digoxin and Brain-Ischemia

The glymphatic system plays a pivotal role in maintaining cerebral homeostasis. Chronic cerebral hypoperfusion, arising from small vessel disease or carotid stenosis, results in cerebrometabolic disturbances ultimately manifesting in white matter injury and cognitive dysfunction. However, whether the glymphatic system serves as a potential therapeutic target for white matter injury and cognitive decline during hypoperfusion remains unknown. Here, we established a mouse model of chronic cerebral hypoperfusion via bilateral common carotid artery stenosis. We found that the hypoperfusion model was associated with significant white matter injury and initial cognitive impairment in conjunction with impaired glymphatic system function. The glymphatic dysfunction was associated with altered cerebral perfusion and loss of aquaporin 4 polarization. Treatment of digoxin rescued changes in glymphatic transport, white matter structure, and cognitive function. Suppression of glymphatic functions by treatment with the AQP4 inhibitor TGN-020 abolished this protective effect of digoxin from hypoperfusion injury. Our research yields new insight into the relationship between hemodynamics, glymphatic transport, white matter injury, and cognitive changes after chronic cerebral hypoperfusion.

Topics: Animals; Brain Ischemia; Carotid Stenosis; Cognitive Dysfunction; Digoxin; Disease Models, Animal; Mice; Mice, Inbred C57BL; White Matter

Recently, cardiotonic steroids (CTS) have been shown to lead to the activation of Na,K-ATPase at low concentrations in brain, promoting neuroprotection against ischemia. We report here the results of the use of digoxin and its semisynthetic derivatives BD-14, BD-15, and BD-16 against partial chemical ischemic induction followed by reperfusion in murine neuroblastoma cells neuro-2a (N2a). For chemical ischemic induction, sodium azide (5 mM) was used for 5 hours, and then reperfusion was induced for 24 hours. Na,K-ATPase activity and protein levels were analyzed in membrane preparation of N2a cells pretreated with the compounds (150 nM), in the controls and in induced chemical ischemia. In the Na,K-ATPase activity and protein levels assays, the steroids digoxin and BD-15 demonstrated a capacity to modulate the activity of the enzyme directly, increasing its levels of expression and activity. Oxidative parameters, such as superoxide dismutase (SOD) activity, lipid peroxidation (thiobarbituric acid reactive substance), glutathione peroxidase (GPx), glutathione (GSH) levels, hydrogen peroxide content, and the amount of free radicals (reactive oxygen species) during induced chemical ischemia were also evaluated. Regarding the redox state, lipid peroxidation, hydrogen peroxide content, and GPx activity, we have observed an increase in the chemical ischemic group, and a reduction in the groups treated with CTS. SOD activity increased in all treated groups when compared to control and GSH levels decreased when treated with sodium azide and did not change with CTS treatments. Regarding the lipid profile, we saw a decrease in the content of phospholipids and cholesterol in the chemical ischemic group, and an increase in the groups treated with CTS. In conclusion, the compounds used in this study demonstrate promising results, since they appear to promote neuroprotection in cells exposed to chemical ischemia.

Topics: Animals; Brain Ischemia; Caco-2 Cells; Cell Hypoxia; Cell Line, Tumor; Cell Survival; Cholesterol; Digoxin; Gene Expression; Glutathione; Glutathione Peroxidase; Humans; Lipid Peroxidation; Mice; Models, Biological; Neurons; Neuroprotective Agents; Oxidative Stress; Phospholipids; Reactive Oxygen Species; Sodium Azide; Sodium-Potassium-Exchanging ATPase; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances

Topics: Anti-Arrhythmia Agents; Atrial Fibrillation; Brain Ischemia; Digoxin; Humans; Stroke

Digoxin and related cardiac glycosides have been used for almost 100 years in atrial fibrillation (AF). However, 2 recent analyses of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial showed inconsistent results regarding the risk of mortality associated with digoxin use. The goal of the present study was to investigate the relationship between digoxin and the risk of ischemic stroke and mortality in Asians.. This study used the National Health Insurance Research Database (NHIRD) in Taiwan. A total of 4781 patients with AF who did not receive any antithrombotic therapy were selected as the study population. Among the study population, 829 participants (17.3%) received the digoxin treatment. The risk of ischemic stroke and mortality in patients who received digoxin and those who did not was compared.. The use of digoxin was associated with an increased risk of clinical events, with an adjusted hazard ratio of 1.41 (95% confidence interval [CI], 1.17-1.70) for ischemic stroke and 1.21 (95% CI, 1.01-1.44) for all-cause mortality. In the subgroup analysis based on coexistence with heart failure or not, digoxin was a risk factor for adverse events in patients without heart failure but not in those with heart failure (interaction P < 0.001 for either end point). Among patients with AF without heart failure, the use of β-blockers was associated with better survival, with an adjusted hazard ratio of 0.48 (95% CI, 0.34-0.68).. Digoxin should be avoided for patients with AF without heart failure because it was associated with an increased risk of clinical events. β-Blockers may be a better choice for controlling ventricular rate in these patients.

Topics: Anti-Arrhythmia Agents; Atrial Fibrillation; Brain Ischemia; Cohort Studies; Digoxin; Humans; Risk Factors; Stroke

The sodium-potassium ATPase (Na/K ATPase) is a major ionic transporter in the brain and is responsible for the maintenance of the Na(+) and K(+) gradients across the cell membrane. Cardiotonic steroids such as ouabain, digoxin and marinobufagenin are well-characterized inhibitors of the Na/K ATPase. Recently, cardiotonic steroids have been shown to have additional effects at concentrations below their IC(50) for pumping. The cardiotonic steroids ouabain, digoxin, and marinobufagenin all show an inverted U-shaped dose-response curve with inhibition of pumping at concentrations near their IC(50), while increasing Na/K ATPase activity at doses below their IC(50). This stimulatory effect of cardiotonic steroids was observed in vitro in hippocampal slice cultures as well as in the hippocampus in vivo. Increased Na/K ATPase activity has been shown to protect slice culture neurons from hypoxia-hypoglycemia. Ouabain protected slice culture neurons from experimental ischemia at concentrations that increased Na/K ATPase. This protective effect was observed when ouabain was dosed 30min before, or 2h following experimental ischemia. Ouabain no longer protected against experimental ischemia if the increase of Na/K ATPase was blocked. These data suggest that the protective effect of ouabain was due to increased Na/K ATPase activity. The demonstration of a neuroprotective effect of cardiotonic steroids could potentially assist in the treatment of stroke since digoxin, one of the cardiotonic steroids examined in this study, has approval by the Food and Drug Administration and can be safely administered at the concentrations that increase Na/K ATPase activity.

Topics: Animals; Brain Ischemia; Bufanolides; Cardiotonic Agents; Digoxin; Dose-Response Relationship, Drug; Enzyme Activation; Hippocampus; In Vitro Techniques; Neuroprotective Agents; Ouabain; Rats; Sodium-Potassium-Exchanging ATPase

The present study was designed to investigate the possible neuroprotective effect of digoxin induced pharmacological preconditioning (PP) and its probable mechanism. Bilateral carotid artery occlusion (BCAO) of 17 min followed by reperfusion for 24 h was employed to produce ischemia and reperfusion (I/R) induced cerebral injury in male swiss albino mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using elevated plus maze test. Degree of motor incoordination was evaluated using inclined beam walking test, rota rod test and lateral push test. Digoxin (0.08 mg/kg, i.p.) was administered 24 h before surgery in a separate group of animals to induce PP. BCAO followed by reperfusion, produced significant rise in cerebral infarct size along with impairment of memory and motor coordination. Digoxin treatment produced a significant decrease in cerebral infarct size and reversal of I/R induced impairment of memory and motor incoordination. Digoxin induced neuroprotective effect was abolished significantly by verapamil (15 mg/kg, i.p.), a L-type calcium channel blocker, ruthenium red (3 mg/kg, s.c.), an intracellular ryanodine receptor blocker and 3,4-dichlorobenzamil (Na(+)/Ca(2+) exchanger inhibitor). These findings indicate that digoxin preconditioning exerts a marked neuroprotective effect on the ischemic brain, which is possibly linked to digitalis induced increase in intracellular calcium levels eventually leading to the activation of calcium sensitive signal transduction cascades.

Topics: Amiloride; Animals; Brain; Brain Ischemia; Calcium; Calcium Signaling; Digoxin; Male; Memory; Mice; Neuroprotective Agents; Psychomotor Performance; Reperfusion Injury; Ruthenium Red; Verapamil