AM‐36 modulates the neutrophil inflammatory response and reduces breakdown of the blood brain barrier after endothelin‐1 induced focal brain ischaemia

Abstract

Background and purpose: Following transient focal stroke, rapid accumulation and activation of neutrophils in the ischaemic region is deleterious due to release of reactive oxygen species and myeloperoxidase (MPO). The purpose of this study was to examine whether AM-36, both a Na þ channel blocker and an antioxidant, afforded neuroprotection by modulating neutrophil accumulation into brain, following endothelin-1 (ET-1) induced middle cerebral artery occlusion (MCAo) in conscious rats. Experimental approach: AM-36 was administered at 3 and 24 h after ET-1-induced MCAo. Functional recovery was determined using grid-walking and cylinder tests. Image analysis of brain sections was used to determine infarct volume. The effect of AM-36 on neutrophil infiltration and their interaction with macrophages was examined in rats at 48 h following MCAo by both an MPO assay and double-label immunofluorescence. Blood brain barrier (BBB) breakdown was measured by the area stained by intravenous Evans Blue. Key results: AM-36 reduced functional deficits in both tests such that no difference existed from pre-ischaemic values at 48 h. Neutrophil infiltration, assessed by MPO activity, and infarct volume were significantly reduced following AM-36 administration by 54 and 60% respectively. Similarly, immunofluorescence revealed that AM-36 reduced neutrophil infiltration by B50% in selected brain regions, when compared to controls, and also modulated macrophage phagocytosis of neutrophils. Breakdown of the BBB was significantly reduced by 60% following AM-36 treatment. Conclusions and Implications: These findings suggest that AM-36 can directly modulate the neutrophil inflammatory response and reduce BBB breakdown following MCAo.

Tracking the inflammatory response in stroke in vivo by sensing the enzyme myeloperoxidase

“…could reduce MPO activity and improve functional outcome after stroke in mouse models (22). Furthermore, the long-lasting increased MPO expression Ͼ3 weeks found in our study suggests that inflammation plays a role in cerebral ischemia well into the late subacute stage.…”

Osthole, a Natural Coumarin Improves Cognitive Impairments and BBB Dysfunction After Transient Global Brain Ischemia in C57 BL/6J Mice: Involvement of Nrf2 Pathway

“…This function can be disrupted under a variety of pathological conditions, including ischemic stroke [15]. Recently, researchers have recognized that protecting the cerebral microcirculation, especially maintaining the integrity of BBB should be important targets of experimental therapy in cerebral ischemia [30]. Reportedly, Fig.…”

Pharmacokinetics and brain uptake of AM-36, a novel neuroprotective agent, following intravenous administration to rats

“…In order to support the observed in-vivo neuropharmacological effects of AM-36 following administration to rodents 2000;2003;2004;Weston et al 2006), the plasma pharmacokinetics and brain uptake of this compound were assessed following i.v. administration to rats.…”

“…AM-36 is neuroprotective when administered up to 3 h after endothelin-1 induced middle cerebral artery occlusion, reducing both cortical and striatal damage . In addition to improving functional deficits in this stroke model, more recently AM-36 has been shown to directly modulate the neutrophil inflammatory response and to reduce BBB breakdown following an ischaemic attack (Weston et al 2006). While there has been extensive pharmacological assessment of this novel compound for the treatment of stroke, there have been no reports on the plasma pharmacokinetics of this compound following administration to animals used in preclinical drug development.…”