Antioxidants: The new frontier for translational research in cerebroprotection

The effects of astaxanthin supplementation on liver enzyme levels

According to previous studies, astaxanthin exerts various biological effects due to its anti-inflammatory and antioxidant capabilities; however, its effects on liver enzymes have not yet been well elucidated. Therefore, we conducted a meta-analysis to assess astaxanthin's effects on liver enzymes. A systematic literature search was conducted using scientific databases including PubMed, Scopus, Web of Science, the Cochrane databases, and Google Scholar up to February 2023 to find relevant randomized controlled trials (RCTs) examining the effects of astaxanthin supplementation on alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transferase (GGT), and alkaline phosphatase (ALP). A random-effects model was used for the estimation of the pooled weighted mean difference (WMD). Overall, we included five trials involving 196 subjects. The duration of the intervention was between 4 and 48 weeks, and the dose was between 6 and 12 mg/day. ALT levels increased in the intervention group compared to the control group following astaxanthin supplementation (WMD: 1.92 U/L, 95% CI: 0.16 to 3.68, P=0.03), whereas supplementation with astaxanthin had a non-significant effect on AST (WMD: 0.72 U/L, 95% CI: -0.85 to 2.29, P=0.36), GGT (WMD: 0.48 U/L, 95% CI: -2.71 to 3.67, P=0.76), and ALP levels (WMD: 2.85 U/L, 95% CI: -7.94 to 13.63, P=0.60) compared to the placebo group. Our data showed that astaxanthin supplementation increases ALT concentrations in adults without affecting the levels of other liver enzymes. Further long-term and well-designed RCTs are necessary to assess and confirm these findings.

Clinical Evidence of Acetyl-L-Carnitine Efficacy in the Treatment of Acute Ischemic Stroke: A Pilot Clinical Trial

Background. This study was undertaken to evaluate the influence of oral Acetyl-L-carnitine (ALC) in patients with acute ischemic stroke. Methods. Sixty-nine cases with acute ischemic stroke with the onset of symptoms less than 24 hours not candidates for reperfusion therapy were randomly assigned to either the ALC group (1000 mg three times per day for three consecutive days) or the matching placebo group. The study outcomes based on intention-to-treat criteria included the change in the modified Rankin Scale (mRS) and National Institutes of Health Stroke Scale (NIHSS) score from baseline to day 90, as well as the change in serum levels of the inflammatory and oxidative stress biomarkers over the 3-day treatment protocol. Results. The NIHSS score and mRS score on day 90 were improved by 5.82 and 0.94 scores, respectively, in the ALC-treated group compared to 2.83 and 0.11 scores, respectively, in the placebo-treated group, which demonstrated the superiority of ALC relative to placebo. By using the multivariable analysis after adjusting for other variables in the model, compared to the group treated with placebo, patients in the ALC group had lower NIHSS score ( $\beta$ : -2.40, 95% CI: -0.69, -4.10 ( $p=0.007$ )) and mRS score ( $\beta$ : -1.18, 95% CI: -0.52, -1.84 ( $p=0.001$ )) 90 days after the intervention. The percentage of patients with a favourable functional outcome at day 90, defined as mRS scores of 0 or 1, was significantly higher in the ALC group in comparison to the placebo group (52.9% versus 28.6%). Further, over the 3-day treatment protocol, in the patients receiving ALC, the serum levels of proinflammatory biomarkers, including soluble intercellular adhesion molecule-1 (sICAM-1), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and neuron-specific enolase (NSE), showed a significant decrease, while the serum levels of antioxidant biomarkers, including glutathione peroxidase (GPx), superoxide dismutase (SOD), and total antioxidant capacity (TAC), as well as the total L-carnitine’s level showed a significant increase compared to those in patients receiving placebo indicating significant alteration. Conclusions. Although preliminary, these results suggested that ALC administration during the acute phase of ischemic stroke might be helpful in improving functional and neurological outcomes that are probably linked to its anti-inflammatory and antioxidant properties. Trial Registration. This trial is registered with IRCT20150629022965N17 at Iranian Registry of Clinical Trials (registration date: 25/07/2018).

Rescuing mitochondria in traumatic brain injury and intracerebral hemorrhages - A potential therapeutic approach

Mitochondria are dynamic organelles responsible for cellular energy production. Besides, regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, signal transmission, and the fate of cellular survival in case of injury and pathologies. Accumulating reports have suggested multiple roles of mitochondria in neuropathologies, neurodegeneration, and immune activation under physiological and pathological conditions. Mitochondrial dysfunction, which occurs at the initial phase of brain injury, involves oxidative stress, inflammation, deficits in mitochondrial bioenergetics, biogenesis, transport, and autophagy. Thus, development of targeted therapeutics to protect mitochondria may improve functional outcomes following traumatic brain injury (TBI) and intracerebral hemorrhages (ICH). In this review, we summarize mitochondrial dysfunction related to TBI and ICH, including the mechanisms involved, and discuss therapeutic approaches with special emphasis on past and current clinical trials.

Sestrins at the Interface of ROS Control and Autophagy Regulation in Health and Disease

Reactive oxygen species (ROS) and autophagy are two highly complex and interrelated components of cell physiopathology, but our understanding of their integration and their contribution to cell homeostasis and disease is still limited. Sestrins (SESNs) belong to a family of highly conserved stress-inducible proteins that orchestrate antioxidant and autophagy-regulating functions protecting cells from various noxious stimuli, including DNA damage, oxidative stress, hypoxia, and metabolic stress. They are also relevant modulators of metabolism as positive regulators of the key energy sensor AMP-dependent protein kinase (AMPK) and inhibitors of mammalian target of rapamycin complex 1 (mTORC1). Since perturbations in these pathways are central to multiple disorders, SESNs might constitute potential novel therapeutic targets of broad interest. In this review, we discuss the current understanding of regulatory and effector networks of SESNs, highlighting their significance as potential biomarkers and therapeutic targets for different diseases, such as aging-related diseases, metabolic disorders, neurodegenerative diseases, and cancer.

Neuroprotective potency of some spice herbs, a literature review

In recent years, growing attention has been given to traditional medicine. In traditional medicine a large number of plants have been used to cure neurodegenerative diseases such as Alzheimer's disease (AD) and other memory related disorders. Crocus sativus (C. sativus), Nigella sativa (N. sativa), Coriandrum sativum (C. sativum), Ferula assafoetida (F. assafoetida), Thymus vulgaris (T. vulgaris), Zataria multiflora (Z. multiflora) and Curcuma longa (C. longa) were used traditionally for dietary, food additive, spice and various medicinal purposes. The Major components of these herbs are carotenoids, monoterpenes and poly phenol compounds which enhanced the neural functions. These medicinal plants increased anti-oxidant, decreased oxidant levels and inhibited acetylcholinesterase activity in the neural system. Furthermore, neuroprotective of plants occur via reduced pro-inflammatory cytokines such as IL-6, IL-1β, TNF-α and total nitrite generation. Therefore, the effects of the above mentioned medicinal and their active constituents improved neurodegenerative diseases which indicate their therapeutic potential in disorders associated with neuro-inflammation and neurotransmitter deficiency such as AD and depression.

Myricetin against ischemic cerebral injury in rat middle cerebral artery occlusion model

The purpose of the present study was to examine the effects of myricetin on reducing cerebral ischemia injury in a rat model. A rat model of permanent middle cerebral artery occlusion (pMCAO) was used in the present study. Rats were randomized into the following five groups: Sham, model, low‑myricetin (1 mg/kg), medium‑myricetin (5 mg/kg) and high‑myricetin (25 mg/kg) groups. Neurological deficit scores were evaluated by an examiner blinded to the experimental groups. Brain infarct size was estimated macroscopically using 2,3,5‑triphenyltetrazolium chloride staining. The levels of inflammatory factors tumor necrosis factor (TNF)‑α, interleukin (IL)‑6 and IL‑1β, and oxidative stress index superoxide dismutase (SOD), malondiadehyde (MDA), and the glutathione/glutathione disulfide (GSH/GSSG) ratio were measured by ELISA. The degree of brain cell apoptosis was determined using a terminal deoxynucleotidyl transferase dUTP nick‑end labeling assay. Protein expression levels of total or phosphorylated p38 mitogen activated protein kinase (MAPK), nuclear factor (NF)‑κB/p65 and protein kinase B (AKT) were determined using a western blotting assay. The neurological deficit score and infarct area induced by pMCAO decreased in a dose‑dependent manner following myricetin treatment. Furthermore, myricetin reduced the expression levels of IL‑1β, IL‑6, TNF‑α, and MDA, and increased GSH/GSSG ratio and SOD activity. A significant decrease in cell apoptosis was observed in response to myricetin. In addition, myricetin significantly increased the level of phosphorylated AKT protein, and decreased the phosphorylation of p38 MAPK and the level of NF‑κB/p65. Overall, the results of the present study suggested that myricetin exhibits a therapeutic effect by reducing ischemic cerebral injury, and the protective effect of myricetin may be associated with the p38 MAPK, NF‑κB/p65 and AKT signaling pathways.

Uncoupling Protein 2: A Key Player and a Potential Therapeutic Target in Vascular Diseases

Uncoupling protein 2 (UCP2) is an inner mitochondrial membrane protein that belongs to the uncoupling protein family and plays an important role in lowering mitochondrial membrane potential and dissipating metabolic energy with prevention of oxidative stress accumulation. In the present article, we will review the evidence that UCP2, as a consequence of its roles within the mitochondria, represents a critical player in the predisposition to vascular disease development in both animal models and in humans, particularly in relation to obesity, diabetes, and hypertension. The deletion of the UCP2 gene contributes to atherosclerosis lesion development in the knockout mice, also showing significantly shorter lifespan. The UCP2 gene downregulation is a key determinant of higher predisposition to renal and cerebrovascular damage in an animal model of spontaneous hypertension and stroke. In contrast, UCP2 overexpression improves both hyperglycemia- and high-salt diet-induced endothelial dysfunction and ameliorates hypertensive target organ damage in SHRSP. Moreover, drugs (fenofibrate and sitagliptin) and several vegetable compounds (extracts from Brassicaceae, berberine, curcumin, and capsaicin) are able to induce UCP2 expression level and to exert beneficial effects on the occurrence of vascular damage. As a consequence, UCP2 becomes an interesting therapeutic target for the treatment of common human vascular diseases.

Transient receptor potential channel 1/4 reduces subarachnoid hemorrhage-induced early brain injury in rats via calcineurin-mediated NMDAR and NFAT dephosphorylation

Transient receptor potential channel 1/4 (TRPC1/4) are considered to be related to subarachnoid hemorrhage (SAH)-induced cerebral vasospasm. In this study, a SAH rat model was employed to study the roles of TRPC1/4 in the early brain injury (EBI) after SAH. Primary cultured hippocampal neurons were exposed to oxyhemoglobin to mimic SAH in vitro. The protein levels of TRPC1/4 increased and peaked at 5 days after SAH in rats. Inhibition of TRPC1/4 by SKF96365 aggravated SAH-induced EBI, such as cortical cell death (by TUNEL staining) and degenerating (by FJB staining). In addition, TRPC1/4 overexpression could increase calcineurin activity, while increased calcineurin activity could promote the dephosphorylation of N-methyl-D-aspartate receptor (NMDAR). Calcineurin antagonist FK506 could weaken the neuroprotection and the dephosphorylation of NMDAR induced by TRPC1/4 overexpression. Contrarily, calcineurin agonist chlorogenic acid inhibited SAH-induced EBI, even when siRNA intervention of TRPC1/4 was performed. Moreover, calcineurin also could lead to the nuclear transfer of nuclear factor of activated T cells (NFAT), which is a transcription factor promoting the expressions of TRPC1/4. TRPC1/4 could inhibit SAH-induced EBI by supressing the phosphorylation of NMDAR via calcineurin. TRPC1/4-induced calcineurin activation also could promote the nuclear transfer of NFAT, suggesting a positive feedback regulation of TRPC1/4 expressions.

Sestrin2 Silencing Exacerbates Cerebral Ischemia/Reperfusion Injury by Decreasing Mitochondrial Biogenesis through the AMPK/PGC-1α Pathway in Rats

Sestrin2 (Sesn2) exerts neuroprotective properties in some neurodegenerative diseases. However, the role of Sesn2 in stroke is unclear. The AMP-activated protein kinase/peroxisome proliferator-activated receptor γ coactivator-1α (AMPK/PGC-1α) pathway plays an important role in regulating mitochondrial biogenesis, which helps prevent cerebral ischemia/reperfusion (I/R) injury. Here, we aimed to determine whether Sesn2 alleviated I/R damage by regulating mitochondrial biogenesis through the AMPK/PGC-1α signaling pathway. To be able to test this, Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 1 h with Sesn2 silencing. At 24 h after reperfusion, we found that neurological deficits were exacerbated, infarct volume was enlarged, and oxidative stress and neuronal damage were greater in the Sesn2 siRNA group than in the MCAO group. To explore protective mechanisms, an AMPK activator was used. Expression levels of Sesn2, p-AMPK, PGC-1α, NRF-1, TFAM, SOD2, and UCP2 were significantly increased following cerebral I/R. However, upregulation of these proteins was prevented by Sesn2 small interfering RNA (siRNA). In contrast, activation of AMPK with 5′-aminoimidazole-4-carboxamide riboside weakened the effects of Sesn2 siRNA. These results suggest that Sesn2 silencing may suppress mitochondrial biogenesis, reduce mitochondrial biological activity, and finally aggravate cerebral I/R injury through inhibiting the AMPK/PGC-1α pathway.

Astaxanthin has no effect on arterial stiffness, oxidative stress, or inflammation in renal transplant recipients: a randomized controlled trial (the XANTHIN trial)

BACKGROUND

There is evidence that renal transplant recipients have accelerated atherosclerosis that is manifest by increased cardiovascular morbidity and mortality. The high incidence of atherosclerosis is, in part, related to increased arterial stiffness, vascular dysfunction, elevated oxidative stress, and inflammation associated with immunosuppressive therapy. The carotenoid astaxanthin has shown potent antioxidant and anti-inflammatory properties.

OBJECTIVE

The aim was to investigate the effects of oral astaxanthin on arterial stiffness, oxidative stress, and inflammation in renal transplant recipients.

DESIGN

This trial used a randomized, placebo-controlled, double-blind design in which 61 patients received either 12 mg astaxanthin/d or an identical placebo orally for 1 y. Primary outcomes were 1) arterial stiffness measured by aortic pulse wave velocity (PWV), 2) oxidative stress assessed by total plasma F2-isoprostanes, and 3) inflammation assessed by plasma pentraxin-3. Secondary outcomes included vascular function, carotid artery intima-media thickness, augmentation index, central blood pressure, subendocardial viability ratio, and additional measures of oxidative stress and inflammation. Patients underwent assessments at baseline and at 6 and 12 mo.

RESULTS

Fifty-eight participants completed the study. There were no significant between-group differences in the changes in any of the primary outcome measures (PWV changed by +9.5% and +6.0%, F2-isoprostanes changed by -3.0% and -9.7%, and pentraxin-3 changed by +50.6% and -11.0% in the placebo and astaxanthin groups, respectively). There were no significant between-group differences in secondary outcome measures. Larger-than-expected variability decreased the power of the study and increased the possibility of a type 2 statistical error.

CONCLUSION

Astaxanthin (12 mg/d for 12 mo) had no effect on arterial stiffness, oxidative stress, or inflammation in renal transplant recipients. This trial was registered at the Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au/) as ACTRN12608000159358.

The role of 1,25-dyhydroxyvitamin D3 in mouse liver ischemia reperfusion injury: regulation of autophagy through activation of MEK/ERK signaling and PTEN/PI3K/Akt/mTORC1 signaling

Autophagy is an important mechanism for cellular homeostasis and survival during pathologic stress conditions in the liver, such as ischemia-reperfusion injury. In this study, we hypothesized a protective role of vitamin Din hepatic IR model. The administration of vitamin D displayed significantly preserved liver function as characterized by less histological damage and reduced serum enzymes level. We found that the protective effect was associated with ameliorated oxidative stress as manifested by the increase of antioxidant capacity and decrease of lipid peroxidation. Further, increased autophagic flux after vitamin D administration was demonstrated by the increase of protein light chain 3 (LC3) conversion both in vivo and in vitro. MEK/ERK and PTEN/PI3K/Akt/mTOR were both found critically involved in vitamin D-induced autophagy. By employing intracellular ROS and cell viability assay, we further confirmed this hypothesis with the observation that inhibition either of the MEK/ERK or PTEN/PI3K/Akt/mTOR pathway partly abolished the protective effect of vitamin D-induced autophagy, while inhibiting initiation of autophagy signaling pathway by knockdown of Beclin-1 completely reversed the protection provided by vitamin D. Collectively, the present results indicate that the protective role of vitamin D in murine hepatic IR injury is autophagy dependent, which is regulated by both MEK/ERK and PTEN/PI3K/Akt/mTOR pathway.

Interrelationship between angiogenesis, inflammation and oxidative stress in Indian patients with multiple myeloma

BACKGROUND

Multiple myeloma (MM) is a B-cell malignancy characterized by the accumulation of clonal population of plasma cells in the bone marrow (BM). A variety of angiogenic factors, proteases, reactive oxygen species and inflammatory cytokines induce the formation of an extensive and suitable BM microenvironment. Previous studies have established the importance of angiogenic factors, inflammatory molecules and oxidative stress in MM but their interplay and effect on each other are not being taken together.

METHODS

Circulatory levels of VEGF, angiopoietin-2 (Ang-2), IL-6 and TNF-α along with the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were investigated in 112 subjects including 62 MM patients and 50 healthy controls. Inter-stage analysis was done to evaluate the association of these molecules with the severity of disease. Pearson correlation was determined to find interrelationship, if any, between these molecules.

RESULTS

We have observed elevated levels of VEGF, Ang-2, IL-6, TNF-α and decreased activity of SOD, GPx in MM patients in comparison to controls. All these molecules also showed a trend with the severity of disease. We have found strong association between these factors upon their correlation and regression analysis.

CONCLUSION

This study is a step toward understanding the indepth contribution of angiogenesis, inflammation and oxidative stress together in making BM microenvironment suitable for growth, survival and proliferation of malignant plasma cells in MM.

Hydrogen Sulfide Ameliorates Early Brain Injury Following Subarachnoid Hemorrhage in Rats

Increasing studies have demonstrated the neuroprotective effect of hydrogen sulfide (H2S) in central nervous system (CNS) diseases. However, the potential application value of H2S in the therapy of subarachnoid hemorrhage (SAH) is still not well known. This study was to investigate the potential effect of H2S on early brain injury (EBI) induced by SAH and explore the underlying mechanisms. The role of sodium hydrosulfide (NaHS), a donor of H2S, in SAH-induced EBI, was investigated in both in vivo and in vitro. A prechiasmatic cistern single injection model was used to produce experimental SAH in vivo. In vitro, cultured primary rat cortical neurons and human umbilical vein endothelial cells (HUVECs) were exposed to OxyHb at concentration of 10 μM to mimic SAH. Endogenous production of H2S in the brain was significantly inhibited by SAH. The protein levels of the predominant H2S-generating enzymes in the brain, including cystathionineb-synthase (CBS) and 3-mercaptopyruvate sulfur transferase (3MST), were also correspondingly reduced by SAH, while treatment with NaHS restored H2S production and the expressions of CBS and 3MST. More importantly, NaHS treatment could significantly attenuate EBI (including brain edema, blood-brain barrier disruption, brain cell apoptosis, inflammatory response, and cerebral vasospasm) after SAH. In vitro, H2S protects neurons and endothelial function by functioning as an antioxidant and antiapoptotic mediator. Our results suggest that NaSH as an exogenous H2S donor could significantly reduce EBI induced by SAH.

Ischemic conditioning-induced endogenous brain protection: Applications pre-, per- or post-stroke

In the area of brain injury and neurodegenerative diseases, a plethora of experimental and clinical evidence strongly indicates the promise of therapeutically exploiting the endogenous adaptive system at various levels like triggers, mediators and the end-effectors to stimulate and mobilize intrinsic protective capacities against brain injuries. It is believed that ischemic pre-conditioning and post-conditioning are actually the strongest known interventions to stimulate the innate neuroprotective mechanism to prevent or reverse neurodegenerative diseases including stroke and traumatic brain injury. Recently, studies showed the effectiveness of ischemic per-conditioning in some organs. Therefore the term ischemic conditioning, including all interventions applied pre-, per- and post-ischemia, which spans therapeutic windows in 3 time periods, has recently been broadly accepted by scientific communities. In addition, it is extensively acknowledged that ischemia-mediated protection not only affects the neurons but also all the components of the neurovascular network (consisting of neurons, glial cells, vascular endothelial cells, pericytes, smooth muscle cells, and venule/veins). The concept of cerebroprotection has been widely used in place of neuroprotection. Intensive studies on the cellular signaling pathways involved in ischemic conditioning have improved the mechanistic understanding of tolerance to cerebral ischemia. This has added impetus to exploration for potential pharmacologic mimetics, which could possibly induce and maximize inherent protective capacities. However, most of these studies were performed in rodents, and the efficacy of these mimetics remains to be evaluated in human patients. Several classical signaling pathways involving apoptosis, inflammation, or oxidation have been elaborated in the past decades. Newly characterized mechanisms are emerging with the advances in biotechnology and conceptual renewal. In this review we are going to focus on those recently reported methodological and mechanistic discoveries in the realm of ischemic conditioning. Due to the varied time differences of ischemic conditioning in different animal models and clinical trials, it is important to define optimal timing to achieve the best conditioning induced neuroprotection. This brings not only an opportunity in the treatment of stroke, but challenges as well, as data is just becoming available and the procedures are not yet optimized. The purpose of this review is to shed light on exploiting these ischemic conditioning modalities to protect the cerebrovascular system against diverse injuries and neurodegenerative disorders.

Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes

Traumatic brain injury (TBI) is a significant clinical problem with few therapeutic interventions successfully translated to the clinic. Increased importance on the progressive, long-term consequences of TBI have been emphasized, both in the experimental and clinical literature. Thus, there is a need for a better understanding of the chronic consequences of TBI, with the ultimate goal of developing novel therapeutic interventions to treat the devastating consequences of brain injury. In models of mild, moderate, and severe TBI, histopathological and behavioral studies have emphasized the progressive nature of the initial traumatic insult and the involvement of multiple pathophysiological mechanisms, including sustained injury cascades leading to prolonged motor and cognitive deficits. Recently, the increased incidence in age-dependent neurodegenerative diseases in this patient population has also been emphasized. Pathomechanisms felt to be active in the acute and long-term consequences of TBI include excitotoxicity, apoptosis, inflammatory events, seizures, demyelination, white matter pathology, as well as decreased neurogenesis. The current article will review many of these pathophysiological mechanisms that may be important targets for limiting the chronic consequences of TBI.

Carotid artery blood flow decreases after rapid head rotation in piglets

Modification of cerebral perfusion pressure and cerebral blood flow (CBF) are crucial components of the therapies designed to reduce secondary damage after traumatic brain injury (TBI). Previously we documented a robust decrease in CBF after rapid sagittal head rotation in our well-validated animal model of diffuse TBI. Mechanisms responsible for this immediate (<10 min) and sustained (∼24 h) reduction in CBF have not been explored. Because the carotid arteries are a major source of CBF, we hypothesized that blood flow through the carotid arteries (Q) and vessel diameter (D) would decrease after rapid nonimpact head rotation without cervical spine injury. Four-week-old (toddler) female piglets underwent rapid (<20 msec) sagittal head rotation without impact, previously shown to produce diffuse TBI with reductions in CBF. Ultrasonographic images of the bilateral carotid arteries were recorded at baseline (pre-injury), as well as immediately after head rotation and 15, 30, 45, and 60 min after injury. Diameter (D) and waveform velocity (V) were used to calculate blood flow (Q) through the carotid arteries using the equation Q=(0.25)πD(2)V. D, V, and Q were normalized to the pre-injury baseline values to obtain a relative change after injury in right and left carotid arteries. Three-way analysis of variance and post-hoc Tukey-Kramer analyses were used to assess statistical significance of injury, time, and side. The relative change in carotid artery diameter and flow was significantly decreased in injured animals in comparison with uninjured sham controls (p<0.0001 and p=0.0093, respectively) and did not vary with side (p>0.39). The average carotid blood velocity did not differ between sham and injured animals (p=0.91). These data suggest that a reduction in global CBF after rapid sagittal head rotation may be partially mediated by a reduction in carotid artery flow, via vasoconstriction.

Targeting thioredoxin-1 with siRNA exacerbates oxidative stress injury after cerebral ischemia/reperfusion in rats

Reactive oxygen species and their detrimental effects on the brain after transient ischemia/reperfusion (I/R) have been implicated in the pathogenesis of ischemic reperfusion injury. Thioredoxin-1 (Trx-1) is an endogenous antioxidant protein that has neuroprotective effects. We hypothesized that Trx-1 plays a crucial role in regulating cerebral I/R injury. To be able to test this, 190 Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion (tMCAO) with Trx-1 siRNA (small interference RNA) injected 24 h prior to ischemia. At 24 h after tMCAO, we measured neurological deficits, infarct volume, and brain water content, and found that neurological dysfunction, brain infarct size, and brain edema were worse in the Trx-1 siRNA group than in the control group. Oxidative stress was evaluated by measuring superoxide dismutase activity and malondialdehyde level. The levels of Trx-1 and its cofactor, peroxiredoxin (Prdx), were significantly decreased after Trx-1 down-regulated. However, there is no significant difference in the Prdx mRNA level after administration of Trx-1 siRNA. In contrast, Prdx-SO3 protein levels were significantly increased in the Trx-1 siRNA group. We also investigated the specific role of nuclear factor erythroid 2-related factor 2 (Nrf2) in Trx-1 induction by knocking down Nrf2. Nrf2 siRNA injection decreased Trx-1 mRNA and protein expression. Our results suggest that the exacerbation of brain damage was associated with enhanced cerebral peroxidation in brain tissues. Moreover, these results revealed that Trx-1, which is more likely regulated by Nrf2, exerts a neuroprotective role probably through maintaining the reduction activity of Prdx1-4.