Apoptosis: A Target for Neuroprotection

Neuroprotective Effects of Coenzyme Q10 and Ozone Therapy on Experimental Traumatic Spinal Cord Injuries in Rats

OBJECTIVE

This study investigates the neuroprotective effects and functional recovery potential of Coenzyme Q10 (CoQ10) and ozone therapy in spinal cord injury (SCI).

MATERIAL AND METHODS

In this study, 40 female Sprague-Dawley rats were divided into 5 groups of 8. Surgical procedures induced spinal cord trauma in all groups, except the control group. The ozone group received 0.7 mg/kg rectal ozone daily for 7 days, starting 1 hour postspinal cord trauma. The CoQ10 group was administered 120 mg/kg CoQ10 orally once daily for 7 days, beginning 24 hours prior to trauma. The CoQ10 + ozone group received both treatments. Examinations included a modified Tarlov scale and inclined plane test on days 1, 3, 5, and 7. Malondialdehyde (MDA) analysis was conducted on serum samples, and assessments of caspase-3, Bcl-2, and Bax levels were performed on tissue samples. Additionally, a comprehensive examination analyzed histopathological and ultrastructural changes.

RESULTS

After SCI, there was a statistically significant increase in serum MDA, tissue caspase-3, and Bax levels (MDA P < 0.001, caspase-3 P < 0.001, Bax P = 0.003). In the CoQ10 + ozone group, serum MDA (P = 0.002), tissue caspase-3 (P = 0.001), and Bax (P = 0.030) levels were significantly lower compared to the trauma group. Tissue Bcl-2 levels were also significantly higher (P = 0.019). The combined treatment group demonstrated improved histopathological, ultrastructural, and neurological outcomes.

CONCLUSIONS

This study shows that CoQ10 + ozone therapy in traumatic SCI demonstrates neuroprotective effects via antioxidant and antiapoptotic mechanisms. The positive effects on functional recovery are supported by data from biochemical, histopathological, ultrastructural, and neurological examinations.

Advancement in research on the role of the transient receptor potential vanilloid channel in cerebral ischemic injury (Review)

Stroke is a common critical disease occurring in middle-aged and elderly individuals, and is characterized by high morbidity, lethality and mortality. As such, it is of great concern to medical professionals. The aim of the present review was to investigate the effects of transient receptor potential vanilloid (TRPV) subtypes during cerebral ischemia in ischemia-reperfusion animal models, oxygen glucose deprivation and in other administration cell models in vitro to explore new avenues for stroke research and clinical treatments. TRPV1, TRPV2 and TRPV4 employ different methodologies by which they confer protection against cerebral ischemic injury. TRPV1 and TRPV4 are likely related to the inhibition of inflammatory reactions, neurotoxicity and cell apoptosis, thus promoting nerve growth and regulation of intracellular calcium ions (Ca2+). The mechanisms of neuroprotection of TRPV1 are the JNK pathway, N-methyl-D-aspartate (NMDA) receptor and therapeutic hypothermia. The mechanisms of neuroprotection of TRPV4 are the PI3K/Akt pathways, NMDA receptor and p38 MAPK pathway, amongst others. The mechanisms by which TRPV2 confers its protective effects are predominantly connected with the regulation of nerve growth factor, MAPK and JNK pathways, as well as JNK-dependent pathways. Thus, TRPVs have the potential for improving outcomes associated with cerebral ischemic or reperfusion injuries. The protection conferred by TRPV1 and TRPV4 is closely related to cellular Ca2+ influx, while TRPV2 has a different target and mode of action, possibly due to its expression sites. However, in light of certain contradictory research conclusions, further experimentation is required to clarify the mechanisms and specific pathways by which TRPVs act to alleviate nerve injuries.

Availability of neuregulin-1beta1 protects neurons in spinal cord injury and against glutamate toxicity through caspase dependent and independent mechanisms

Spinal cord injury (SCI) causes sensorimotor and autonomic impairment that partly reflects extensive, permanent loss of neurons at the epicenter and penumbra of the injury. Strategies aimed at enhancing neuronal protection are critical to attenuate neurodegeneration and improve neurological recovery after SCI. In rat SCI, we previously uncovered that the tissue levels of neuregulin-1beta 1 (Nrg-1β1) are acutely and persistently downregulated in the injured spinal cord. Nrg-1β1 is well-known for its critical roles in the development, maintenance and physiology of neurons and glia in the developing and adult spinal cord. However, despite this pivotal role, Nrg-1β1 specific effects and mechanisms of action on neuronal injury remain largely unknown in SCI. In the present study, using a clinically-relevant model of compressive/contusive SCI in rats and an in vitro model of glutamate toxicity in primary neurons, we demonstrate Nrg-1β1 provides early neuroprotection through attenuation of reactive oxygen species, lipid peroxidation, necrosis and apoptosis in acute and subacute stages of SCI. Mechanistically, availability of Nrg-1β1 following glutamate challenge protects neurons from caspase-dependent and independent cell death that is mediated by modulation of mitochondria associated apoptotic cascades and MAP kinase and AKT signaling pathways. Altogether, our work provides novel insights into the role and mechanisms of Nrg-1β1 in neuronal injury after SCI and introduces its potential as a new neuroprotective target for this debilitating neurological condition.

Benzoinum from Styrax tonkinensis (Pierre) Craib ex Hart exerts a NVU protective effect by inhibiting cell apoptosis in cerebral ischaemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

Benzoinum (Styraceae) is a traditional Chinese medicine used to treat stroke and other cardio-cerebrovascular diseases for thousands of years. Benzoinum has also proven to have diverse pharmacological activity, but the neuroprotection mechanism of apoptosis in ischaemic stroke was not determined.

AIM OF THIS STUDY

To investigate the protective effect of a neurovascular unit (NVU) and the mechanisms of benzoinum on cerebral ischaemic rats.

MATERIALS AND METHODS

The neuroprotective activity of benzoinum against middle cerebral artery occlusion (MCAO)-induced cerebral ischaemic injury. Neurological scores, 2,3,5-Triphenyltetrazolium chloride (TTC) staining, and hematoxylin-eosin staining (HE) staining were conducted to evaluate the neurological damage. Infarction rate and denatured cell index (DCI) were also calculated. The ultrastructure of neuron and blood-brain-barrier (BBB) was observed by transmission electron microscopy (TEM). Immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect Bax, Bcl-2 and Caspase 3 expression. Furthermore, Claudin 5 also was detected through immunohistochemistry.

RESULTS

Benzoinum could significantly improve neurological function score and reduce cerebral infarction rate and DCI. In addition, benzoinum alleviated pathomorphological change and apoptosis in the brain tissue of MCAO rats. The results of TEM and claudin 5 expression of immunohistochemistry showed that benzoinum could play a neuroprotective effect in NVU. Also, benzoinum-enhanced Bcl2, and reduced Bax and Bax/Bcl-2 and Caspase 3, suggest that benzoinum provided a neuroprotective effect by inhibited cell apoptosis.

CONCLUSION

Benzoinum could play a neuroprotective role and regulate apoptosis for repair and stabilisation of NVU. This anti-apoptosis activity might be associated with the downregulation of Bax and Caspase 3, and the upregulation of Bcl2. Our present findings provide a promising medication for the treatment of ischaemic stroke.

miR-34a-5p and miR-125b-5p attenuate Aβ-induced neurotoxicity through targeting BACE1

BACKGROUND

Accumulation of β-amyloid (Aβ) could induce neurotoxicity in Alzheimer's disease (AD). microRNA (miR)-34a-5p and miR-125b-5p have been reported to be aberrantly expressed in AD patients. However, the roles and mechanisms of these two miRNAs in AD remain poorly understood.

METHODS

Serum samples of 27 AD patients were collected. Primary mouse cortical neurons (MCN) and Neuro2a (N2a) cells were incubated with Aβ. The expression levels of miR-34a-5p, miR-125b-5p and β-site amyloid precursor protein cleaving enzyme 1 (BACE1) were detected by quantitative real-time polymerase chain reaction and western blot. The effect of miRNAs or epigallocatechin-3-gallate (EGCG) on Aβ-induced neurotoxicity was investigated by cell viability, Caspase 3 activity, apoptosis and intracellular ROS production. The interaction between BACE1 and miR-34a-5p or miR-125b-5p was analyzed by luciferase reporter assay.

RESULTS

miR-34a-5p and miR-125b-5p levels were decreased and BACE1 mRNA expression was increased in AD patients and Aβ-treated MCN and N2a cells. Addition of miR-34a-5p or miR-125b-5p attenuated Aβ-induced apoptosis and oxidative stress. BACE1 acted as a target of miR-34a-5p and miR-125b-5p and its restoration weakened the effect of miR-34a-5p or miR-125b-5p on Aβ-induced neurotoxicity. Moreover, EGCG could mitigate Aβ-induced neurotoxicity, which might be associated with miR-34a-5p and miR-125b-5p.

CONCLUSION

miR-34a-5p and miR-125b-5p inhibited Aβ-induced neurotoxicity by decreasing apoptosis and oxidative stress via targeting BACE1, providing novel targets for treatment of AD.

Bisperoxovanadium protects against spinal cord injury by regulating autophagy via activation of ERK1/2 signaling

Background

Spinal cord injury (SCI) is a disease of the central nervous system with few restorative treatments. Autophagy has been regarded as a promising therapeutic target for SCI. The inhibitor of phosphatase and tensin homolog deleted on chromosome ten (PTEN) bisperoxovanadium (bpV[pic]) had been claimed to provide a neuroprotective effect on SCI; but the underlying mechanism is still not fully understood.

Materials and methods

Acute SCI model were generated with SD Rats and were treated with control, acellular spinal cord scaffolds (ASC) obtained from normal rats, bpV(pic), and combined material of ASC and bpV(pic). We used BBB score to assess the motor function of the rats and the motor neurons were stained with Nissl staining. The expressions of the main autophagy markers LC3B, Beclin1 and P62, expressions of apoptosis makers Bax, Bcl2, PARP and Caspase 3 were detected with IF or Western Blot analysis.

Results

The bpV(pic) showed significant improvement in functional recovery by activating autophagy and accompanied by decreased neuronal apoptosis; combined ASC with bpV(pic) enhanced these effects. In addition, after treatment with ERK1/2 inhibitor SCH772984, we revealed that bpV(pic) promotes autophagy and inhibits apoptosis through activating ERK1/2 signaling after SCI.

Conclusion

These results illustrated that the bpV(pic) protects against SCI by regulating autophagy via activation of ERK1/2 signaling.

Monoamine oxidase-B inhibitors as potential neurotherapeutic agents: An overview and update

Monoamine oxidase (MAO) inhibitors have made significant contributions and remain an indispensable approach of molecular and mechanistic diversity for the discovery of antineurodegenerative drugs. However, their usage has been hampered by nonselective and/or irreversible action which resulted in drawbacks like liver toxicity, cheese effect, and so forth. Hence, the search for selective MAO inhibitors (MAOIs) has become a substantial focus in current drug discovery. This review summarizes our current understanding on MAO-A/MAO-B including their structure, catalytic mechanism, and biological functions with emphases on the role of MAO-B as a potential therapeutic target for the development of medications treating neurodegenerative disorders. It also highlights the recent developments in the discovery of potential MAO-B inhibitors (MAO-BIs) belonging to diverse chemical scaffolds, arising from intensive chemical-mechanistic and computational studies documented during past 3 years (2015-2018), with emphases on their potency and selectivity. Importantly, readers will gain knowledge of various newly established MAO-BI scaffolds and their development potentials. The comprehensive information provided herein will hopefully accelerate ideas for designing novel selective MAO-BIs with superior activity profiles and critical discussions will inflict more caution in the decision-making process in the MAOIs discovery.

P2X7 Receptor-Associated Programmed Cell Death in the Pathophysiology of Hemorrhagic Stroke

Hemorrhagic stroke is a life-threatening disease characterized by a sudden rupture of cerebral blood vessels, and cell death is widely believed to occur after exposure to blood metabolites or subsequently damaged cells. Recently, programmed cell death, such as apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis, has been demonstrated to play crucial roles in the pathophysiology of stroke. However, the detailed mechanisms of these novel kinds of cell death are still unclear. The P2X7 receptor, previously known for its cytotoxic activity, is an ATP-gated, nonselective cation channel that belongs to the family of ionotropic P2X receptors. Evolving evidence indicates that the P2X7 receptor plays a pivotal role in central nervous system pathology; genetic deletion and pharmacological blockade of the P2X7 receptor provide neuroprotection in various neurological disorders, including intracerebral hemorrhage and subarachnoid hemorrhage. The P2X7 receptor may regulate programmed cell death via (I) exocytosis of secretory lysosomes, (II) exocytosis of autophagosomes or autophagolysosomes during formation of the initial autophagic isolation membrane or omegasome, and (III) direct release of cytosolic IL-1β secondary to regulated cell death by pyroptosis or necroptosis. In this review, we present an overview of P2X7 receptor- associated programmed cell death for further understanding of hemorrhagic stroke pathophysiology, as well as potential therapeutic targets for its treatment.

Epoxyeicosatrienoic Acid Inhibits the Apoptosis of Cerebral Microvascular Smooth Muscle Cells by Oxygen Glucose Deprivation via Targeting the JNK/c-Jun and mTOR Signaling Pathways

As a component of the neurovascular unit, cerebral smooth muscle cells (CSMCs) are an important mediator in the development of cerebral vascular diseases such as stroke. Epoxyeicosatrienoic acids (EETs) are the products of arachidonic acid catalyzed by cytochrome P450 epoxygenase. EETs are shown to exert neuroprotective effects. In this article, the role of EET in the growth and apoptosis of CSMCs and the underlying mechanisms under oxygen glucose deprivation (OGD) conditions were addressed. The viability of CMSCs was decreased significantly in the OGD group, while different subtypes of EETs, especially 14,15-EET, could increase the viability of CSMCs under OGD conditions. RAPA (serine/threonine kinase Mammalian Target of Rapamycin), a specific mTOR inhibitor, could elevate the level of oxygen free radicals in CSMCs as well as the anti-apoptotic effects of 14,15-EET under OGD conditions. However, SP600125, a specific JNK (c-Jun N-terminal protein kinase) pathway inhibitor, could attenuate oxygen free radicals levels in CSMCs as well as the anti-apoptotic effects of 14,15-EET under OGD conditions. These results strongly suggest that EETs exert protective functions during the growth and apoptosis of CSMCs, via the JNK/c-Jun and mTOR signaling pathways in vitro. We are the first to disclose the beneficial roles and underlying mechanism of 14,15-EET in CSMC under OGD conditions.

Caspase-3 inhibitor prevents the apoptosis of brain tissue in rats with acute cerebral infarction

The aim of the present study was to investigate the effect of the caspase-3 inhibitor z-DEVD-fmk on the apoptosis of the brain tissues of rats with acute cerebral infarction. Middle cerebral artery occlusion was used to establish a rat model of infarction, and the rats were randomly divided into a sham group (n=15), model group (n=15) and treatment group (n=15). z-DEVD-fmk (2.5 µg/kg) was injected into the intracranial artery of rats in the treatment group, while the same volume of phosphate-buffered saline solution was administered to the rats of the sham and model groups. After 48 h, all rats were sacrificed and their brain tissues were removed. The caspase-3 mRNA level, protein level and activity, brain cell apoptosis index and infarction scope of the three groups were analyzed. Neurological impairment was also assessed. At 48 h after model establishment, the caspase-3 mRNA and protein levels in the brain tissues of the model group were significantly higher than those of the sham group, and those in the treatment group were significantly lower than those in the model group (P<0.05); however, they remained significantly higher than those in the sham group. Caspase-3 activity in the model group was significantly higher than that in the sham group, and treatment with the caspase-3 inhibitor significantly reduced caspase-3 activity compared with that in the model group (P<0.05). The apoptosis index and infarction scope in the model and treatment groups were significantly increased compared with those in the sham group, and were significantly lower in the treatment group than in the model group (P<0.05). The neurological impairment of rats in the model and treatment groups was increased significantly compared with that in the sham group, and the treatment group exhibited a significantly lower level of neurological impairment than the model group (P<0.05). In conclusion, the caspase-3 inhibitor z-DEVD-fmk effectively inhibited apoptosis and delayed the necrosis of brain tissue cells in rats with acute cerebral infarction, and had certain protective effects on brain tissue.

Neuroprotective effect of weak static magnetic fields in primary neuronal cultures

Low intensity static magnetic fields (SMFs) interact with various biological tissues including the CNS, thereby affecting key biological processes such as gene expression, cell proliferation and differentiation, as well as apoptosis. Previous studies describing the effect of SMFs on apoptotic cell death in several non-neuronal cell lines, emphasize the importance of such a potential modulation in the case of neurodegenerative disorders, where apoptosis constitutes a major route via which neurons degenerate and die. In this study, we examine the effect of SMFs on neuronal survival in primary cortical and hippocampal neurons that constitute a suitable experimental system for modeling the neurodegenerative state in vitro. We show that weak SMF exposure interferes with the apoptotic programing in rat primary cortical and hippocampal neurons, thereby providing protection against etoposide-induced apoptosis in a dose- and time-dependent manner. Primary cortical neurons exposed to SMF (50G) for 7days exhibited a 57.1±6.3% decrease in the percentage of cells undergoing apoptosis induced by etoposide (12μM), accompanied by a marked decrease in the expression of the pro-apoptotic markers: cleaved poly ADP ribose polymerase-1, cleaved caspase-3, active caspase-9 and the phospho-histone H2A variant (Ser139) by 41.0±5.0%, 81.2±5.0%, 72.9±6.4%, 42.75±2.9%, respectively, and by a 57.2±1.0% decrease in the extent of mitochondrial membrane potential collapse. Using the L-type voltage-gated Ca(2+) channel inhibitor nifedipine, which is selective to Ca(2+) influx through Cav1.2, we found that the anti-apoptotic effect of SMFs was mediated by Ca(2+) influx through these channels. Our findings demonstrating altered Ca(2+)-influx in response to thapsigargin stimulation in SMF-exposed cortical neurons, along with enhanced inhibition of KCl-induced Ca(2+)-influx through Cav1.2 channels and enhanced expression of Cav1.2 and Cav1.3 channels, allude to the involvement of voltage- and store-operated Ca(2+) channels in various aspects of the protective effect exerted by SMFs. These findings show the potential susceptibility of the CNS to weak SMF exposure and have implications for the design of novel strategies for the treatment and/or prevention of neurodegenerative diseases.

The effects of N-acetyl-cysteine and acetyl-L-carnitine on neural survival, neuroinflammation and regeneration following spinal cord injury

Traumatic spinal cord injury induces a long-standing inflammatory response in the spinal cord tissue, leading to a progressive apoptotic death of spinal cord neurons and glial cells. We have recently demonstrated that immediate treatment with the antioxidants N-acetyl-cysteine (NAC) and acetyl-l-carnitine (ALC) attenuates neuroinflammation, induces axonal sprouting, and reduces the death of motoneurons in the vicinity of the trauma zone 4weeks after initial trauma. The objective of the current study was to investigate the effects of long-term antioxidant treatment on the survival of descending rubrospinal neurons after spinal cord injury in rats. It also examines the short- and long-term effects of treatment on apoptosis, inflammation, and regeneration in the spinal cord trauma zone. Spinal cord hemisection performed at the level C3 induced a significant loss of rubrospinal neurons 8 weeks after injury. At 2 weeks, an increase in the expression of the apoptosis-associated markers BCL-2-associated X protein (BAX) and caspase 3, as well as the microglial cell markers OX42 and ectodermal dysplasia 1 (ED1), was seen in the trauma zone. After 8 weeks, an increase in immunostaining for OX42 and the serotonin marker 5HT was detected in the same area. Antioxidant therapy reduced the loss of rubrospinal neurons by approximately 50%. Treatment also decreased the expression of BAX, caspase 3, OX42 and ED1 after 2 weeks. After 8 weeks, treatment decreased immunoreactivity for OX42, whereas it was increased for 5HT. In conclusion, this study provides further insight in the effects of treatment with NAC and ALC on descending pathways, as well as short- and long-term effects on the spinal cord trauma zone.

n-butylidenephthalide protects against dopaminergic neuron degeneration and α-synuclein accumulation in Caenorhabditis elegans models of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common degenerative disorder of the central nervous system that impairs motor skills and cognitive function. To date, the disease has no effective therapies. The identification of new drugs that provide benefit in arresting the decline seen in PD patients is the focus of much recent study. However, the lengthy time frame for the progression of neurodegeneration in PD increases both the time and cost of examining potential therapeutic compounds in mammalian models. An alternative is to first evaluate the efficacy of compounds in Caenorhabditis elegans models, which reduces examination time from months to days. n-Butylidenephthalide is the naturally-occurring component derived from the chloroform extract of Angelica sinensis. It has been shown to have anti-tumor and anti-inflammatory properties, but no reports have yet described the effects of n-butylidenephthalide on PD. The aim of this study was to assess the potential for n-butylidenephthalide to improve PD in C. elegans models.

METHODOLOGY/PRINCIPAL FINDINGS

In the current study, we employed a pharmacological strain that expresses green fluorescent protein specifically in dopaminergic neurons (BZ555) and a transgenic strain that expresses human α-synuclein in muscle cells (OW13) to investigate the antiparkinsonian activities of n-butylidenephthalide. Our results demonstrate that in PD animal models, n-butylidenephthalide significantly attenuates dopaminergic neuron degeneration induced by 6-hydroxydopamine; reduces α-synuclein accumulation; recovers lipid content, food-sensing behavior, and dopamine levels; and prolongs life-span of 6-hydroxydopamine treatment, thus revealing its potential as a possible antiparkinsonian drug. n-Butylidenephthalide may exert its effects by blocking egl-1 expression to inhibit apoptosis pathways and by raising rpn-6 expression to enhance the activity of proteasomes.

CONCLUSIONS/SIGNIFICANCE

n-Butylidenephthalide may be one of the effective neuroprotective agents for PD.

A novel compound PTIQ protects the nigral dopaminergic neurones in an animal model of Parkinson's disease induced by MPTP

BACKGROUND AND PURPOSE

In Parkinson's disease, the dopaminergic neurones in the substantia nigra undergo degeneration. While the exact mechanism for the degeneration is not completely understood, neuronal apoptosis and neuroinflammation are thought to be key contributors. We have recently established that MMP-3 plays crucial roles in dopaminergic cell death and microglial activation.

EXPERIMENTAL APPROACH

We tested the effects of 7-hydroxy-6-methoxy-2-propionyl-1,2,3,4-tetrahydroisoquinoline (PTIQ) on expression of MMP-3 and inflammatory molecules and dopaminergic cell death in vitro and in an animal model of Parkinson's disease, and Parkinson's disease-related motor deficits. The pharmacokinetic profile of PTIQ was also evaluated.

KEY RESULTS

PTIQ effectively suppressed the production of MMP-3 induced in response to cellular stress in the dopaminergic CATH.a cell line and prevented the resulting cell death. In BV-2 microglial cells activated with lipopolysaccharide, PTIQ down-regulated expression of MMP-3 along with IL-1β, TNF-α and cyclooxygenase-2 and blocked nuclear translocation of NF-κB. In the mouse model of Parkinson's disease ,induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), PTIQ attenuated the associated motor deficits, prevented neurodegeneration and suppressed microglial activation in the substantia nigra. Pharmacokinetic analysis showed it was relatively stable against liver microsomal enzymes, did not inhibit the cytochrome p450 isozymes or the hERG ion channel, exhibited no cytotoxicity on liver cells or lethality when administered at 1000 mg kg(-1) and entered the brain rather rapidly yielding a 28% brain:plasma ratio after i.p. injection.

CONCLUSIONS AND IMPLICATIONS

These results suggest PTIQ has potential as a candidate drug for disease-modifying therapy for Parkinson's disease.

Classification of scaffold-hopping approaches

The general goal of drug discovery is to identify novel compounds that are active against a preselected biological target with acceptable pharmacological properties defined by marketed drugs. Scaffold hopping has been widely applied by medicinal chemists to discover equipotent compounds with novel backbones that have improved properties. In this article we classify scaffold hopping into four major categories, namely heterocycle replacements, ring opening or closure, peptidomimetics and topology-based hopping. We review the structural diversity of original and final scaffolds with respect to each category. We discuss the advantages and limitations of small, medium and large-step scaffold hopping. Finally, we summarize software that is frequently used to facilitate different kinds of scaffold-hopping methods.

Amelioration of cerebral infarction and improvement of neurological deficit by a Korean herbal medicine, modified Bo-Yang-Hwan-O-Tang

OBJECTIVES

Modified Bo-Yang-Hwan-O-Tang (mBHT) is an improved herbal formula of BHT, which has been widely used to treat ischaemic stroke in East Asia, by the addition of five herbs having anti-ischaemic properties. In this study, we investigated whether mBHT would reduce cerebral ischaemic injury in rats.

METHODS

Sprague-Dawley rats were subjected to a 90-min middle cerebral artery occlusion (MCAO) and subsequent 22-h reperfusion. mBHT was administered either intraperitoneally twice 15 min before and 15 min after, or orally once 30 min or 120 min after the onset of MCAO (50 or 200 mg/kg each).

KEY FINDINGS

Intraperitoneal administration of mBHT markedly reduced the cerebral infarct size and neurological deficit caused by MCAO/reperfusion. mBHT treatment also significantly improved long-term survival rate after cerebral ischaemic injury. Oral administration of mBHT 30 min after ischaemia also markedly reduced the infarct size after cerebral ischaemia. The anti-ischaemic effect of mBHT was significantly, but not fully, reduced when mBHT-induced hypothermia was abolished. In cultured cortical neurons, we further found that mBHT decreased oxygen-glucose deprivation/re-oxygenation-evoked neuronal injury by inhibiting production of reactive oxygen species, decrease in mitochondrial transmembrane potential, and activation of caspase-3. However, mBHT did not inhibit N-Methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity.

CONCLUSIONS

Taken together, our data suggest that mBHT has multiple anti-ischaemic properties and would be a good therapeutic herbal prescription for the treatment of cerebral ischaemic stroke.

Inhibition of caspase-3-mediated apoptosis improves spinal cord repair in a regeneration-competent vertebrate system

Teleost fish exhibit an excellent potential for structural and functional recovery after CNS lesions. The function of apoptosis in the process of regeneration remains controversial. While some studies have identified this type of cell death as essential for successful regeneration, other investigations have suggested some degree of functional improvement after inhibition of apoptosis. In the present study, we examined whether inhibition of apoptosis immediately after injury can improve spinal cord regeneration. As a model system, we used Apteronotus leptorhynchus, a regeneration-competent weakly electric fish. To inhibit apoptosis, we employed 2,2'-methylenebis (1,3-cyclohexanedione) (M50054), a compound that prevents caspase-3 activation. Administration of this apoptosis inhibitor led to a significant reduction in the numbers of apoptotic cells at 24 h, 5 days, and 30 days after the lesion. Using triple immunolabeling, we identified a significant reduction in the level of apoptosis at 5 and 30 days after the lesion among the following cellular categories: cells generated shortly after the lesion, existing neurons, and newly differentiated neurons. This reduced rate of apoptosis led to an increase in the relative number of differentiating and surviving neurons at both 5 and 30 days post-injury, compared to the control groups. Functional regeneration, as indicated by the recovery rate of the amplitude of the electric organ discharge (EOD), was significantly improved within the first 20 days after the lesion in the fish treated with M50054. Our data provide the first evidence that modulation of caspase-3 activation can significantly improve neuroregeneration and functional recovery in a regeneration-competent organism.

Doxycycline is neuroprotective against nigral dopaminergic degeneration by a dual mechanism involving MMP-3

In Parkinson disease (PD), the dopaminergic (DAergic) neurons in the substantia nigra undergo degeneration. While the exact mechanism for the degeneration is still not completely understood, neuronal apoptosis and inflammation are thought to play roles. We have recently obtained evidence that matrix metalloproteinase (MMP)-3 plays a crucial role in the apoptotic signal in DAergic cells as well as activation of microglia. The present study tested whether doxycycline might modulate MMP-3 and provide neuroprotection of DAergic neurons. Doxycycline effectively suppressed the expression of MMP-3 induced in response to cellular stress in the DAergic CATH.a cells. This was accompanied by protection of CATH.a cells as well as primary cultured mesencephalic DAergic neurons via attenuation of apoptosis. The active form of MMP-3, released under the cell stress condition, was also decreased in the presence of doxycycline. In addition, doxycycline led to downregulation of MMP-3 in microglial BV-2 cells exposed to lipopolysaccharide (LPS). This was accompanied by suppression of production of nitric oxide and TNF-alpha, as well as gene expression of iNOS, TNF-alpha, IL-1beta, and COX-2. In vivo, doxycycline provided neuroprotection of the nigral DAergic neurons following MPTP treatment, as assessed by tyrosine hydroxylase immunocytochemistry and silver staining, and suppressed microglial activation and astrogliosis as assessed by Iba-1 and GFAP immunochemistry, respectively. Taken together, doxycycline showed neuroprotective effect on DAergic system both in vitro and in vivo and this appeared to derive from anti-apoptotic and anti-inflammatory mechanisms involving downregulation of MMP-3.

Is xenon a future neuroprotectant?

Acute neuronal injury has devastating consequences with increased risks of morbidity and mortality. Among its survivors, neurological deficit is associated with loss of function, independence and quality of life. Currently, there is a distinctive lack of effective clinical strategies to obviate this problem. Xenon, a noble gas with anesthetic properties, exhibits neuroprotective effects. It is efficacious and nontoxic and has been used safely in clinical settings involving both anesthetic and imaging applications in patients of all ages. Xenon blocks the NMDA subtype of the glutamate receptor, a pivotal step in the pathway towards neuronal death. The preclinical data obtained from animal models of stroke, neonatal asphyxia and global ischemia induced by cardiac arrest, as well as recent data of traumatic brain injury, revealed that xenon is a potentially ideal candidate as a neuroprotectant. In addition, recent studies demonstrated that xenon can uniquely prevent anesthetic-induced neurodegeneration in the developing brain. Thus, clinical studies are urgently required to investigate the neuroprotective effects of xenon in the clinical setting of brain damage.

Molecular mechanisms of spinal cord dysfunction and cell death in the spinal hyperostotic mouse: implications for the pathophysiology of human cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in adults in Western society. Paradoxically, relatively little is known about the pathobiological mechanisms associated with the progressive loss of neural tissue in the spinal cord of CSM patients. In this report we have utilized the twy/twy mutant mouse, which develops ossification of the ligamentum flavum at C2-C3 and exhibits progressive paralysis. This animal model represents an excellent in vivo model of CSM. This study reports novel evidence, which demonstrates that chronic extrinsic cervical spinal cord compression leads to Fas-mediated apoptosis of neurons and oligodendrocytes which is associated with activation of caspase-8, -9 and -3 and progressive neurological deficits. While surgical decompression will remain the mainstay of management of CSM, molecular therapies, which target Fas-mediated apoptosis could show promise as a complementary approach to maximize neurological recovery in this common spinal cord condition.

Zebrafish: a predictive model for assessing drug-induced toxicity

The zebrafish model organism is increasingly used for assessing drug toxicity and safety and numerous studies confirm that mammalian and zebrafish toxicity profiles are strikingly similar. This transparent vertebrate offers several compelling experimental advantages, including convenient drug delivery and low cost. Although full validation will require assessment of a large number of compounds from diverse classes, zebrafish can be used to eliminate potentially unsafe compounds rapidly in the early stages of drug development and to prioritize compounds for further preclinical and clinical studies. Adaptation of conventional instrumentation combined with new nanotechnology developments will continue to expand use of zebrafish for drug screening.

Neuronal apoptosis in neurodegeneration

Apoptosis mediates the precise and programmed natural death of neurons and is a physiologically important process in neurogenesis during maturation of the central nervous system. However, premature apoptosis and/or an aberration in apoptosis regulation is implicated in the pathogenesis of neurodegeneration, a multifaceted process that leads to various chronic disease states, such as Alzheimer's (AD), Parkinson's (PD), Huntington's (HD) diseases, amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), and diabetic encephalopathy. The current review focuses on two major areas (a) the fundamentals of apoptosis, which includes elements of the apoptotic machinery, apoptosis inducers, and emerging concepts in apoptosis research, and (b) apoptotic involvement in neurodegenerative disorders, neuroprotective treatment strategies/modalities, and the mechanisms of, and signaling in, neuronal apoptosis. Current and new experimental models for apoptosis research in neurodegenerative diseases are also discussed.

Neurotoxicity assessment using zebrafish

INTRODUCTION

Transparency is a unique attribute of zebrafish that permits direct assessment of drug effects on the nervous system using whole mount antibody immunostaining and histochemistry.

METHODS

To assess pharmacological effects of drugs on the optic nerves, motor neurons, and dopaminergic neurons, we performed whole mount immunostaining and visualized different neuronal cell types in vivo. In addition, we assessed neuronal apoptosis, proliferation, oxidation and the integrity of the myelin sheath using TUNEL staining, immunostaining and in situ hybridization. The number of dopaminergic neurons was examined and morphometric analysis was performed to quantify the staining signals for myelin basic protein and apoptosis.

RESULTS

We showed that compounds that induce neurotoxicity in humans caused similar neurotoxicity in zebrafish. For example, ethanol induced defects in optic nerves and motor neurons and affected neuronal proliferation; 6-hydroxydopamine caused neuronal oxidation and dopaminergic neuron loss; acrylamide induced demyelination; taxol, neomycin, TCDD and retinoic acid induced neuronal apoptosis.

DISCUSSION

Effects of drug treatment on different neurons can easily be visually assessed and quantified in intact animals. These results support the use of zebrafish as a predictive model for assessing neurotoxicity.

Structural and kinetic analysis of caspase-3 reveals role for s5 binding site in substrate recognition

The molecular basis for the substrate specificity of human caspase-3 has been investigated using peptide analog inhibitors and substrates that vary at the P2, P3, and P5 positions. Crystal structures were determined of caspase-3 complexes with the substrate analogs at resolutions of 1.7 A to 2.3 A. Differences in the interactions of caspase-3 with the analogs are consistent with the Ki values of 1.3 nM, 6.5 nM, and 12.4 nM for Ac-DEVD-Cho, Ac-VDVAD-Cho and Ac-DMQD-Cho, respectively, and relative kcat/Km values of 100%, 37% and 17% for the corresponding peptide substrates. The bound peptide analogs show very similar interactions for the main-chain atoms and the conserved P1 Asp and P4 Asp, while interactions vary for P2 and P3. P2 lies in a hydrophobic S2 groove, consistent with the weaker inhibition of Ac-DMQD-Cho with polar P2 Gln. S3 is a surface hydrophilic site with favorable polar interactions with P3 Glu in Ac-DEVD-Cho. Ac-DMQD-Cho and Ac-VDVAD-Cho have hydrophobic P3 residues that are not optimal in the polar S3 site, consistent with their weaker inhibition. A hydrophobic S5 site was identified for caspase-3, where the side-chains of Phe250 and Phe252 interact with P5 Val of Ac-VDVAD-Cho, and enclose the substrate-binding site by conformational change. The kinetic importance of hydrophobic P5 residues was confirmed by more efficient hydrolysis of caspase-3 substrates Ac-VDVAD-pNA and Ac-LDVAD-pNA compared with Ac-DVAD-pNA. In contrast, caspase-7 showed less efficient hydrolysis of the substrates with P5 Val or Leu compared with Ac-DVAD-pNA. Caspase-3 and caspase-2 share similar hydrophobic S5 sites, while caspases 1, 7, 8 and 9 do not have structurally equivalent hydrophobic residues; these caspases are likely to differ in their selectivity for the P5 position of substrates. The distinct selectivity for P5 will help define the particular substrates and signaling pathways associated with each caspase.

Expression of an anti apoptotic recombinant short peptide in mammalian cells

Understanding the mechanisms of the apoptotic and anti apoptotic processes may lead to a better way to control these cascades. Here we demonstrated for the first time the feasibility to express a short functional peptide in mammalian cells that abrogates the apoptosis cascade through interference with the proteolytic activity of the initiator caspase 9 and the executing caspase 3 enzymes. The expression of a short peptide that includes the pseudo-substrate motif of the apoptosis inhibitor protein P35 (Asp-Gln-Met-Asp) leads to the abrogation of cell death induced through either the mitochondrial or the death receptors pathways. Short open reading frames have been detected in several mammalian mRNAs, primarily upstream of the main long reading frame (uORFs), however, direct evidence for de-novo peptides translation has not been provided. Utilizing biochemical and imaging techniques we demonstrate here that the functional recombinant peptide was localized to the cytpoplasmic fraction of the cell. In conclusion, this work demonstrates that ribosomes recognize short ORFs to translate stable short recombinant peptides in mammalian cells. Expression of these intracellular peptides results in the knock down of apoptotic processes to generate apoptosis resistant stable cells.

The use of flow cytometric methods in acute and long-term in vitro testing

One principal demand for in vitro screening for toxic effects is the ease of performance and the high throughput of test methods. Flow cytometry offers the possibility to study several parameters simultaneously, e.g. cell cycle modulation, mode of cell death, activity of mitochondria. Aim of the present study was to assess the suitability of flow cytometry for the determination of cytotoxicity of test chemicals. Six chemicals chosen from the MEIC list (acetaminophen, isoniazid, paraquat, malathion, digoxin and 2,4-dichlorophenoxy acetic acid) were tested in HepG2, AAH-1, YAC-1 cells and human lymphocytes. Chemicals were applied for 24, 48 h or 28 days. The phases of the cell cycle were determined and the induction of apoptosis and necrosis was demonstrated by annexin binding, analysis of mitochondrial membrane potential and DNA strand breaks. The results of the present study show that flow cytometric methods are well suited to screen for the cytotoxicity of chemicals, both in adherent cells and cells grown in suspension.

Regulation of Bcl-2 family proteins, neurotrophic factors, and APP processing in the neurorescue activity of propargylamine

The anti-Parkinson drug, rasagiline (N-propargyl-(1R)-aminoindan) promotes neuronal survival, via neuroprotective activity related to its propargyl moiety (propargylamine). We have investigated the neurorescue effects of propargylamine, in a progressive neuronal death model, induced by long-term serum deprivation in human SH-SY5Y neuroblastoma cells. Propargylamine (0.1-10 microM) dose-dependently reduced the levels of the early apoptosis-associated phosphorylated protein, H2A-X (ser 139), as well as decreased the cleavage of caspase-3 and its substrate poly-ADP ribose polymerase (PARP). In addition, the compound markedly reversed the apoptotic effects induced by long-term serum withdrawal, including down-regulation of the antiapoptotic protein, Bcl-2, as well as up-regulation of the proapoptotic proteins, Bax, Bad, and Bim. Real-time RT-PCR demonstrated that propargylamine elevated gene expression levels of Bcl-2, and the neurotrophic factors glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) and reduced Bax gene expression. Serum deprivation increased mRNA and protein levels of holo-amyloid precursor protein (APP), which was markedly decreased by propargylamine. This was accompanied by inducing the release of the nonamyloidogenic alpha-secretase form of soluble APP (sAPPalpha) into the medium. Similar effects on cell survival and APP regulation/processing were demonstrated for rasagiline. These results indicate that both rasagiline and propargylamine possess neurorescue activity, associated with regulation of Bcl-2 family proteins, neurotrophic factors, and APP metabolism.