Adenosine inhibits human astrocyte proliferation independently of adenosine receptor activation

AbstractBrain adenosine concentrations can reach micromolar concentrations in stressful situations such as stroke, neurodegenerative diseases or hypoxic regions of brain tumours. Adenosine can act by receptor ‐independent mechanism by reversing the reaction catalysed by S‐adenosylhomocysteine (SAH) hydrolase, leading to SAH accumulation and inhibition of S‐adenosylmethionine (SAM)‐dependent methyltransferases. Astrocytes are essential in maintaining brain homeostasis but their pathological activa tion and uncontrolled proliferation plays a role in neurodegeneration and glioma. Adenosine can affect cell proliferation, but the effect of increased adenosine concentration on proliferation of astrocytes is not clarified and was addressed in present work.Human astrocytes (HA) were treated for 3  days with test drugs. Cell proliferation/viability was assessed by the MTT assay and by cell counting. Cell death was evaluated by assessing lactate dehydrogenase (LDH) release and by western blot analysis of αII‐Spectrin cleavage. 30µM‐Adenosine caused a 40%±3% (p <  .05,n = 5) reduction in cell proliferation/viability, an effect reversed by 2U/ml‐adenosine deaminase, but unchanged in the presence of antagonists of any of the adenosine receptors. Adenosine alone did not induce cell death. 100µM‐Homocysteine alone caused 16%±3% (p <  .05) decrease in HA proliferation. Combined action of adenosine and homocysteine decreased HA proliferation by 76%±4%, an ef...
Source: Journal of Neurochemistry - Category: Neuroscience Authors: Tags: ORIGINAL ARTICLE Source Type: research