Donepezil, Anti-Alzheimer's Disease Drug, Prevents Cardiac Rupture during Acute Phase of Myocardial Infarction in Mice

Background: We have previously demonstrated that the chronic intervention in the cholinergic system by donepezil, an acetylcholinesterase inhibitor, plays a beneficial role in suppressing long-term cardiac remodeling after myocardial infarction (MI). In comparison with such a chronic effect, however, the acute effect of donepezil during an acute phase of MI remains unclear. Noticing recent findings of a cholinergic mechanism for anti-inflammatory actions, we tested the hypothesis that donepezil attenuates an acute inflammatory tissue injury following MI. Methods and Results: In isolated and activated macrophages, donepezil significantly reduced intra- and extracellular matrix metalloproteinase-9 (MMP-9). In mice with MI, despite the comparable values of heart rate and blood pressure, the donepezil-treated group showed a significantly lower incidence of cardiac rupture than the untreated group during the acute phase of MI. Immunohistochemistry revealed that MMP-9 was localized at the infarct area where a large number of inflammatory cells including macrophages infiltrated, and the expression and the enzymatic activity of MMP-9 at the left ventricular infarct area was significantly reduced in the donepezil-treated group. Conclusion: The present study suggests that donepezil inhibits the MMP-9-related acute inflammatory tissue injury in the infarcted myocardium, thereby reduces the risk of left ventricular free wall rupture during the acute phase of MI

Undifferentiated and differentiated PC12 cells protected by huprines against injury induced by hydrogen peroxide

Oxidative stress is implicated in the pathogenesis of neurodegenerative disorders and hydrogen peroxide (H2O2) plays a central role in the stress. Huprines, a group of potent acetylcholinesterase inhibitors (AChEIs), have shown a broad cholinergic pharmacological profile. Recently, it has been observed that huprine X (HX) improves cognition in non transgenic middle aged mice and shows a neuroprotective activity (increased synaptophysin expression) in 3xTg-AD mice. Consequently, in the present experiments the potential neuroprotective effect of huprines (HX, HY, HZ) has been analyzed in two different in vitro conditions: undifferentiated and NGF-differentiated PC12 cells. Cells were subjected to oxidative insult (H2O2, 200 µM) and the protective effects of HX, HY and HZ (0.01 µM- 1 µM) were analyzed after a pre-incubation period of 24 and 48 hours. All huprines showed protective effects in both undifferentiated and NGF-differentiated cells, however only in differentiated cells the effect was dependent on cholinergic receptors as atropine (muscarinic antagonist, 0.1 µM) and mecamylamine (nicotinic antagonist, 100 µM) reverted the neuroprotection action of huprines. The decrease in SOD activity observed after oxidative insult was overcome in the presence of huprines and this effect was not mediated by muscarinic or nicotinic receptors. In conclusion, huprines displayed neuroprotective properties as previously observed in in vivo studies. In addition, these effects were mediated by cholinergic receptors only in differentiated cells. However, a non-cholinergic mechanism, probably through an increase in SOD activity, seems to be also involved in the neuroprotective effects of huprines

Activation of Alpha-7 Nicotinic Acetylcholine Receptor Reduces Brain Edema in Mice with Ischemic Stroke and Bone Fracture

Stroke is an important risk factor for bone fracture. We showed previously that bone fracture at the acute stage of ischemic stroke worsens, and activation of α-7 nicotinic acetylcholine receptor (α-7 nAchR) improves, stroke recovery by attenuating inflammation. We hypothesized that activation of α-7 nAchR also improves the blood-brain barrier (BBB) integrity. Permanent distal middle cerebral artery occlusion (pMCAO) was performed on C57BL/6J mice followed by tibia fracture 1 day later. Mice were treated with 0.8 mg/kg PHA 568487 (PHA, α-7 nAchR-specific agonist), 6 mg/kg methyllycaconitine (MLA, α-7 nAchR antagonist), or saline 1 and 2 days after pMCAO. Brain water content, the expression of monoamine oxidase B (MAO-B), and tight junction protein (claudin-5) were assessed. We found that tibia fracture increased water content in the ischemic stroke brain (p = 0.006) and MAO-B-positive astrocytes (p < 0.001). PHA treatment reduced water content and MAO-B-positive astrocytes and increased claudin-5 expression in stroke and stroke + tibia fracture mice (p < 0.05), while MLA had the opposite effect. Our findings suggest that in addition to inhibiting inflammation, activation of α-7 nAchR also reduces brain edema, possibly through diminished astrocyte oxidative stress and improved BBB integrity. Thus, the α-7 nAchR-specific agonist could be developed into a new therapy for improving recovery of patients with stroke or stroke + bone fracture