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Phlorofucofuroeckol Improves Glutamate-Induced Neurotoxicity through Modulation of Oxidative Stress-Mediated Mitochondrial Dysfunction in PC12 Cells

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ABSTRACT

Stroke is a complex neurodegenerative disorder with a clinically high prevalence and mortality. Despite many efforts to protect against ischemic stroke, its incidence and related permanent disabilities continue to increase. In this study, we found that pretreatment with phlorofucofuroeckol (PFF), isolated from brown algae species, significantly increased cell viability in glutamate-stimulated PC12 cells. Additionally, glutamate-stimulated cells showed irregular morphology, but PFF pretreatment resulted in improved cell morphology, which resembled that in cells cultured under normal conditions. We further showed that PFF pretreatment effectively inhibited glutamate-induced apoptotic cell death in a caspase-dependent manner. Reactive oxygen species (ROS) induced by oxidative stress are closely associated with ischemia-induced neurological diseases. Exposure of PC12 cells to glutamate induced abundant production of intracellular ROS and mitochondrial dysfunction, which was attenuated by PFF in a dose-dependent manner. In vivo studies revealed that PFF-mediated prevention was achieved predominantly through inhibition of apoptosis and mitochondrial ROS generation. Taken together, these results suggest the possibility of PFF as a neuroprotective agent in ischemic stroke.

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PFF treatment prevented MCAO-induced brain damage in a rat animal model of ischemic stroke.(A) In vivo experimental schedule. PFF was injected intracerebroventricularly into the left lateral cerebral ventricle of the rat, as described in the Materials and Methods section. (B and C) TTC staining was used to assess infarction volume in coronal sections. (B) Representative images of coronal sections from rats receiving sham, MCAO, and PFF plus MCAO on day 5. The red region indicates intact tissue, and the white region indicates the infarct area. (C) The bar graph represents the means ± SD of infarct volume under each condition. (D and E) Histological changes in the hippocampus were observed using cresyl violet staining. (D) Representative images of each section. Scale bars = 25 μm. (E) Cell viability was determined in tissue sections from each rat group. ***p < 0.001 vs. the control group.
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pone.0163433.g006: PFF treatment prevented MCAO-induced brain damage in a rat animal model of ischemic stroke.(A) In vivo experimental schedule. PFF was injected intracerebroventricularly into the left lateral cerebral ventricle of the rat, as described in the Materials and Methods section. (B and C) TTC staining was used to assess infarction volume in coronal sections. (B) Representative images of coronal sections from rats receiving sham, MCAO, and PFF plus MCAO on day 5. The red region indicates intact tissue, and the white region indicates the infarct area. (C) The bar graph represents the means ± SD of infarct volume under each condition. (D and E) Histological changes in the hippocampus were observed using cresyl violet staining. (D) Representative images of each section. Scale bars = 25 μm. (E) Cell viability was determined in tissue sections from each rat group. ***p < 0.001 vs. the control group.

Mentions: Although there are several experimental in vivo stroke models in various species, including rodents, cats, canines, and even primates, the middle cerebral artery occlusion (MCAO) model is well known as a usable experimental focal cerebral ischemia model in rodents [35]. To evaluate the in vivo protective effects of PFF, PFF was administered intracerebroventricularly (ICV) three times for 3 consecutive days before ischemia/reperfusion, as described in Fig 6A. When compared with those of the sham group, the coronal infarct volumes of the rats receiving ischemia/reperfusion were greatly increased; however, these were significantly decreased, by about 72% (p < 0.001), in the PFF-administered rats (Fig 6B and 6C). Moreover, we used histological staining, with hematoxylin and eosin (H&E), to evaluate the cellular responses against focal ischemic brain injury associated with PFF administration (Fig 6D and 6E). The brain tissues suffering ischemia/reperfusion showed severe neuronal damage, such as neuronal shrinkage, apoptotic tissue injury, and increased nuclear basophilia; however, these phenotypes were effectively diminished in rats administered PFF. These results indicated that local ICV injection of PFF significantly reduced infarct volume and severe cellular responses in vivo in a MCAO model.


Phlorofucofuroeckol Improves Glutamate-Induced Neurotoxicity through Modulation of Oxidative Stress-Mediated Mitochondrial Dysfunction in PC12 Cells
PFF treatment prevented MCAO-induced brain damage in a rat animal model of ischemic stroke.(A) In vivo experimental schedule. PFF was injected intracerebroventricularly into the left lateral cerebral ventricle of the rat, as described in the Materials and Methods section. (B and C) TTC staining was used to assess infarction volume in coronal sections. (B) Representative images of coronal sections from rats receiving sham, MCAO, and PFF plus MCAO on day 5. The red region indicates intact tissue, and the white region indicates the infarct area. (C) The bar graph represents the means ± SD of infarct volume under each condition. (D and E) Histological changes in the hippocampus were observed using cresyl violet staining. (D) Representative images of each section. Scale bars = 25 μm. (E) Cell viability was determined in tissue sections from each rat group. ***p < 0.001 vs. the control group.
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pone.0163433.g006: PFF treatment prevented MCAO-induced brain damage in a rat animal model of ischemic stroke.(A) In vivo experimental schedule. PFF was injected intracerebroventricularly into the left lateral cerebral ventricle of the rat, as described in the Materials and Methods section. (B and C) TTC staining was used to assess infarction volume in coronal sections. (B) Representative images of coronal sections from rats receiving sham, MCAO, and PFF plus MCAO on day 5. The red region indicates intact tissue, and the white region indicates the infarct area. (C) The bar graph represents the means ± SD of infarct volume under each condition. (D and E) Histological changes in the hippocampus were observed using cresyl violet staining. (D) Representative images of each section. Scale bars = 25 μm. (E) Cell viability was determined in tissue sections from each rat group. ***p < 0.001 vs. the control group.
Mentions: Although there are several experimental in vivo stroke models in various species, including rodents, cats, canines, and even primates, the middle cerebral artery occlusion (MCAO) model is well known as a usable experimental focal cerebral ischemia model in rodents [35]. To evaluate the in vivo protective effects of PFF, PFF was administered intracerebroventricularly (ICV) three times for 3 consecutive days before ischemia/reperfusion, as described in Fig 6A. When compared with those of the sham group, the coronal infarct volumes of the rats receiving ischemia/reperfusion were greatly increased; however, these were significantly decreased, by about 72% (p < 0.001), in the PFF-administered rats (Fig 6B and 6C). Moreover, we used histological staining, with hematoxylin and eosin (H&E), to evaluate the cellular responses against focal ischemic brain injury associated with PFF administration (Fig 6D and 6E). The brain tissues suffering ischemia/reperfusion showed severe neuronal damage, such as neuronal shrinkage, apoptotic tissue injury, and increased nuclear basophilia; however, these phenotypes were effectively diminished in rats administered PFF. These results indicated that local ICV injection of PFF significantly reduced infarct volume and severe cellular responses in vivo in a MCAO model.

View Article: PubMed Central - PubMed

ABSTRACT

Stroke is a complex neurodegenerative disorder with a clinically high prevalence and mortality. Despite many efforts to protect against ischemic stroke, its incidence and related permanent disabilities continue to increase. In this study, we found that pretreatment with phlorofucofuroeckol (PFF), isolated from brown algae species, significantly increased cell viability in glutamate-stimulated PC12 cells. Additionally, glutamate-stimulated cells showed irregular morphology, but PFF pretreatment resulted in improved cell morphology, which resembled that in cells cultured under normal conditions. We further showed that PFF pretreatment effectively inhibited glutamate-induced apoptotic cell death in a caspase-dependent manner. Reactive oxygen species (ROS) induced by oxidative stress are closely associated with ischemia-induced neurological diseases. Exposure of PC12 cells to glutamate induced abundant production of intracellular ROS and mitochondrial dysfunction, which was attenuated by PFF in a dose-dependent manner. In vivo studies revealed that PFF-mediated prevention was achieved predominantly through inhibition of apoptosis and mitochondrial ROS generation. Taken together, these results suggest the possibility of PFF as a neuroprotective agent in ischemic stroke.

No MeSH data available.


Related in: MedlinePlus