g(m1)-ganglioside and Infarction--Middle-Cerebral-Artery

Ganglioside GM1, which is particularly abundant in the central nervous system (CNS), is closely associated with the protection against several CNS disorders. However, controversial findings have been reported on the role of GM1 following ischemic stroke. In the present study, using a rat middle cerebral artery occlusion (MCAO) model, we investigated whether GM1 can protect against ischemic brain injury and whether it targets the autophagy pathway. GM1 was delivered to Sprague-Dawley male rats at 3 doses (25 mg/kg, 50 mg/kg, 100 mg/kg) by intraperitoneal injection soon after reperfusion and then once daily for 2 days. The same volume of saline was given as a control. Tat-Beclin-1, a specific autophagy inducer, was administered by intraperitoneal injection at 24 and 48 hours post-MCAO. Infarction volume, mortality and neurological function were assessed at 72 hours after ischemic insult. Immunofluorescence and Western blotting were performed to determine the expression of autophagy-related proteins P62, LC3 and Beclin-1 in the penumbra area. No significant changes in mortality and physiological variables (heart rate, blood glucose levels and arterial blood gases) were observed between the different groups. However, MCAO resulted in enhanced conversion of LC3-I into LC3-II, P62 degradation, high levels of Beclin-1, a large area infarction (26.3±3.6%) and serious neurobehavioral deficits. GM1 (50 mg/kg) treatment significantly reduced the autophagy activation, neurobehavioral dysfunctions, and infarction volume (from 26.3% to 19.5%) without causing significant adverse side effects. However, this biological function could be abolished by Tat-Beclin-1.. GM1 demonstrated safe and robust neuroprotective effects that are associated with the inhibition of autophagy following experimental stroke.

Topics: Animals; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Brain; Brain Ischemia; Disease Models, Animal; Drug Administration Schedule; G(M1) Ganglioside; Gene Expression Regulation; Gene Products, tat; Heat-Shock Proteins; Infarction, Middle Cerebral Artery; Injections, Intraperitoneal; Male; Microtubule-Associated Proteins; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins; Sequestosome-1 Protein; Signal Transduction; Stroke; Survival Analysis

Neuronal damage subsequent to transient cerebral ischemia is a multifactorial process involving several overlapping mechanisms. Gangliosides, sialic acid-conjugated glycosphingolipids, reduce the severity of acute brain damage in vitro. However their in vivo effects on the cerebral cortex damaged by ischemic infarct are unknown. To assess the possible protective role of gangliosides we examined their expression in the cerebral cortex damaged by ischemic infarct in the rat. Ischemia was induced by middle cerebral artery (MCA) occlusion, and the resulting damage was observed by staining with 2, 3, 5-triphenylterazolium chloride (TTC). High-performance thin-layer chromatography (HPTLC) showed that gangliosides GM3 and GM1 increased in the damaged cerebral cortex, and immunofluorescence microscopy also revealed a significant change in expression of GM1. In addition, in situ hybridization demonstrated an increase in the mRNA for ganglioside GM3 synthase. These results suggest that gangliosides GM1 and GM3 may be synthesized in vivo to protect the cerebral cortex from ischemic damage.

Topics: Animals; Brain Ischemia; Cerebral Cortex; Chromatography, Thin Layer; G(M1) Ganglioside; G(M3) Ganglioside; In Situ Hybridization; Infarction, Middle Cerebral Artery; Microscopy, Fluorescence; Middle Cerebral Artery; Rats; Rats, Wistar; Sialyltransferases; Tetrazolium Salts