A Complex Neuroprotective Effect of Alpha-2-Adrenergic Receptor Agonists in a Model of Cerebral Ischemia–Reoxygenation In Vitro

• Published in: Biochemistry (Moscow). Supplement series A, Membrane and cell biology Vol. 13; no. 4; pp. 319 - 333
• Main Authors: Gaidin, S. G., Turovskaya, M. V., Mal’tseva, V. N., Zinchenko, V. P., Blinova, E. V., Turovsky, E. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.10.2019; Springer Nature B.V
• Subjects: Adrenergic receptors; Agonists; Apoptosis; Astrocytes; Bcl-2 protein; Biomedical and Life Sciences; Biotechnology; Calcium (intracellular); Calcium ions; Calcium signalling; Caspase-3; Cell activation; Cell Biology; Cell culture; Cell death; Deprivation; Fluorescence; Gene expression; Genes; Glucose; Inflammation; Interleukin 1; Ischemia; Life Sciences; Neurons; Neuroprotection; Oscillations; Oxygen; p53 Protein; Pretreatment; Stat3 protein; Tumor necrosis factor-α; hyperexcitation; adrenergic receptors; calcium ions; apoptosis; astrocytes; neurons; neuroprotectors; ischemia
• ISSN: 1990-7478; 1990-7494
• DOI: 10.1134/S1990747819040068

— The mechanism of the neuroprotective action of α 2 -adrenergic receptor agonists in a model of oxygen-glucose deprivation (OGD) in vitro was investigated. Using fluorescent microscopy, immunostaining, inhibitor analysis, and real-time PCR analysis, we demonstrated that OGD evokes a biphasic [Ca 2+ ] i increase in all cells. Initial Ca 2+ impulse in astrocytes and Ca 2+ oscillations in neurons were followed by a slower global increase of [Ca 2+ ] i in both cell populations. Accumulation of pro-inflammatory factors, such as IL1b and TNFα, was observed during 40-min OGD. It was established that reoxygenation is followed by hyperexcitation of neurons, caspase-3 activation, and subsequent cell death. We showed that a 24-h pretreatment of cell cultures with selective α 2 -adrenergic receptor agonists guanfacine and UK-14,304 abolished the global [Ca 2+ ] i increase in astrocytes and neurons but did not suppress the first phase of the OGD-induced Ca 2+ impulse in astrocytes. In addition, the number of dead cells after OGD was decreased in cell cultures pretreated with the α 2 -agonists. Guanfacine inhibited caspase-3 activation and suppressed apoptosis in our experiments. In particular, the expression of antiapoptotic genes Stat3 and Bcl-2 was enhanced after the pretreatment with guanfacine. On the contrary, the expression of proapoptotic genes ( Socs-3 , p53 , fas, and Ikk ) was decreased. Moreover, application of guanfacine evoked Ca 2+ response in astrocytes and led to Ca 2+ -mediated ATP release and this way suppressed hyperexcitation of the neurons. Thus, activation of astrocytes and Ca 2+ -mediated ATP release possibly contribute to the complex neuroprotective effects of the α 2 -adrenergic receptor agonists.