Hypoxia/Reoxygenation Impairs Memory Formation via Adenosine-Dependent Activation of Caspase 1

Abstract

After hypoxia, a critical adverse outcome is the inability to create new memories. How anterograde amnesia develops or resolves remains elusive, but a link to brain-based IL-1 is suggested due to the vital role of IL-1 in both learning and brain injury. We examined memory formation in mice exposed to acute hypoxia. After reoxygenation, memory recall recovered faster than memory formationimpacting novel object recognition and cued fear conditioning but not spatially cued Y-maze performance. The ability of mice to form new memories after hypoxia/reoxygenation was accelerated in IL-1 receptor 1 knockout (IL-1R1 KO) mice, in mice receiving IL-1 receptor antagonist (IL-1RA) and in mice given the caspase 1 inhibitor, Ac-YVAD-CMK. Mechanistically, hypoxia/reoxygenation more than doubled caspase 1 activity in the brain which was localized to the amygdala compared to the hippocampus. This reoxygenation-dependent activation of caspase 1 was prevented by broad-spectrum adenosine receptor (AR) antagonism with caffeine and by targeted A1/A2A AR antagonism with 8-cyclopentyl-1, 3-dipropylxanthine + 3, 7-dimethyl-1-propargylxanthine. Additionally, perfusion of adenosine activated caspase 1 in the brain while caffeine blocked this action by adenosine. Finally, resolution of anterograde amnesia was improved by both caffeine and by targeted A1/A2A AR antagonism. These findings indicate that amygdala-based anterograde amnesia after hypoxia/reoxygenation is sustained by IL-1β generated through adenosine-dependent activation of caspase 1 after reoxygenation.

Early single Aspirin-triggered Lipoxin blocked morphine anti-nociception tolerance through inhibiting NALP1 inflammasome: Involvement of PI3k/Akt signaling pathway

“…The neuron-localized expression pattern of Caspase-1 was reported to be associated with NALP1 inflammasome activation in mediating the inflammatory cascade in central nervous system after early onset (Chiu et al, 2012;de Rivero Vaccari et al, 2008;Karatas et al, 2013;Silverman et al, 2009;Tomura et al, 2012). Tissues were harvested 2 h after the 4th subcutaneous injection and double immunofluorescence was carried out to determine the cellular type of NALP1 expression.…”

Adenosine through the A2A adenosine receptor increases IL-1β in the brain contributing to anxiety

“…As we have described (Chiu et al, 2012), perfused whole brains were frozen in liquid nitrogen then freeze fractured in a reaction buffer containing 50 mM NaCl (Fisher Scientific, Fair Lawn, NJ), 10% glycerol, 1 mM DTT, 1 mM EDTA, 1 mM bestatin, 1 mM pepstatin (EMD4Bioscience, Darmstadt, Germany), 1 mM 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride and 50 mM HEPES, pH 7.4 (USB Corporation, Cleveland, OH) using a Qiagen TissueLyser II (Valencia, CA). Lysates were clarified at 16,000 × g for 15 min at 4° C and the supernatant protein concentrations determined using the Bio-Rad DC Protein Assay (Hercules, CA) and a BioTek ELx800 Absorbance Microplate Reader (Winooski, VT).…”

“…As we have described (Chiu et al, 2012), mice were euthanized via CO 2 asphyxiation and the left ventricle immediately was pieced with a BD 23 gage 1.25 inch needle (Franklin Lakes, NJ) attached to a BD 30 mL syringe. Mice, as indicated, were perfused with 30 mL of PBS (3 mM KCl, 138 mM NaCl, 8 mM dibasic sodium phosphate, 2 mM monobasic potassium phosphate, pH of 7.4) with or without 50 μM adenosine, 1 μM 8-(3-chlorostyryl)caffeine (CSC), 100 nM KT5720 or 200 μM glyburide.…”

“…Lysates were clarified and supernatant protein concentrations measured as above. IL-1β was measured in 50 μL of lysate using the Bio-Rad Bio-Plex Promouse Cytokine Group I Cytokine Assay and the Milliplex Mouse Cytokine/Chemokine Magnetic Bead Panel on a Luminex 100 System (Austin, TX) by methods similar to those we have described (Chiu et al, 2012). The Luminex 100 System was validated and calibrated using the Bio-Plex validation Kit 4.0 on the day of assay.…”

“…Recently, we demonstrated that the purine nucleoside, adenosine, released from cells during oxidative stress activates caspase-1 in the amygdala (Chiu et al, 2012). There are four described ARs that respond to extracellular adenosine (Fredholm et al, 2001) with the A2A AR being preferentially expressed in the amygdala when compared to the hippocampus (Rosin et al, 1998).…”