α7 Nicotinic acetylcholine receptor agonist attenuates neuropathological changes associated with intracerebral hemorrhage in mice.
ABSTRACT We have demonstrated previously that nicotine affords neuroprotective and anti-inflammatory effects against intracerebral hemorrhage (ICH)-associated neuropathological changes. The present study was undertaken to clarify whether subtype-specific agonists of nicotinic acetylcholine receptors (nAChRs) could preserve tissue integrity in mouse ICH model in vivo. ICH was induced by unilateral injection of collagenase into the striatum of male C57BL/6 mice. Daily intraperitoneal injection of α7 nAChR agonist PNU-282987 (3-10mg/kg) for 3 days, starting from 3h after induction of ICH, significantly increased the number of surviving neurons in the central and the peripheral regions of hematoma at 3 days after ICH. In contrast, α4β2 nAChR agonist RJR-2403 (2-10 mg/kg) given in the same regimen showed no significant effect. PNU-282987 and RJR-2403 did not affect either the size of hemorrhage or the extent of brain edema associated with ICH. PNU-282987 decreased the number of activated microglia/macrophages accumulating in the perihematoma region at 3 days after ICH, in a dose-dependent manner. On the other hand, the number of microglia/macrophages in the central region of hematoma at early phase of pathology (6 h after ICH) was increased by 10mg/kg PNU-282987. These results suggest that α7 nAChR agonist can provide neuroprotective effect on ICH-induced injury, independently of its anti-inflammatory actions.
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ABSTRACT: BACKGROUND AND PURPOSE: Blood-brain barrier disruption and consequent vasogenic edema formation codetermine the clinical course of intracerebral hemorrhage (ICH). This study examined the effect of PHA-543613, a novel α7 nicotinic acetylcholine receptor agonist, on blood-brain barrier preservation after ICH. METHODS: Male CD-1 mice, subjected to intrastriatal blood infusion, received PHA-543613 alone or in combination with α7 nicotinic acetylcholine receptor antagonist methyllycaconitine or phosphatidylinositol 3-kinase inhibitor wortmannin. RESULTS: PHA-543613 alone, but not in combination with methyllycaconitine or wortmannin, inhibited glycogen synthase kinase-3β, thus, stabilizing β-catenin and tight junction proteins, which was paralleled by improved blood-brain barrier stability and ameliorated neurofunctional deficits in ICH animals. CONCLUSIONS: PHA-543613 preserved blood-brain barrier integrity after ICH, possibly through phosphatidylinositol 3-kinase-Akt-induced inhibition of glycogen synthase kinase-3β and β-catenin stabilization.Stroke 04/2013; 44(6). DOI:10.1161/STROKEAHA.111.000427 · 6.02 Impact Factor
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ABSTRACT: Intracerebral hemorrhage (ICH) is the most deadly and least treatable subtype of stroke, and at the present time there are no evidence-based therapeutic interventions for patients with this disease. Secondary injury mechanisms are known to cause substantial rates of morbidity and mortality following ICH, and the inflammatory cascade is a major contributor to this post-ICH secondary injury. The alpha-7 nicotinic acetylcholine receptor (α7-nAChR) agonists have a well-established antiinflammatory effect and have been shown to attenuate perihematomal edema volume and to improve functional outcome in experimental ICH. The authors evaluate the current evidence for the use of an α7-nAChR agonist as a novel therapeutic agent in patients with ICH.Neurosurgical FOCUS 05/2013; 34(5):E10. DOI:10.3171/2013.2.FOCUS1315 · 2.14 Impact Factor
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ABSTRACT: Clinical studies have reported that the nicotinic receptor agonist varenicline improves balance and coordination in patients with several types of ataxia, but confirmation in an animal model has not been demonstrated. This study investigated whether varenicline and nicotine could attenuate the ataxia induced in rats following destruction of the olivocerebellar pathway by the neurotoxin 3-acetylpyridine (3-AP). The administration of 3-AP (70 mg/kg followed by 300 mg niacinamide/kg; i.p.) led to an 85% loss of inferior olivary neurons within one week without evidence of recovery, and was accompanied by a 72% decrease in rotorod activity, a 3-fold increase in the time to traverse a stationary beam, a 19% decrease in velocity and 31% decrease in distance moved in the open field, and alterations in gait parameters, with a 19% increase in hindpaw stride width. The daily administration of nicotine (0.33 mg free base/kg) for one week improved rotorod performance by 50% and normalized the increased hindpaw stride width, effects that were prevented by the daily preadministration of the nicotinic antagonist mecamylamine (0.8 mg free base/kg). Varenicline (1 and 3 mg free base/kg daily) also improved rotorod performance by approximately 50% following one week of administration, but did not alter performance on the beam. Neither varenicline nor nicotine, at doses that improved balance, affected impaired locomotor activity in the open field. Results provide evidence that nicotinic agonists are of benefit for alleviating some of the behavioral deficits in olivocerebellar ataxia and warrant further studies to elucidate the specific mechanism(s) involved.Neuropharmacology 05/2013; 73. DOI:10.1016/j.neuropharm.2013.05.016 · 4.82 Impact Factor