2-(4-(2-carboxyethyl)phenethylamino)-5--n-ethylcarboxamidoadenosine and Cerebral-Hemorrhage

The ubiquitous neuromodulator adenosine inhibits the production of several proinflammatory cytokines through activation of specific cell-surface adenosine receptors. We demonstrated recently that antisense oligonucleotides to tumor necrosis factor-alpha (TNF-alpha) are neuroprotective in a rat model of intracerebral hemorrhage. Therefore, we hypothesized that activation of adenosine receptors would provide protection against intracerebral hemorrhage-induced TNF-alpha production and inflammatory events. In vitro experiments showed that adenosine A1, A2A, and A3 receptor subtypes were present on U937 cells, and activation of these subtypes inhibited TNF-alpha production with a rank order of A2A > > A1 > A3. Prolonged treatment of U937 cells with the A2A receptor agonist 2-p-(carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS 21680) desensitized adenosine A2A, A1, and A3 receptors. CGS 21680 administration directly into the striatum immediately prior to the induction of intracerebral hemorrhage inhibited TNF-alpha mRNA and, 24 hours following induction, reduced parenchymal neutrophil infiltration (p < 0.001) and TUNEL-positive cells (p < 0.002) within and bordering the hematoma. These results suggest that pharmacological strategies targeting A2A receptors may provide effective inhibition of acute neurotoxic proinflammatory events that occur following intracerebral hemorrhage.

Topics: Adenosine; Adenylyl Cyclases; Animals; Apoptosis; Cerebral Hemorrhage; Chemotaxis, Leukocyte; Humans; In Situ Nick-End Labeling; Inflammation; Injections, Intraventricular; Male; Neutrophils; Phenethylamines; Phytohemagglutinins; Purinergic P1 Receptor Agonists; Rats; Rats, Sprague-Dawley; Receptor, Adenosine A2A; Receptor, Adenosine A3; Receptors, Purinergic P1; RNA, Messenger; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha; U937 Cells