of ischemic brain injury, adult Wistar male rats were subjected to bilateral occlusion of common carotid arteries (BCAO) for 5 minutes, and after 24 h, rats were treated with DHEA(S). Cognitive behavioral functioning was examined 7 days after BCAO using object recognition and object location tests. The effect of DHEA(S) on ischemia-induced pathohistological brain changes was investigated ex vivo by analyzing Bcl-2 and Bax protein levels in cytosolic and mitochondrial fractions of hippocampus and prefrontal cortex, using Western blot. As an in vitro model of ischemic brain injury, HEK 293 cells, non-transfected and stably transfected with 122S GABAA receptors, were exposed to oxygen and glucose deprivation/reperfusion (OGDR) using gas-tight modular incubator chamber, before and after DHEA(S) treatment. Results: The preliminary results obtained on HEK 293 cells, non-transfected and stably transfected with 122S GABAA receptor demonstrated protective effects of DHEA(S), administered both before and after OGDR, which seem partially mediated via GABAA receptors. Object recognition and object location tests, performed on rats 7 days after BCAO, showed protective effect of DHEA(S) on cognitive behavioral functioning. Preliminary results of Bcl-2/Bax protein expression analysis obtained on cytosolic and mitochondrial fractions of hippocampus and prefrontal cortex suggested anti-apoptotic effects of DHEA(S). Conclusion: Our preliminary findings, obtained using both in vitro and in vivo models of ischemic brain injury, demonstrated protective effects of DHEA(S) against ischemia-induced neuronal damage and death, which probably at least partially involve anti-apoptotic mechanisms and GABAA receptors. However, further experiments investigating various pathways of neuronal cell death and survival are needed in order to elucidate complex molecular mechanisms of potential therapeutic effects of DHEA(S) in ischemic brain injury.

Ischemic brain injury ; Neurosteroids DHEA(S) ; Wistar rats ; HEK 293 cells ; Protective effects

nije evidentirano