Improvement of Cognitive Deficit and Neuronal Damage in Rats with Chronic Cerebral Ischemia via Relative Long-term Inhibition of Rho-kinase

Hydroxyfasudil regulates immune balance and suppresses inflammatory responses in the treatment of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a central nervous system (CNS) disease with complicated etiology. Multifocal demyelination and invasion of inflammatory cells are its primary pathological features. Fasudil has been confirmed to improve experimental autoimmune encephalomyelitis (EAE), an animal model of MS. However, Fasudil is accompanied by several shortcomings in the clinical practice. Hydroxyfasudil is a metabolite of Fasudil in the body with better pharmaceutical properties. Therefore, we attempted to study the influence of Hydroxyfasudil upon EAE mice. The results demonstrated that Hydroxyfasudil relieved the symptoms of EAE and the associated pathological damage, reduced the adhesion molecules and chemokines, decreased the invasion of peripheral immune cells. Simultaneously, Hydroxyfasudil modified the rebalance of peripheral T cells. Moreover, Hydroxyfasudil shifted the M1 phenotype to M2 polarization, inhibited inflammatory signaling cascades as well as inflammatory factors, and promoted anti-inflammatory factors in the CNS. In the end, mice in the Hydroxyfasudil group expressed more tight junction proteins, indirectly indicating that the blood-brain barrier (BBB) was protected. Our results indicate that Hydroxyfasudil may be a prospective treatment for MS.

Strategies for Treatment of Disease-Associated Dementia Beyond Alzheimer's Disease: An Update

Memory, cognition, dementia, and neurodegeneration are complexly interlinked processes with various mechanistic pathways, leading to a range of clinical outcomes. They are strongly associated with pathological conditions like Alzheimer's disease, Parkinson's disease, schizophrenia, and stroke and are a growing concern for their timely diagnosis and management. Several cognitionenhancing interventions for management include non-pharmacological interventions like diet, exercise, and physical activity, while pharmacological interventions include medicinal agents, herbal agents, and nutritional supplements. This review critically analyzed and discussed the currently available agents under different drug development phases designed to target the molecular targets, including cholinergic receptor, glutamatergic system, GABAergic targets, glycine site, serotonergic targets, histamine receptors, etc. Understanding memory formation and pathways involved therein aids in opening the new gateways to treating cognitive disorders. However, clinical studies suggest that there is still a dearth of knowledge about the pathological mechanism involved in neurological conditions, making the dropouts of agents from the initial phases of the clinical trial. Hence, a better understanding of the disease biology, mode of drug action, and interlinked mechanistic pathways at a molecular level is required.

Effects of Ceftriaxone on Oxidative Stress and Inflammation in a Rat Model of Chronic Cerebral Hypoperfusion

Ceftriaxone (CTX) exerts a neuroprotective effect by decreasing glutamate excitotoxicity. We further studied the underlying mechanisms and effects of CTX early post-treatment on behavior in a cerebral hypoperfusion rats. The rats’ common carotid arteries (2VO) were permanently ligated. CTX was treated after ischemia. Biochemical studies were performed to assess antioxidative stress and inflammation. Behavioral and histological studies were then tested on the ninth week after vessel ligation. The 2VO rats showed learning and memory deficits as well as working memory impairments without any motor weakness. The treatment with CTX was found to attenuate white matter damage, MDA production, and interleukin 1 beta and tumor necrosis factor alpha production, mainly in the hippocampal area. Moreover, CTX treatment could increase the expression of glia and the glial glutamate transporters, and the neuronal glutamate transporter. Taken together, our data indicate the neuroprotective mechanisms of CTX involving the upregulation of glutamate transporters’ expression. This increased expression contributes to a reduction in glutamate excitotoxicity and oxidative stress as well as pro-inflammatory cytokine production, thus resulting in the protection of neurons and tissue from further damage. The present study highlights the mechanism of the effect of CTX treatment and of the underlying ischemia-induced neuronal damage.

ROCK and PDE-5 Inhibitors for the Treatment of Dementia: Literature Review and Meta-Analysis

Dementia is a disease in which memory, thought, and behavior-related disorders progress gradually due to brain damage caused by injury or disease. It is mainly caused by Alzheimer’s disease or vascular dementia and several other risk factors, including genetic factors. It is difficult to treat as its incidence continues to increase worldwide. Many studies have been performed concerning the treatment of this condition. Rho-associated kinase (ROCK) and phosphodiesterase-5 (PDE-5) are attracting attention as pharmacological treatments to improve the symptoms. This review discusses how ROCK and PDE-5 affect Alzheimer’s disease, vascular restructuring, and exacerbation of neuroinflammation, and how their inhibition helps improve cognitive function. In addition, the results of the animal behavior analysis experiments utilizing the Morris water maze were compared through meta-analysis to analyze the effects of ROCK inhibitors and PDE-5 inhibitors on cognitive function. According to the selection criteria, 997 publications on ROCK and 1772 publications on PDE-5 were screened, and conclusions were drawn through meta-analysis. Both inhibitors showed good improvement in cognitive function tests, and what is expected of the synergy effect of the two drugs was confirmed in this review.

Inflammation and Rho-Associated Protein Kinase-Induced Brain Changes in Vascular Dementia

Patients with vascular dementia, caused by cerebral ischemia, experience long-term cognitive impairment due to the lack of effective treatment. The mechanisms of and treatments for vascular dementia have been investigated in various animal models; however, the insufficient information on gene expression changes that define pathological conditions hampers progress. To investigate the underlying mechanism of and facilitate treatment development for vascular dementia, we established a mouse model of chronic cerebral hypoperfusion, including bilateral carotid artery stenosis, by using microcoils, and elucidated the molecular pathway underlying vascular dementia development. Rho-associated protein kinase (ROCK) 1/2, which regulates cellular structure, and inflammatory cytokines (IL-1 and IL-6) were upregulated in the vascular dementia model. However, expression of claudin-5, which maintains the blood–brain barrier, and MAP2 as a nerve cell-specific factor, was decreased in the hippocampal region of the vascular dementia model. Thus, we revealed that ROCK pathway activation loosens the tight junction of the blood–brain barrier and increases the influx of inflammatory cytokines into the hippocampal region, leading to neuronal death and causing cognitive and emotional dysfunction. Our vascular dementia model allows effective study of the vascular dementia mechanism. Moreover, the ROCK pathway may be a target for vascular dementia treatment development in the future.

Pyomelanin produced by Streptomyces sp. ZL-24 and its protective effects against SH-SY5Y cells injury induced by hydrogen peroxide

A soluble melanin pigment produced by Streptomyces sp. ZL-24 was purified and named StrSM. The elemental analysis of StrSM showed it consists of carbon, hydrogen, and oxygen. The spectrum analysis, including ultraviolet-visible absorption spectrum, Fourier-transform infrared spectrum, and pyrolysis-gas chromatography-mass spectrometry, indicated that StrSM might be pyomelanin. High performance liquid chromatography and liquid chromatography-mass spectra analysis of intermediate metabolite showed the presence of homogentisic acid (HGA). Moreover, the enzyme 4-hydroxyphenylpyruvate dioxygenase, involved in HGA biosynthesis, showed high activity during melanin production. Subsequently, a tyrosinase gene (melC2) and hydroxyphenylpyruvate dioxygenase gene double mutant demonstrated StrSM is pyomelanin. In vitro bioactivity assay showed that StrSM had excellent protective capability against SH-SY5Y cell oxidative injury. To our knowledge, the results firstly provide comprehensive data on Streptomyces pyomelanin identification and a promising candidate compound to treat oxidative injury of neurocytes.

Environmental enrichment combined with fasudil promotes motor function recovery and axonal regeneration after stroke

Fasudil, a Rho-associated protein kinase (ROCK) inhibitor, has a protective effect on the central nervous system. In addition, environmental enrichment is a promising technique for inducing the recovery of motor impairments in ischemic stroke models. The present study aimed to explore whether environmental enrichment combined with fasudil can facilitate motor function recovery and induce cortical axonal regeneration after stroke. First, a mouse model of ischemic cerebral stroke was established by photochemical embolization of the left sensorimotor cortex. Fasudil solution (10 mg/kg per day) was injected intraperitoneally for 21 days after the photothrombotic stroke. An environmental enrichment intervention was performed on days 7–21 after the photothrombotic stroke. The results revealed that environmental enrichment combined with fasudil improved motor function, increased growth-associated protein 43 expression in the infarcted cerebral cortex, promoted axonal regeneration on the contralateral side, and downregulated ROCK, p-LIM domain kinase (LIMK)1, and p-cofilin expression. The combined intervention was superior to monotherapy. These findings suggest that environmental enrichment combined with fasudil treatment promotes motor recovery after stroke, at least partly by stimulating axonal regeneration. The underlying mechanism might involve ROCK/LIMK1/cofilin pathway regulation. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 20160858A232) on February 24, 2016.

A Rho-kinase inhibitor reverses learning and memory deficits in a Rat model of chronic cerebral ischemia by altering Bcl-2/Bax-NMDAR signaling in the cerebral cortex

The current study investigated whether a Rho-kinase inhibitor alleviated impairments in a rat model of chronic cerebral ischemia and examined the specific pathological mechanisms by which Rho-kinase impacts neuronal damage and cognitive dysfunction. Adult Sprague-Dawley rats underwent permanent bilateral carotid artery occlusion (BCAO) to establish our chronic cerebral ischemia model. Chronic Y27632 administration reversed the abnormal behaviors of BCAO-treated rats in the Morris water maze. We performed Western blot analyses of the apoptosis-related proteins Bcl-2 and Bax to examine the potential mechanism underlying the beneficial effects of Y27632 on cerebral ischemia and showed for the first time that Y27632 reversed the decrease in the Bcl-2/Bax ratio in BCAO model rats. Y27632 restored the depression of NR2A- and NR2B-containing N-methyl-d-aspartate receptors (NMDARs) in the cerebral cortex of BCAO model rats. We also investigated these effects on middle cerebral artery occlusion (MCAO) model rats and observed some differences between the two models. In summary, our data provide evidence supporting the hypothesis that Rho-kinase inhibitors exert neuroprotective effects on cerebral ischemia. The Bcl-2/Bax-NMDAR signaling pathway in the cerebral cortex may be responsible for the protective effects of the Rho-kinase inhibitor, and this pathway may represent a pharmacological target for curative clinical strategies.

Acupuncture Rescues Cognitive Impairment and Upregulates Dopamine-β-Hydroxylase Expression in Chronic Cerebral Hypoperfusion Rats

Alteration of dopamine (DA) and noradrenaline (NA) contributes to cognitive function. Acupuncture has been shown to affect DA and NA in chronic cerebral hypoperfusion (CCH) rats. However, the effect of acupuncture on DA-β-hydroxylase (DBH), the biosynthetic enzyme of NA, remains unknown. In CCH rats we established chronic hypoperfusion by bilateral common carotid artery occlusion (two-vessel occlusion, 2VO) and treated them with acupuncture. Acupuncture displayed beneficial effects on hippocampus-dependent memory impairments, including nonspatial and spatial memory. That is also reflected in hippocampus long-term-potentiation (LTP). Moreover, DBH expression in the hippocampus and DBH activity in cerebrospinal fluid were upregulated after acupuncture treatment. In conclusion, these in vivo findings suggest that acupuncture exerts a therapeutic effect on hippocampus-dependent memory and hippocampus LTP in CCH rats, which may be partially related to the modulation of DBH in the hippocampus.

Neurorestorative effects of epigallocatechin-3-Gallate on cognitive function in a chronic cerebral hypoperfusion rat model

PURPOSE

This study investigated whether (-)-epigallocatechin-3-gallate (EGCG) can enhance cognition by a neurorestorative effect in a rat model of bilateral common carotid artery occlusion (BCCAO).

METHODS

Forty-eight male, 8-week-old Sprague-Dawley rats were randomly allocated to four groups 6 weeks after BCCAO or sham operation: EGCG-single intravenous injection (25 mg/kg/day; SIV group), EGCG-multiple intraperitoneal injection (50 mg/kg/day for 5 days; MIP group), untreated BCCAO group (untreated group), and sham-operated group (sham group).

RESULTS

Escape latency was significantly shorter in the SIV and MIP groups than in the untreated group. SIV and MIP groups were significantly different from the untreated group in the activity of superoxide dismutase and the content of malondialdehyde (p < 0.05). Protein expression level of brain-derived neurotrophic factor was not significantly different between groups (p > 0.05), while protein expression of vascular endothelial growth factor was significantly lower in the SIV group than in the untreated group (p < 0.05). Protein expression of N-methyl-D-aspartate receptor subunits NR1 and NR2B was significantly higher in the MIP group than in the untreated group (p < 0.05).

CONCLUSIONS

EGCG administration at 6 weeks after BCCAO is neurorestorative via an anti-oxidant effect and synaptogenesis, except for angiogenesis.

Clonidine preconditioning improved cerebral ischemia-induced learning and memory deficits in rats via ERK1/2-CREB/ NF-κB-NR2B pathway

Clonidine, a classical α-2 adrenergic agonists, has been shown to antagonize brain damage caused by hypoxia, cerebral ischemia and excitotoxicity and reduce cerebral infarction volume in recent studies. We herein investigate the regulatory effect and possible underlying mechanism of clonidine on learning and memory in rats with cerebral ischemia. The cerebral ischemia rat model was established by right middle cerebral artery occlusion for 2h and reperfusion for 28 days. Drugs were administrated to the rats for consecutive 7 days intraperitoneally and once again on the day of surgery. The learning and memory in rats was assayed by Morris water maze. Moreover, protein expression levels of NMDAR2B (NR2B)/ phosphor - NR2B, ERK1/2/phosphor- ERK1/2, CREB/phosphor-CREB and NF-κB/phosphor-NF-κB in the cortex and hippocampus of the rats were assayed by western blotting. Our results demonstrated that clonidine treatment significantly abrogated the negative effect induced by cerebral ischemia on the learning and memory in the rats. In the Western blotting assay, clonidine treatment led to significant up-regulation of the expression level of NR2B and Phospho-NR2B in the hippocampus of the rats when compared with the cerebral ischemia group. Furthermore, clonidine also significantly decreased the protein expression levels of ERK1/2, Phospho-ERK1/2, CREB, Phospho-CREB and Phospho-NF-κB in the hippocampus of the rats when compared with the cerebral ischemia group. In conclusion, clonidine could improve the learning and memory ability of rats with cerebral ischemia, and NR2B, ERK1/2, CREB, NF-κB were involved in this effect.

Arginine vasopressin ameliorates spatial learning impairments in chronic cerebral hypoperfusion via V1a receptor and autophagy signaling partially

Chronic cerebral hypoperfusion (CCH) is a major factor contributing to neurological disorders and cognitive decline. Autophagy activation is believed to provide both beneficial and detrimental roles during hypoxic/ischemic cellular injury. Although arginine vasopressin (AVP) has been strongly involved in many behaviors, especially in learning and memory, the effects of AVP on CCH and their molecular mechanisms remain unclear. Here, to investigate whether there was neuroprotective effects of AVP on CCH through V1a receptor (an AVP receptor) signaling, permanent bilateral carotid arteries occlusion (two vessel occlusion, 2VO) was used to establish a rat model of CCH, and hypertonic saline (5.3%) was injected intraperitoneally to induce the secretion of AVP. Results showed that hypertonic saline effectively alleviated spatial learning and memory deficit, enhanced synaptic plasticity of CA3-CA1 hippocampal synapses, upregulated N-methyl-d-aspartate receptor subunit 2B (NR2B) and postsynaptic density protein 95 (PSD-95) surface expressions, reduced oxidative stress and increased Nissl bodies in 2VO model rats. These phenomena were significantly decreased by V1a receptor antagonist SR49059. Interestingly, hypertonic saline also upregulated autophagy in the hippocampus of 2VO rats partly through V1a receptor. These findings imply that AVP has a beneficial role for the treatment of cognitive impairments partly through V1a receptor signaling in CCH, which is possibly related to improving synaptic plasticity by promoting NR2B and PSD-95 externalization and by enhancing autophagy.

Hypoxia Inducible Factor 1α Promotes Endogenous Adaptive Response in Rat Model of Chronic Cerebral Hypoperfusion

Hypoxia inducible factor 1α (HIF-1α), a pivotal regulator of gene expression in response to hypoxia and ischemia, is now considered to regulate both pro-survival and pro-death responses depending on the duration and severity of the stress. We previously showed that chronic global cerebral hypoperfusion (CCH) triggered long-lasting accumulation of HIF-1α protein in the hippocampus of rats. However, the role of the stabilized HIF-1α in CCH is obscure. Here, we knock down endogenous HIF-1α to determine whether and how HIF-1α affects the disease processes and phenotypes of CCH. Lentivirus expressing HIF-1α small hairpin RNA was injected into the bilateral hippocampus and bilateral ventricles to knock down HIF-1α gene expression in the hippocampus and other brain areas. Permanent bilateral common carotid artery occlusions, known as 2-vessel occlusions (2VOs), were used to induce CCH in rats. Angiogenesis, oxidative stress, histopathological changes of the brain, and cognitive function were tested. Knockdown of HIF-1α prior to 2VO significantly exacerbates the impairment of learning and memory after four weeks of CCH. Mechanically, reduced cerebral angiogenesis, increased oxidative damage, and increased density of astrocytes and microglia in the cortex and some subregions of hippocampus are also shown after four weeks of CCH. Furthermore, HIF-1α knockdown also disrupts upregulation of regulated downstream genes. Our findings suggest that HIF-1α-protects the brain from oxidative stress and inflammation response in the disease process of CCH. Accumulated HIF-1α during CCH mediates endogenous adaptive processes to defend against more severe hypoperfusion injury of the brain, which may provide a therapeutic benefit.

Modulating Astrocyte Transition after Stroke to Promote Brain Rescue and Functional Recovery: Emerging Targets Include Rho Kinase

Stroke is a common and serious condition, with few therapies. Whilst previous focus has been directed towards biochemical events within neurons, none have successfully prevented the progression of injury that occurs in the acute phase. New targeted treatments that promote recovery after stroke might be a better strategy and are desperately needed for the majority of stroke survivors. Cells comprising the neurovascular unit, including blood vessels and astrocytes, present an alternative target for supporting brain rescue and recovery in the late phase of stroke, since alteration in the unit also occurs in regions outside of the lesion. One of the major changes in the unit involves extensive morphological transition of astrocytes resulting in altered energy metabolism, decreased glutamate reuptake and recycling, and retraction of astrocyte end feed from both blood vessels and neurons. Whilst globally inhibiting transitional change in astrocytes after stroke is reported to result in further damage and functional loss, we discuss the available evidence to suggest that the transitional activation of astrocytes after stroke can be modulated for improved outcomes. In particular, we review the role of Rho-kinase (ROCK) in reactive gliosis and show that inhibiting ROCK after stroke results in reduced scar formation and improved functional recovery.

Triple negative breast cancer: a multi-omics network discovery strategy for candidate targets and driving pathways

Triple negative breast cancer (TNBC) represents approximately 15% of breast cancers and is characterized by lack of expression of both estrogen receptor (ER) and progesterone receptor (PR), together with absence of human epidermal growth factor 2 (HER2). TNBC has attracted considerable attention due to its aggressiveness such as large tumor size, high proliferation rate, and metastasis. The absence of clinically efficient molecular targets is of great concern in treatment of patients with TNBC. In light of the complexity of TNBC, we applied a systematic and integrative transcriptomics and interactomics approach utilizing transcriptional regulatory and protein-protein interaction networks to discover putative transcriptional control mechanisms of TNBC. To this end, we identified TNBC-driven molecular pathways such as the Janus kinase-signal transducers, and activators of transcription (JAK-STAT) and tumor necrosis factor (TNF) signaling pathways. The multi-omics molecular target and biomarker discovery approach presented here can offer ways forward on novel diagnostics and potentially help to design personalized therapeutics for TNBC in the future.

Gallic acid improves cognitive, hippocampal long-term potentiation deficits and brain damage induced by chronic cerebral hypoperfusion in rats

Abstract: Cerebral Hypoperfusion Ischemia (CHI) has important role in neuronal damage and behavioral deficits, including memory and Long-term Potentiation (LTP) impairment. Protective effects of Gallic Acid (GA) on memory, hippocampus LTP and cell viability were examined in permanent bilateral common carotid artery occlusion in rats. Animals were divided into 9 groups: Control (Cont); sham operated (Sho); Cerebral Hypoperfusion Ischemia (CHI); CHI received normal saline (CHI +Veh); CHI treated with different doses gallic acid (50, 100, 200 mg kg(-1) for 5 days before and 5 days after CHI induction, orally); CHI treated with phenytoin (50 mg kg(-1), ip) (CHI+Phe); and sham operated received 100 mg kg(-1), orally (Sho+GA100). CHI was induced by bilateral common carotid artery occlusion (2VO). Behavioral, electrophysiological and histological evaluations were performed. Data were analyzed by one-way and repeated measures ANOVA followed by tukey's post-hoc test. GA improved passive avoidance memory, hippocampal LTP and cell. viability in hippocampus and cortex of ischemic rats significantly (p < 0.01). The results suggest that gallic acid via its antioxidative and free radicals scavenging properties attenuates CHI induced behavioral and electrophysiological deficits and has significant protective effect on brain cell viability. Dose of 100 mg kg(-1) GA has affected the ischemic but not intact rats and its effect was more potent significantly than phenytoin, a routine drug for ischemic subjects.

Hydroxyl fasudil, an inhibitor of Rho signaling, improves erectile function in diabetic rats: a role for neuronal ROCK

INTRODUCTION

The pathogenesis of diabetic erectile dysfunction (ED) includes neuropathy, but the molecular basis for neurogenic ED is incompletely understood. The RhoA/ROCK pathway has been implicated in diabetic neuropathy and in ED, but its role in diabetic neurogenic ED is not known.

AIMS

The aim of this study was to determine whether hydroxyl fasudil, a ROCK inhibitor, affects diabetic neuropathy-related ED.

METHODS

Type 1 diabetes mellitus was induced in male rats by streptozotocin (75 mg/kg, intraperitoneally). After 8 weeks, diabetic rats were administered hydroxyl fasudil, a selective ROCK inhibitor (10 mg/kg/day, intraperitoneally) or vehicle, for 4 weeks. Age-matched control, nondiabetic, rats were treated intraperitoneally for 4 weeks with saline. At week 12, after a 2 day washout, neuro-stimulated erectile function was evaluated. Major pelvic ganglia (MPG) were collected for Western blot analysis of RhoA, ROCK-1, ROCK-2, phospho (P)-AKT (Ser(473) ), and P-phosphatase and tensin homolog (P-PTEN) (Ser(380) /Thr(382/383) ).

MAIN OUTCOME MEASURES

Effect of ROCK inhibitor hydroxyl fasudil on erectile function and ROCK/P-AKT/P-PTEN pathway in the MPG of diabetic rats.

RESULTS

Erectile response was significantly (P < 0.05) reduced in diabetic rats compared with nondiabetic rats and was preserved (P < 0.05) in diabetic rats treated with hydroxyl fasudil. In diabetic rats, RhoA and ROCK-2 protein expressions in MPG were increased (P < 0.05) and remained increased in hydroxyl fasudil-treated rats. P-AKT (Ser(473) ) expression was decreased (P < 0.05), whereas P-PTEN (Ser(380) /Thr(382/383) ) expression was increased (P < 0.05) in MPG of diabetic rats compared with nondiabetic rats, and both were reversed (P < 0.05) in diabetic rats treated with hydroxyl fasudil.

CONCLUSION

Improved erectile function and restored P-AKT and P-PTEN in the MPG with hydroxyl fasudil treatment suggest the role of Rho signaling via PTEN/AKT pathway in neurogenic diabetic ED.

Surgical incision-induced nociception causes cognitive impairment and reduction in synaptic NMDA receptor 2B in mice

Postoperative cognitive dysfunction (POCD) is associated with impairments in daily functioning, and increased morbidity and mortality. However, the causes and neuropathogenesis of POCD remain largely unknown. Uncontrolled pain often occurs postoperatively. We therefore set out to determine the effects of surgical incision-induced nociception on the cognitive function and its underlying mechanisms in 3- and 9-month-old mice. The mice had surgical incision in the hindpaw and then were tested for nociceptive threshold, learning, and memory. Brain levels of NMDA receptor and cyclin-dependent kinase 5 (CDK5) were also assessed. We found that surgical incision-induced nociception in mice led to a decreased freezing time in the tone test (which assesses the hippocampus-independent learning and memory function), but not the context test, of Fear Conditioning System at 3 and 7 d, but not 30 d post incision in 9-month-old, but not 3-month-old mice. Consistently, the surgical incision selectively decreased synaptic NMDA receptor 2B levels in the medial prefrontal cortex, and increased levels of tumor necrosis factor-α and CDK5 in the cortex, but not hippocampus, of the mice. Finally, eutectic mixture of local anesthetics and CDK5 inhibitor, roscovitine, attenuated the surgical incision-induced reduction in the synaptic NMDA receptor 2B levels and learning impairment. These results suggested that surgical incision-induced nociception reduced the synaptic NMDA receptor 2B level in the medial prefrontal cortex of mice, which might lead to hippocampus-independent learning impairment, contributing to POCD. These findings call for further investigation to determine the role of surgical incision-induced nociception in POCD.

PI3K/Akt signal pathway involved in the cognitive impairment caused by chronic cerebral hypoperfusion in rats

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological state that usually occurs in conditions such as vascular dementia and Alzheimer's disease, both of which are characterized by cognitive impairment. In previous studies we found that learning capacity and memory were gradually impaired with CCH, which altered the expression of synaptophysin, microtubule associated protein-2, growth associated protein-43, brain-derived neurotrophic factor, nerve growth factor, N-methyl-D-aspartate receptor subunit 1, cAMP response element-binding protein and tau hyperphosphorylation in the hippocampus. However, the molecular basis of cognitive impairment in CCH remains obscure. Here we explore the hypothesis that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signal pathway is involved in this type of cognitive impairment. In order to determine if the expression of PI3K, Akt and phosphorylated Akt (p-Akt) proteins are altered at different stages of CCH with differing levels of cognitive impairment. we performed permanent, bilateral occlusion of the common carotid arteries (2-VO) to induce CCH. Adult male SD rats were randomly divided into sham-operated group, 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group. Behavior tests were utilized to assess cognitive abilities, while western blots were utilized to evaluate protein expression. Rats in the 2-VO groups spent less time exploring novel objects than those in the sham-operated group, and the discrimination ratio of the 2-VO 8 weeks group and the sham-operated group were higher than chance (0.50). Escape latencies in the Morris water maze task in the 2-VO 1 week group were longer than those in the sham-operated group on day 4 and day 5, while escape latencies in the 2-VO 4 weeks group were longer than those in the sham-operated group from day 3 to day 5. Escape latencies in 2-VO 8 weeks group were longer than those in the sham-operated group from day 2 to day 5. NE (northeast) square swimming times in the 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group were shorter than that in the sham-operated group. Western blotting showed that the PI3K expression in the 2-VO 1 week group was lower than that in sham-operated group, while p-Akt expression in the 2-VO 8 weeks group was higher than that in the sham-operated group. There was a linear relationship between the PI3K expression and the discrimination ratio, as well as a linear relationship between the PI3K and NE square swimming time. Thus, we propose that the PI3K/Akt signal pathway is an important cell pathway that is associated with the cognitive impairment following CCH.

Neuronal damage, central cholinergic dysfunction and oxidative damage correlate with cognitive deficits in rats with chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion has been identified to be a risk factor for cognitive decline in aging, vascular dementia, and Alzheimer's disease. Substantial evidence has shown that chronic cerebral hypoperfusion may cause cognitive impairment, but the underlying neurobiological mechanism is poorly understood so far. In this study, we used a rat model of chronic cerebral hypoperfusion by permanent bilateral common carotid artery occlusion (BCCAO) to investigate the alterations of neuronal damage, glial activation oxidative stress and central cholinergic dysfunction, and their causal relationship with the cognitive deficits induced by chronic cerebral hypoperfusion. We found that BCCAO rats exhibited spatial learning and memory impairments and working memory dysfunction 12 weeks after BCCAO compared with sham-operated rats, simultaneously accompanied by significantly increased neuronal damage and glial cell activation in the cerebral cortex and hippocampus. Twelve weeks of BCCAO treatment in rats resulted in central cholinergic dysfunction and increased oxidative damage compared with sham-operated rats. Correlational analyses revealed that spatial learning and memory impairments and working memory dysfunction were significantly correlated with the measures of neuronal damage, central cholinergic dysfunction and oxidative damage in the cerebral cortex and hippocampus of rats with BCCAO. Moreover, the measures of neuronal damage and central cholinergic dysfunction were significantly correlated with the indexes of oxidative damage in rats with BCCAO. Collectively, this study provides novel evidence that neuronal damage and central cholinergic dysfunction is likely due to increased oxidative stress under the condition of chronic cerebral hypoperfusion. Furthermore, the results of the present study suggest that neuronal damage, central cholinergic dysfunction and oxidative damage in the brain following the reduction of cerebral blood flow could be involved in cognitive deficits induced by chronic cerebral hypoperfusion.

Change of Nrf2 expression in rat hippocampus in a model of chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) is common in vascular dementia and Alzheimer's disease. CCH-related oxidative damage plays a significant role in the development of cognitive impairment. Nuclear factor-erythroid 2-related factor-2 (Nrf2) mediates activation of the antioxidant responsive element (ARE)-related gene expression, which is crucial to the endogenous antioxidative system. In this case, we used permanent bilateral occlusion of common carotid arteries (2VO) to mimic CCH. The expression of Nrf2 in different regions of the hippocampus as well as the ability of nuclear Nrf2 and ARE binding have been examined. A phenomenon has been observed that the DNA binding activities were down-regulated. Interestingly, the expression of Nrf2 rose significantly in most regions of rat hippocampus within three weeks after the 2VO surgery. The mismatch might attribute to Nrf2 dysfunction and compensatory synthesis. A conclusion can be drawn that Nrf2 dysfunction is an important factor as a cause of CCH-induced oxidative damage and Nrf2 can be treated as a promising target to alleviate oxidative damage, even cognitive impairment caused by CCH.

Clitoria ternatea ameliorated the intracerebroventricularly injected streptozotocin induced cognitive impairment in rats: behavioral and biochemical evidence

RATIONALE

Clitoria ternatea, commonly known as Aparajita, is used as Medhya rasayana in Ayurveda. The role of C. ternatea in experimental models of cognitive impairment is yet to be explored.

OBJECTIVES

The present study was designed to study the effect of aqueous and hydroalcoholic extracts of C. ternatea on biochemical and behavioral parameters related to cognitive impairment in in vitro and in vivo studies.

METHODS

In vitro free radical scavenging and enzyme-inhibitory (cholinesterase, glycogen synthase kinase-3-β, rho kinase, prolyl endopeptidase, catechol-O-methyl transferase, and lipoxygenase) activities of aqueous and hydroalcoholic extracts of C. ternatea plant were evaluated. Based on in vitro results, hydroalcoholic extract of C. ternatea (100, 300, and 500 mg/kg, p.o.) was selected for evaluation in intracerebroventricularly injected streptozotocin (STZ)-induced cognitive impairment in male Wistar rats. Behavioral assessment was performed at baseline and on the 14th, 21st, and 28th days after STZ injection using elevated plus maze, passive avoidance, Morris water maze, and photoactometer. Oxidative stress parameters (malondialdehyde, reduced glutathione, nitric oxide levels, and superoxide dismutase activity), cholinesterase activity, and rho kinase (ROCK II) expression were studied in cerebral cortex and hippocampus of rats' brain at the end of the study.

RESULTS

The hydroalcoholic extract possessed significantly more in vitro antioxidant and enzyme-inhibitory activities as compared to aqueous extract. The hydroalcoholic extract of C. ternatea prevented STZ-induced cognitive impairment dose dependently by reducing oxidative stress, cholinesterase activity, and ROCK II expression.

CONCLUSION

In vitro and in vivo results suggest the potential of hydroalcoholic extract of C. ternatea for treatment of cognitive deficit in neurological disorders.

Developmentally divergent effects of Rho-kinase inhibition on cocaine- and BDNF-induced behavioral plasticity

Prefrontal cortical dendritic spine remodeling during adolescence may open a window of vulnerability to pathological stimuli that impact long-term behavioral outcomes, but causal mechanisms remain unclear. We administered the Rho-kinase inhibitor HA-1077 during three adolescent periods in mice to destabilize dendritic spines. In adulthood, cocaine-induced locomotor activity was exaggerated. By contrast, when administered in adulthood, HA-1077 had no psychomotor consequences and normalized food-reinforced instrumental responding after orbitofrontal-selective knockdown of Brain-derived neurotrophic factor, a potential factor in addiction. Thus, early-life Rho-kinase inhibition confers cocaine vulnerability, but may actually protect against pathological reward-seeking - particularly in cases of diminished neurotrophic support - in adulthood.

Amelioration of intracerebroventricular streptozotocin induced cognitive impairment by Evolvulus alsinoides in rats: in vitro and in vivo evidence

Evolvulus alsinoides, also known as Shankpushapi, is a commonly used traditional medicine for enhancing memory. We evaluated the in vitro free radical scavenging and enzymes [acetylcholinesterase, butyrylcholinestrase, glycogen synthase kinase-3-β (GSK-3-β), rho kinase (ROCK II), prolyl endopeptidase (PEP), catechol-O-methyl transferase (COMT) and lipoxygenase (LOX)] inhibitory activities of aqueous and hydro-alcoholic extracts of E. alsinoides. Hydro-alcoholic extract of E. alsinoides demonstrated more free radical scavenging activity as compared to aqueous extract. Hydro-alcoholic extract also showed higher cholinesterase, GSK-3-β, ROCK II, PEP, COMT and LOX enzyme inhibitory activities as compared to aqueous extract. Phytochemical analysis revealed more flavanoids in hydro-alcoholic extract as compared to aqueous extract but no significant difference in phenolic content of the two extracts was observed. Based on in vitro data, hydro-alcoholic extract (100, 300 and 500mg/kg, p.o.) was selected for in vivo study in intracerebroventricularly injected streptozotocin (STZ) induced cognitive impairment in male Wistar rats. Elevated plus maze, passive avoidance and Morris water maze were used for assessment of cognitive function on 14th, 21st and 28th day after STZ injection. Oxidative stress parameters (malondialdehyde, reduced glutathione, nitric oxide levels and superoxide dismutase activity), cholinergic dysfunction and rho kinase (ROCK II) expression were studied in cerebral cortex and hippocampus of rat brain at the end of the study. Hydro-alcoholic extract of E. alsinoides dose dependently prevented STZ induced cognitive impairment by reducing the oxidative stress, improving cholinergic function and preventing the increase in rho kinase expression. The results suggest an anti-Alzheimer potential of hydro-alcoholic extract of E. alsinoides.

Long-term administration of fasudil improves cardiomyopathy in streptozotocin-induced diabetic rats

Inhibition of Rho kinase (ROCK) has been shown to improve diabetic-related disorders. In this study, the cardio-protective effects and potential mechanisms of fasudil, a selective ROCK inhibitor, on diabetic cardiomyopathy were investigated in a streptozotocin (STZ)-induced diabetic rat model. Eight weeks after diabetes was induced by a single tail vein injection of 60 mg/kg STZ, rats were administered long-term fasudil or captopril as a control over a four-week period. Similar to the effect of captopril, fasudil treatment significantly protected against STZ-induced hemodynamic, histopathologic changes and decreased serum lactate dehydrogenase and creatine phosphokinase. Moreover, fasudil significantly down-regulated ROCK I mRNA expression and ROCK activity, reduced cardiac collagen deposition, and decreased the incidence of apoptosis and ratio of Bax/Bcl-2 protein expression. Additionally, fasudil potently elevated superoxide dismutase activity and suppressed the extent of lipid peroxidation in sera and hearts of diabetic rats. Our findings indicated that long-term treatment with fasudil could improve cardiac dysfunction, attenuate myocardial injury and prevent pathological changes in a rat model of diabetic cardiomyopathy. These effects could be attributed to regulation of antioxidative activities, suppression of myocardial hypertrophy, apoptosis, fibrosis and subsequent cardiac remodeling. These results may help to expand the clinical application of fasudil for diabetic cardiomyopathy.

Small-molecule-induced Rho-inhibition: NSAIDs after spinal cord injury

Limited axonal plasticity within the central nervous system (CNS) is a major restriction for functional recovery after CNS injury. The small GTPase RhoA is a key molecule of the converging downstream cascade that leads to the inhibition of axonal re-growth. The Rho-pathway integrates growth inhibitory signals derived from extracellular cues, such as chondroitin sulfate proteoglycans, Nogo-A, myelin-associated glycoprotein, oligodendrocyte-myelin glycoprotein, Ephrins and repulsive guidance molecule-A, into the damaged axon. Consequently, the activation of RhoA results in growth cone collapse and finally outgrowth failure. In turn, the inhibition of RhoA-activation blinds the injured axon to its growth inhibitory environment resulting in enhanced axonal sprouting and plasticity. This has been demonstrated in various CNS-injury models for direct RhoA-inhibition and for downstream/upstream blockade of the RhoA-associated pathway. In addition, RhoA-inhibition reduces apoptotic cell death and secondary damage and improves locomotor recovery in clinically relevant models after experimental spinal cord injury (SCI). Unexpectedly, a subset of "small molecules" from the group of non-steroid anti-inflammatory drugs, particularly the FDA-approved ibuprofen, has recently been identified as (1) inhibiting RhoA-activation, (2) enhancing axonal sprouting/regeneration, (3) protecting "tissue at risk" (neuroprotection) and (4) improving motor recovery confined to realistic therapeutical time-frames in clinically relevant SCI models. Here, we survey the effect of small-molecule-induced RhoA-inhibition on axonal plasticity and neurofunctional outcome in CNS injury paradigms. Furthermore, we discuss the body of preclinical evidence for a possible clinical translation with a focus on ibuprofen and illustrate putative risks and benefits for the treatment of acute SCI.

Rho kinase inhibition by fasudil exerts antioxidant effects in hypercholesterolemic rats

1. The inhibition of Rho kinase (ROCK) ameliorates many cardiovascular dysfunctions, but the role of ROCK in oxidative stress in hypercholesterolemic rats has not been explored. The aim of the current study was to investigate the antioxidant effects and the potential related mechanisms of fasudil, a selective ROCK inhibitor, in high-cholesterol diet (HCD)-induced hypercholesterolemic rats. 2. Hypercholesterolemia was induced in rats by feeding with a HCD for 4 weeks. Starting from day 15, physiological saline (1 mL/100 g) or ROCK inhibitor, fasudil (10 or 30 mg/kg), was injected intraperitoneally for another 14 days. 3. The results showed that fasudil significantly suppressed ROCK activity, potently elevated the activities of antioxidant enzymes and the expression of endothelial nitric oxide synthase, as well as the concentration of nitric oxide in the serum and cardiac tissue. In addition, fasudil notably suppressed the extent of lipid peroxidation and attenuated the histopathological changes in the heart and liver of hypercholesterolemic rats. 4. These antioxidant effects of fasudil suggest that ROCK activation is involved in oxidative stress in hypercholesterolemic rats.

Gypenoside attenuates white matter lesions induced by chronic cerebral hypoperfusion in rats

Cerebral white matter lesions (WMLs) are frequently observed in vascular dementia and Alzheimer's disease and are believed to be responsible for cognitive dysfunction. The cerebral WMLs are most likely caused by chronic cerebral hypoperfusion and can be experimentally induced by permanent bilateral common carotid artery occlusion (BCCAO) in rats. Previous studies found the involvement of oxidative stress and astrocytic activation in the cerebral WMLs of BCCAO rats. Gypenoside (GP), a pure component extracted from the Gyrostemma pentaphyllum Makino, a widely reputed medicinal plants in China, has been reported to have some neuroprotective effects via anti-oxidative stress and anti-inflammatory mechanisms. In the present study, we investigated the protective effect of GP against cerebral WMLs and the underlying mechanisms for its inhibition of cognitive decline in BCCAO rats. Adult male Sprague-Dawley rats were orally administered daily doses of 200 and 400mg/kg GP for 33 days after BCCAO, and spatial learning and memory were assessed using the Morris water maze. Following behavioral testing, oxygen free radical levels and antioxidative capability were measured biochemically. The levels of lipid peroxidation and oxidative DNA damage were also assessed by immunohistochemical staining for 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine, respectively. Activated astrocytes were also assessed by immunohistochemical staining and Western blotting with GFAP antibodies. The morphological changes were stained with Klüver-Barrera. Rats receiving 400mg/kg GP per day performed significantly better in tests for spatial learning and memory than saline-treated rats. GP 400mg/kg per day were found to markedly scavenge oxygen free radicals, enhance antioxidant abilities, decrease lipid peroxide production and oxidative DNA damage, and inhibit the astrocytic activation in corpus callosum and optic tract in BCCAO rats. However, GP 200mg/kg per day had no significant effects. GP may have therapeutic potential for treating dementia induced by chronic cerebral hypoperfusion and further evaluation is warranted.

Fasudil protects hippocampal neurons against hypoxia-reoxygenation injury by suppressing microglial inflammatory responses in mice

Rho kinase (ROCK) may play an important role in regulating biological events of cells, including proliferation, differentiation and survival/death. Blockade of ROCK promotes axonal regeneration and neuron survival in vivo and in vitro, thereby exhibiting potential clinical applications in spinal cord damage and stroke. Our previous studies have demonstrated that Fasudil, a selective ROCK inhibitor, induced neuroprotection in vitro. Here we used an in vivo model of hypoxia/reoxygenation (H/R) injury to examine the neuroprotective effect of Fasudil, and explore its possible mechanism(s) in vivo. H/R resulted in the loss of hippocampal neurons, accompanied by increased apoptosis of neurons in hippocampus. The expression of ROCK II and activity of ROCK in the brain were increased after H/R, and located only in microglia, but not in astrocytes and neurons. The administration of Fasudil inhibited the activity of ROCK in brain tissue and cultured microglia, and protected hippocampal neurons against H/R injury. Further immunohistochemical analysis and cytokine determination revealed that Fasudil inhibited inducible nitric oxide synthase immunoreactivity in microglia and pro-inflammatory factors in brain tissue after H/R, which is consistent with the observation wherein Fasudil reduced the pro-inflammatory factors nitric oxide, IL-1β, IL-6 and TNF-, and increased anti-inflammatory factor IL-10 in cultured microglia under normoxic or hypoxic conditions. Our results indicate that inhibition of ROCK by Fasudil may represent a useful therapeutic perspective by inhibiting microglial inflammatory responses in the CNS.

Targeting cerebrovascular Rho-kinase in stroke

BACKGROUND

Rho and Rho-associated kinase (ROCK) play pivotal roles in pathogenesis of vascular diseases including stroke. ROCK is expressed in all cell types relevant to stroke, and regulates a range of physiological processes.

OBJECTIVE

To provide an overview of ROCK as an experimental therapeutic target in cerebral ischemia, and the translational opportunities and obstacles in the prophylaxis and treatment of stroke.

METHODS

Relevant literature was reviewed.

RESULTS

ROCK activity is upregulated in chronic vascular risk factors such as diabetes, hyperlipidemia and hypertension, and more acutely by cerebral ischemia. ROCK activation is predicted to increase the risk of cerebral ischemia, and worsen the ischemic tissue outcome and functional recovery. Evidence suggests that ROCK inhibition is protective in models of cerebral ischemia. The benefit is mediated through multiple mechanisms.

CONCLUSION

ROCK is a promising therapeutic target in all stages of stroke.

Inhibition of intracellular Ca2+ release by a Rho-kinase inhibitor for the treatment of ischemic damage in primary cultured rat hippocampal neurons

The effects of hydroxy fasudil, a specific Rho-kinase inhibitor, on behavior and brain neuronal activity in animal studies have been described previously. However, whether a Rho-kinase inhibitor can directly protect neurons against ischemic damage and the molecular mechanisms underlying these effects are poorly understood. The present work was designed to investigate the effect of hydroxy fasudil against oxygen-glucose deprivation (OGD) induced acute neuronal injury and the underlying mechanisms in vitro. Pretreatment with hydroxy fasudil at 5 and 10 microM could concentration-dependently improve cell viability and decrease Lactate dehydrogenase (LDH) level in extracellular solution of neurons suffered from OGD either in Ca(2+)-containing or Ca(2+)-free culture medium. Moreover, we found that abnormal elevation of extracellular glutamate (Glu) level induced by OGD was markedly repressed by hydroxy fasudil as measured by high performance liquid chromatography (HPLC). Using Fura-2 based calcium imaging techniques, we further demonstrated that preincubation with hydroxy fasudil suppressed the increase of [Ca(2+)](i) induced by 50 microM Glu and 20 microM ATP, but had no effect on the increase of [Ca(2+)](i) induced by 50 mM KCl. These data demonstrated that the neuroprotective effect of hydroxy fasudil was attributed to repressing Glu excitotoxicity and ischemic induced calcium overload by inhibiting Ca(2+) release from Ca(2+) stores rather than by inhibiting Ca(2+) influx via receptor-operated or voltage-dependent calcium channel.

Guattegaumerine protects primary cultured cortical neurons against oxidative stress injury induced by hydrogen peroxide concomitant with serum deprivation

Guattegaumerine is a natural product with characteristics of being lipophilic and reaching high concentration in the brain, but its function in the central nervous system has not yet been observed. This study was designed to evaluate the neuroprotective effects of guattegaumerine on rat primary cultured cortical neurons. Following a 24-h exposure of the cells to combined serum-starvation and hydrogen peroxide, a significant augment in neuron damage as determined by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release were observed. Preincubation of guattegaumerine dramatically improved the cell viability and inhibited LDH release. Preincubation of guattegaumerine also dramatically inhibited malondialhehyde (MDA) production and elevated the decreased total antioxidative capacity in cells caused by the combined injury. Results of flow cytometry and immunohistochemistry showed that pre-addition of guattegaumerine interrupted the apoptosis of the neurons, reversed the up regulation of the pro-apoptotic gene (Bax) and the down regulation of the anti-apoptotic gene (Bcl-2). Furthermore, guattegaumerine suppressed the increase of intracellular calcium ([Ca(2+)](i)) stimulated by either H(2)O(2) or KCl in Ca(2+)-containing extracellular solutions, and high concentration of 2.5 microM guattegaumerine also suppressed the increase of [Ca(2+)](i) induced by H(2)O(2) in Ca(2+)-free solution. These observations suggested that guattegaumerine may possess potential protection against oxidative stress injury, which might be beneficial for neurons.

Neuroprotective potential of fasudil mesylate in brain ischemia-reperfusion injury of rats

We previously reported that inhibition of Rho-kinase (ROCK) by hydroxyl fasudil improves cognitive deficit and neuronal damage in rats with chronic cerebral ischemia (Huang et al., Cell Mol Neurobiol 28:757-768, 2008). In this study, fasudil mesylate (FM) was investigated for its neuroprotective potential in rats with ischemia following middle cerebral artery occlusion (MCAO) and reperfusion. The effect of fasudil mesylate was also studied in rat brain cortical and hippocampal slices treated with oxygen-glucose deprivation (OGD) injury. Gross anatomy showed that cerebral infarct size, measured with 2,3,5-triphenyltetrazolium chloride (TTC) staining, was significantly smaller in the FM-treated than in the non-FM-treated ischemic rats. In the brain regions vulnerable to ischemia of ischemic rats, fasudil mesylate was also found to significantly restore the enzyme protein expression level of endothelial nitric oxide synthase (eNOS), which was decreased in ischemia. However, it remarkably reduced the protein synthesis of inducible nitric oxide synthase (iNOS) that was induced by ischemia and reperfusion. In rat brain slices treated with OGD injury, fasudil mesylate increased the neuronal cell viability by 40% for cortex and by 61% for hippocampus, respectively. Finally, in the presence of OGD and fasudil mesylate, superoxide dismutase (SOD) activity was increased by 50% for cortex and by 58% for hippocampus, compared to OGD only group. In conclusion, our in vivo study showed that fasudil mesylate not only decreased neurological deficit but also reduced cerebral infarct size, possibly and at least partially by augmenting eNOS protein expression and inhibiting iNOS protein expression after ischemia-reperfusion.