cytochrome-c-t and Subarachnoid-Hemorrhage

(-)-Epigallocatechin-3-gallate (EGCG), the main bioactive component of tea catechins, exhibits broad-spectrum health efficacy against mitochondrial damage after subarachnoid hemorrhage (SAH). The mechanisms, however, are largely unknown. Here, the ability of EGCG to rescue mitochondrial dysfunction and mitochondrial dynamics following the inhibition of cell death was investigated by using in vitro and in vivo SAH models. EGCG blocked the cytosolic channel ([Ca2+])i influx via voltage-gated calcium channels (VGCCs), which induced mitochondrial dysfunction, including mitochondrial membrane potential depolarization and reactive oxygen species (ROS) release. As expected, EGCG ameliorated oxyhemoglobin (OxyHb)-induced impairment of mitochondrial dynamics by regulating the expression of Drp1, Fis1, OPA1, Mfn1, and Mfn2. As a result, EGCG restored the increases in fragmented mitochondria and the mtDNA copy number in the OxyHb group to almost the normal level after SAH. In addition, the normal autophagic flux induced by EGCG at both the initiation and formation stages regulated Atg5 and Beclin-1 after SAH for the timely elimination of damaged mitochondria. In the end, EGCG increased the neurological score by decreasing cell death through the cyt c-mediated intrinsic apoptotic pathway. The results revealed the mechanisms behind the neuroprotective effects of EGCG via inhibition of the overloaded [Ca2+]i-induced mitochondrial dysfunction and the imbalanced mitochondrial fusion and fission cycle. Therefore, the simultaneous inhibition and timely elimination of damaged mitochondria could determine the therapeutic effect of EGCG.

Topics: Animals; Apoptosis; Autophagy; Catechin; Cytochromes c; Humans; Male; Mice; Mitochondria; Mitochondrial Dynamics; Neuroprotective Agents; Oxidative Stress; Reactive Oxygen Species; Subarachnoid Hemorrhage

Previous studies have shown that mitochondrial Ca(2+) is undertaken by mitochondrial calcium uniporter (MCU), and its accumulation is associated with the development of many diseases. However, little was known about the role of MCU in early brain injury (EBI) after subarachnoid hemorrhage (SAH). MCU can be opened by spermine under a physiological condition and inhibited by ruthenium red (RR). Herein, we investigated the effects of RR and spermine to reveal the role of MCU in SAH animal model. The data obtained with biochemical and histological assays showed that mitochondrial Ca(2+) concentration was significantly increased in the temporal cortex of rats 1, 2, and 3 days after SAH, consistent with constant high levels of cellular Ca(2+) concentration. In agreement with the observation in the acute phase, SAH rats showed an obvious increase of reactive oxygen species (ROS) level and decrease of ATP production. Blockage of MCU prevented Ca(2+) accumulation, abated the level of oxidative stress, and improved the energy supply. Translocation of cytochrome c, increased cleaved caspase-3, and a large amount of apoptotic cells after SAH were reversed by RR administration. Surprisingly, exogenous spermine did not increase cellular Ca(2+) concentration, but lessened the Ca(2+) accumulation after SAH to benefit the rats. Taken together, our results demonstrated that blockage of MCU or prevention of Ca(2+) accumulation after SAH is essential in EBI after SAH. These findings suggest that MCU is considered to be a therapeutic target for patients suffering from SAH.

Topics: Animals; Brain Injuries; Calcium; Calcium Channels; Cytochromes c; Disease Models, Animal; Male; Mitochondria; Rats, Sprague-Dawley; Reactive Oxygen Species; Subarachnoid Hemorrhage; Time Factors

Melatonin is a strong antioxidant that has beneficial effects against early brain injury (EBI) following a subarachnoid hemorrhage (SAH) in rats; protection includes reduced mortality and brain water content. The molecular mechanisms underlying these clinical effects in the SAH model, however, have not been clearly identified. This study was undertaken to determine the influence of melatonin on neural apoptosis and the potential mechanism of these effects in EBI following SAH using the filament perforation model of SAH in male Sprague Dawley rats. Melatonin (150 mg/kg) or vehicle was given via an intraperitoneal injection 2 hr after SAH induction. Brain samples were extracted 24 hr after SAH. The results show that melatonin treatment markedly reduced caspase-3 activity and the number of TUNEL-positive cells, while the treatment increased the LC3-II/LC3-I, an autophagy marker, which indicated that melatonin-enhanced autophagy ameliorated apoptotic cell death in rats subjected to SAH. To further identify the mechanism of autophagy protection, we demonstrated that melatonin administration reduced Bax translocation to the mitochondria and the release of cytochrome c into the cytosol. Taken together, this report demonstrates that melatonin improved the neurological outcome in rats by protecting against neural apoptosis after the induction of filament perforation SAH; moreover, the mechanism of these antiapoptosis effects was related to the enhancement of autophagy, which ameliorated cell apoptosis via a mitochondrial pathway.

Topics: Analysis of Variance; Animals; Apoptosis; Autophagy; bcl-2-Associated X Protein; Brain Injuries; Cytochromes c; In Situ Nick-End Labeling; Male; Melatonin; Mitochondria; Rats; Rats, Sprague-Dawley; Subarachnoid Hemorrhage

Tea polyphenols are of great benefit to the treatment of several neurodegenerative diseases. In order to explore the neuroprotective effects of tea polyphenols and their potential mechanisms, an established in vivo subarachnoid hemorrhage (SAH) model was used and alterations of mitochondrial function, ATP content, and cytochrome c (cyt c) in cerebral cortex were detected. This study showed that the alteration of mitochondrial membrane potential was an early event in SAH progression. The trend of ATP production was similar to that of mitochondrial membrane potential, indicating that the lower the mitochondrial membrane potential, lesser the ATP produced. Due to mitochondrial dysfunction, more cyt c was released in the SAH group. Interestingly, the preadministration of tea polyphenols significantly rescued the mitochondrial membrane potential to basal level, as well as the ATP content and the cyt c level in the brain cortex 12 h after SAH. After pretreatment with tea polyphenols, the neurological outcome was also improved. The results provide strong evidence that tea polyphenols enhance neuroprotective effects by inhibiting polarization of mitochondrial membrane potential, increasing ATP content, and blocking cyt c release.

Topics: Adenosine Triphosphate; Animals; Brain Injuries; Cerebral Cortex; Cytochromes c; Membrane Potential, Mitochondrial; Mice; Neuroprotective Agents; Oxyhemoglobins; Polyphenols; Subarachnoid Hemorrhage; Tea