Increased Acetylocholin Protects Against Ischemic Cerebral Injury

OBJECTIVEStroke makes a considerable contribution to morbidity and mortality, and increases the burdent of society. So the prevention is an important public health concern to curb the stroke pandemicly. Many other ways are needed to be researched and used for the prevention and therapy for ischemic stroke.Recent studies suggest that the parasympathetic nervous system, in particular the efferent vagus nerve, regulates immune responses via the peripheral release of acetylcholine (ACh). The present work is designed to investigate whether increased acetylcholine (ACh) protects against stroke.METHODSThe study was based on the model of middle cerebral arterial occlusion (MCAO)-induced ischemic cerebral injury in rodents. Sprague-Dawley (SD) rats and mice was administered with nestigmine15minutes before MCAO. The injury of MCAO was determinated by neurological deficits and the infarct size.Neurological deficits were examined using a5-point scale. Animals with normal motor function were scored as0, flexion of the contralateral torso and forearm on lifting the animal by the tail as1, circling to the contralateral side but normal posture at rest as2, leaning to the contralateral side as3, and no spontaneous motor activity as4. Brain slices (six for mice; seven for rats) were prepared with brain-cutting matrix. The slices were incubated in1%TTC solution at37℃for30minutes, and then mounted on dry paper and photographed with a digital camera. The infarct size and hemisphere size of each section were traced and quantified with ImageJ software. Interference by edema was corrected by a standard protocol (contralateral hemisphere area-area of nonischemic ipsilateral hemisphere). Infarct size is expressed as a percentage of the contralateral hemisphere.RESULTS1. Neostigmine (40μg/kg) has significantly decreased the ischemic area of hemisphere, suggesting that the cholinesterase inhibitor neostigmine has protective effect on ischemic stroke.2. Compared with the control group, neostigmine (40μg/kg) significantly inhibited the apoptosis induced by MCAO in SD rats.3. Compared with the control group, neostigmine (40μg/kg) significantly reduced the release of proinflammatory cytokines induced by MCAO in SD rats. The levels of IL-6and TNF-α were significantly decreased.4. Neostigmine (40μg/kg) significantly decreased the ischemic area of hemisphere.The protect effect is much better when adding anisodamine (20mg/kg) while the protect effect is nearly abolished when adding N-Receptor antagonist vecuronim bromide (400μg/kg).5. Neostigmine (80μg/kg) significantly decreased the infarct size and improved the neurological funtion in a7nAChR wild-type mice but not in knock out mice.CONCLUSIONSIncreased ACh by the cholinesterase inhibitor neostigmine has protective effect on ischemic stroke, which is depended on a7nAChR. These findings indicate that the ACh-a7nAChR pathway might be a new strategy for ischemic stroke.