Cannabinoid receptor agonist WIN55,212-2 and fatty acid amide hydrolase inhibitor URB597 may protect against cognitive impairment in rats of chronic cerebral hypoperfusion via PI3K/AKT signaling

Anxiogenic doses of rapamycin prevent URB597-induced anti-stress effects in socially defeated mice

Repeated exposure to psychosocial stress modulates the endocannabinoid system, particularly anandamide (AEA) signaling in brain regions associated with emotional distress. The mTOR protein regulates various neuroplastic processes in the brain disrupted by stress, including adult hippocampal neurogenesis. This kinase has been implicated in multiple effects of cannabinoid drugs and the anti-stress behavioral effects of psychoactive drugs. Therefore, our hypothesis is that enhancing AEA signaling via pharmacological inhibition of the fatty acid amide hydrolase (FAAH) enzyme induces an anti-stress behavioral effect through an mTOR-dependent mechanism. To test this hypothesis, male C57Bl6 mice were exposed to social defeat stress (SDS) for 7 days and received daily treatment with either vehicle or different doses of the FAAH inhibitor, URB597 (0.1; 0.3; 1 mg/Kg), alone or combined with rapamycin. The results suggested that URB597 induced an inverted U-shaped dose-response curve in mice subjected to SDS (with the intermediate dose of 0.3 mg/kg being anxiolytic, and the higher tested dose of 1 mg/Kg being anxiogenic). In a second independent experiment, rapamycin treatment induced an anxiogenic-like response in control mice. However, in the presence of rapamycin, the anxiolytic dose of URB597 treatment failed to reduce stress-induced anxiety behaviors in mice. SDS exposure altered the hippocampal expression of the mTOR scaffold protein Raptor. Furthermore, the anxiogenic dose of URB597 decreased the absolute number of migrating doublecortin (DCX)-positive cells in the dentate gyrus, suggesting an anti-anxiety effect independent of newly generated/immature neurons. Therefore, our results indicate that in mice exposed to repeated psychosocial stress, URB597 fails to counteract the anxiogenic-like response induced by the pharmacological dampening of mTOR signaling.

ChemR23 activation attenuates cognitive impairment in chronic cerebral hypoperfusion by inhibiting NLRP3 inflammasome-induced neuronal pyroptosis

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.

URB597 exerts neuroprotective effects against transient brain ischemia injury in mice by regulating autophagic flux and necroptosis

Ischemic stroke is a leading cause of death and disability, and medical treatments for ischemic stroke are very limited. URB597 is a potent and selective inhibitor of fatty acid amide hydrolase (FAAH). However, the effect of URB597 on ischemic stroke and the underlying molecular mechanisms remain little known. In this study, focal cerebral ischemia was induced by transient middle cerebral artery occlusion in mice. Our results showed that URB597 dose-dependently improved neurological function and reduced brain infarct volume and brain edema 24 h after brain ischemia. The most effective dose was 1 mg/kg and the therapeutic time window was within 3 h after ischemic stroke. To further investigate the underlying mechanism, necroptosis and autophagy flux were detected by Western blot and/or immunofluorescence staining with or without chloroquine, an autophagic flux inhibitor. Our results showed that URB597 promoted autophagic flux and reduced neuronal necroptosis after brain ischemia and these effects could be abolished by chloroquine. In addition, we found that peroxisome proliferator-activated receptor α (PPARα) antagonist GW6471 partly abolished the effect of URB597 against brain ischemia and URB597 upregulated the expressions of PPARα. In conclusion, URB597 exerts a neuroprotective effect in a dose- and time-dependent manner, and this effect may be related to its restoration of autophagic flux and inhibition of neuronal necroptosis. PPARα is involved in the neuroprotective effect of URB597. This study provides novel evidence that URB597 may be a promising agent for the clinical treatment of ischemic stroke.

VCAM1 Drives Vascular Inflammation Leading to Continuous Cortical Neuronal Loss Following Chronic Cerebral Hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is associated with neuronal loss and blood-brain barrier (BBB) impairment in vascular dementia (VaD). However, the relationship and the molecular mechanisms between BBB dysfunction and neuronal loss remain elusive.

OBJECTIVE

We explored the reasons for neuron loss following CCH.

METHODS

Using permanent bilateral common carotid artery occlusion (2VO) rat model, we observed the pathological changes of cortical neurons and BBB in the sham group as well as rats 3d, 7d, 14d and 28d post 2VO. In order to further explore the factors influencing neuron loss following CCH with regard to cortical blood vessels, we extracted cortical brain microvessels at five time points for transcriptome sequencing. Finally, integrin receptor a4β1 (VLA-4) inhibitor was injected into the tail vein, and cortical neuron loss was detected again.

RESULTS

We found that cortical neuron loss following CCH is a continuous process, but damage to the BBB is acute and transient. Results of cortical microvessel transcriptome analysis showed that biological processes related to vascular inflammation mainly occurred in the chronic phase. Meanwhile, cell adhesion molecules, cytokine-cytokine receptor interaction were significantly changed at this phase. Among them, the adhesion molecule VCAM1 plays an important role. Using VLA-4 inhibitor to block VCAM1-VLA-4 interaction, cortical neuron damage was ameliorated at 14d post 2VO.

CONCLUSION

Injury of the BBB may not be the main reason for persistent loss of cortical neurons following CCH. The continuous inflammatory response within blood vessels maybe an important factor in the continuous loss of cortical neurons following CCH.

Fatty Acid Amide Hydrolase (FAAH) Inhibition Plays a Key Role in Counteracting Acute Lung Injury

Acute lung injury (ALI) is a group of lung illnesses characterized by severe inflammation, with no treatment. The fatty acid amide hydrolase (FAAH) enzyme is an integral membrane protein responsible for the hydrolysis of the main endocannabinoids, such as anandamide (AEA). In pre-clinical pain and inflammation models, increasing the endogenous levels of AEA and other bioactive fatty acid amides (FAAs) via genetic deletion or the pharmacological inhibition of FAAH produces many analgesic benefits in several different experimental models. To date, nobody has investigated the role of FAAH inhibition on an ALI mouse model. Mice were subjected to a carrageenan injection and treated orally 1 h after with the FAAH inhibitor URB878 dissolved in a vehicle consisting of 10% PEG-400, 10% Tween-80 and 80% saline at different doses: The inhibition of FAAH activity was able to counteract not only the CAR-induced histological alteration, but also the cascade of related inflammatory events. URB878 clears the way for further studies based on FAAH inhibition in acute lung pathologies.

The Cannabinoid Receptor Agonist, WIN-55212-2, Suppresses the Activation of Proinflammatory Genes Induced by Interleukin 1 Beta in Human Astrocytes

Background: Alterations of astrocyte function play a crucial role in neuroinflammatory diseases due to either the loss of their neuroprotective role or the gain of their toxic inflammatory properties. Accumulating evidence highlights that cannabinoids and cannabinoid receptor agonists, such as WIN55,212-2 (WIN), reduce inflammation in cellular and animal models. Thus, the endocannabinoid system has become an attractive target to attenuate chronic inflammation in neurodegenerative diseases. However, the mechanism of action of WIN in astrocytes remains poorly understood. Objective: We studied the immunosuppressive property of WIN by examining gene expression patterns that were modulated by WIN in reactive astrocytes. Materials and Methods: Transcriptomic analysis by RNA-seq was carried out using primary human astrocyte cultures stimulated by the proinflammatory cytokine interleukin 1 beta (IL1β) in the presence or absence of WIN. Real-time quantitative polymerase chain reaction analysis was conducted on selected transcripts to characterize the dose-response effects of WIN, and to test the effect of selective antagonists of cannabinoid receptor 1 (CB1) and peroxisome proliferator-activated receptors (PPAR). Results: Transcriptomic analysis showed that the IL1β-induced inflammatory response is robustly inhibited by WIN pretreatment. WIN treatment alone also induced substantial gene expression changes. Pathway analysis revealed that the anti-inflammatory properties of WIN were linked to the regulation of kinase pathways and gene targets of neuroprotective transcription factors, including PPAR and SMAD (mothers against decapentaplegic homolog). The inhibitory effect of WIN was dose-dependent, but it was not affected by selective antagonists of CB1 or PPAR. Conclusions: This study suggests that targeting the endocannabinoid system may be a promising strategy to disrupt inflammatory pathways in reactive astrocytes. The anti-inflammatory activity of WIN is independent of CB1, suggesting that alternative receptors mediate the effects of WIN. These results provide mechanistic insights into the anti-inflammatory activity of WIN and highlight that astrocytes are a potential therapeutic target to ameliorate neuroinflammation in the brain.

The interplay between oxidative stress and autophagy: focus on the development of neurological diseases

Regarding the epidemiological studies, neurological dysfunctions caused by cerebral ischemia or neurodegenerative diseases (NDDs) have been considered a pointed matter. Mount-up shreds of evidence support that both autophagy and reactive oxygen species (ROS) are involved in the commencement and progression of neurological diseases. Remarkably, oxidative stress prompted by an increase of ROS threatens cerebral integrity and improves the severity of other pathogenic agents such as mitochondrial damage in neuronal disturbances. Autophagy is anticipated as a cellular defending mode to combat cytotoxic substances and damage. The recent document proposes that the interrelation of autophagy and ROS creates a crucial function in controlling neuronal homeostasis. This review aims to overview the cross-talk among autophagy and oxidative stress and its molecular mechanisms in various neurological diseases to prepare new perceptions into a new treatment for neurological disorders. Furthermore, natural/synthetic agents entailed in modulation/regulation of this ambitious cross-talk are described.

Cannabidiol reverses memory impairments and activates components of the Akt/GSK3β pathway in an experimental model of estrogen depletion

Clinical and preclinical evidence has indicated that estrogen depletion leads to memory impairments and increases the susceptibility to neural damage. Here, we have sought to investigate the effects of Cannabidiol (CBD) a non-psychotomimetic compound from Cannabis sativa, on memory deficits induced by estrogen depletion in rats, and its underlying mechanisms. Adult rats were subjected to bilateral ovariectomy, an established estrogen depletion model in rodents, or sham surgery and allowed to recover for three weeks. After that, they received daily injections of CBD (10 mg/kg) for fourteen days. Rats were tested in the inhibitory avoidance task, a type of emotionally-motivated memory. After behavioral testing they were euthanized, and their hippocampi were isolated for analysis of components of the Akt/GSK3β survival pathway and the antiapoptotic protein Bcl2. Results revealed that ovariectomy impaired avoidance memory, and CBD was able to completely reverse estrogen depletion-induced memory impairment. Ovariectomy also reduced Akt/GSK3β pathway's activation by decreasing the phosphorylation levels of Akt and GSK3β and Bcl2 levels, which were ameliorated by CBD. The present results indicate that CBD leads to a functional recovery accompanied by the Akt/GSK3β survival pathway's activation, supporting its potential as a treatment for estrogen decline-induced deterioration of neural functioning and maintenance.

Role of PI3K/Akt axis in mitigating hippocampal ischemia-reperfusion injury via CB1 receptor stimulation by paracetamol and FAAH inhibitor in rat

AIMS

Acetaminophen or paracetamol (PAR), the recommended antipyretic in COVID-19 and clinically used to alleviate stroke-associated hyperthermia interestingly activates cannabinoid receptor (CB1) through its AM404 metabolite, however, to date, no study reports the in vivo activation of PAR/AM404/CB1 axis in stroke. The current study deciphers the neuroprotective effect of PAR in cerebral ischemia/reperfusion (IR) rat model and unmasks its link with AM404/CB1/PI3K/Akt axis.

MATERIALS AND METHODS

Animals were allocated into 5 groups: (I) sham-operated (SO), (II) IR, (III) IR + PAR (100 mg/kg), (IV) IR + PAR (100 mg/kg) + URB597; anandamide degradation inhibitor (0.3 mg/kg) and (V) IR + PAR (100 mg/kg) + AM4113; CB1 Blocker (5 mg/kg). All drugs were intraperitoneally administered at the inception of the reperfusion period.

KEY FINDINGS

PAR administration alleviated the cognitive impairment in the Morris Water Maze as well as hippocampal histopathological and immunohistochemical examination of GFAP. The PAR signaling was associated with elevation of anandamide level, CB1 receptor expression and survival proteins as p^S473-Akt. P^{(tyr202/thr204)}-ERK1/2 and p^S9-GSK3β. Simultaneously, PAR increased hippocampal BDNF and ß-arrestin1 levels and decreased glutamate level. PAR restores the deranged redox milieu induced by IR Injury, by reducing lipid peroxides, myeloperoxidase activity and NF-κB and increasing NPSH, total antioxidant capacity, nitric oxide and Nrf2 levels. The pre-administration of AM4113 reversed PAR effects, while URB597 potentiated them.

SIGNIFICANCE

PAR poses a significant neuroprotective effect which may be mediated, at least in part, via activation of anandamide/CB1/PI3K/Akt pathway in the IR rat model.

The role of fatty acid amide hydrolase enzyme inhibitors in Alzheimer's disease

Fatty acid amide hydrolase (FAAH) is a prominent enzyme of the endocannabinoid system that degrades endogenous cannabinoid anandamide and oleamide. These lipid amides are involved in reducing neuroinflammation, pain and regulation of other neurological-related activities including feeding behaviours, sleep patterns, body temperature, memory processes and locomotory activity. Many of these activities are affected in most neurological disorders. Increased levels of brain FAAH expressions are speculated to correlate with decreased levels of lipid amides and increased AD-related symptoms. Thus, inhibition of FAAH shows promising potential in amelioration of symptoms associated with Alzheimer's disease (AD). The review aims at establishing the detrimental role of increased FAAH expression in AD and highlights the translational potential and therapeutic application of FAAH inhibitors in AD.

Neuroprotective effects of minocycline and KML29, a potent inhibitor of monoacylglycerol lipase, in an experimental stroke model: a small-animal positron emission tomography study

Hypoxia caused by ischemia induces acidosis and neuroexcitotoxicity, resulting in neuronal death in the central nervous system (CNS). Monoacylglycerol lipase (MAGL) is a modulator of 2-arachidonoylglycerol (2-AG), which is involved in retrograde inhibition of glutamate release in the endocannabinoid system. In the present study, we used positron emission tomography (PET) to monitor MAGL-positive neurons and neuroinflammation in the brains of ischemic rats. Additionally, we performed PET imaging to evaluate the neuroprotective effects of an MAGL inhibitor in an ischemic injury model.

Methods: Ischemic-injury rat models were induced by intraluminal right middle cerebral artery occlusion (MCAO). PET studies of the brains of the ischemic rats were performed at several experimental time points (pre-occlusion, days 2, 4, and 7 after the MCAO surgery) using [¹¹C]SAR127303 for MAGL and [¹⁸F]FEBMP for 18 kDa translocator protein (TSPO, a hall-mark of neuroinflammation). Medication using minocycline (a well-known neuroprotective agent) or KML29 (a potent MAGL inhibitor) was given immediately after the MCAO surgery and then daily over the subsequent three days.

Results: PET imaging of the ischemic rats using [¹¹C]SAR127303 showed an acute decline of radioactive accumulation in the ipsilateral side at two days after MCAO surgery (ratio of the area under the curve between the ipsilateral and contralateral sides: 0.49 ± 0.04 in the cortex and 0.73 ± 0.02 in the striatum). PET imaging with [¹⁸F]FEBMP, however, showed a moderate increase in accumulation of radioactivity in the ipsilateral hemisphere on day 2 (1.36 ± 0.11), and further increases on day 4 (1.72 ± 0.15) and day 7 (1.99 ± 0.06). Treatment with minocycline or KML29 eased the decline in radioactive accumulation of [¹¹C]SAR127303 for MAGL (minocycline-treated group: 0.82 ± 0.06 in the cortex and 0.81 ± 0.05 in the striatum; KML29-treated group: 0.72 ± 0.07 in the cortex and 0.88 ± 0.04 in the striatum) and increased uptake of [¹⁸F]FEBMP for TSPO (minocycline-treated group: 1.52 ± 0.21 in the cortex and 1.56 ± 0.11 in the striatum; KML29-treated group: 1.63 ± 0.09 in the cortex and 1.50 ± 0.17 in the striatum). In MCAO rats, minocycline treatment showed a neuroprotective effect in the sensorimotor cortex suffering from severe hypoxic injury, whereas KML29 treatment saved neurons in the striatum, including bundles of myelinated axons.

Conclusions: PET imaging allowed visualization of the different neuroprotective effects of minocycline and KML29, and indicated that combination pharmacotherapy using these drugs may be an effective therapy in acute ischemia.

The role of endocannabinoid pathway in the neuropathology of Alzheimer's disease: Can the inhibitors of MAGL and FAAH prove to be potential therapeutic targets against the cognitive impairment associated with Alzheimer's disease?

Alzheimer's disease is a neurodegenerative disease characterized by progressive decline of cognitive function in combination with neuronal death. Current approved treatment target single dysregulated pathway instead of multiple mechanism, resulting in lack of efficacy in slowing down disease progression. The proclivity of endocannabinoid system to exert neuroprotective action and mitigate symptoms of neurodegeneration condition has received substantial interest. Growing evidence suggest the endocannabinoids (eCB) system, viz. anadamide (AEA) and arachidonoyl glycerol (2-AG), as potential therapeutic targets with the ability to modify Alzheimer's pathology by targeting the inflammatory, neurodegenerative and cognitive aspects of the disease. In order to modulate endocannabinoid system, number of agents have been reported amongst which are inhibitors of the monoacylglycerol (MAGL) and fatty acid amide hydrolase (FAAH), the enzymes that hydrolyses 2-AG and AEA respectively. However, little is known regarding the exact mechanistic signalling and their effects on pathophysiology and cognitive decline associated with Alzheimer's disease. Both MAGL and FAAH inhibitors possess fascinating properties that may offer a multi-faceted approach for the treatment of Alzheimer's disease such as potential to protect neurons from deleterious effect of amyloid-β, reducing phosphorylation of tau, reducing amyloid-β induced oxidative stress, stimulating neurotrophin to support brain intrinsic repair mechanism etc. Based on empirical evidence, MAGL and FAAH inhibitors might have potential for therapeutic efficacy against cognitive impairment associated with Alzheimer's disease. The aim of this review is to summarize the experimental studies demonstrating the polyvalent properties of MAGL or FAAH inhibitor compounds for the treatment of Alzheimer's disease, and also effect of these on learning and types of memories, which together encourage to study these compounds over other therapeutics targets. Further research in this direction would enhance the molecular mechanisms and development of applicable interventions for the treatment of Alzheimer's disease, which nevertheless stay as the primary unmet need.

Low-Frequency Stimulation Prevents Kindling-Induced Impairment through the Activation of the Endocannabinoid System

Background

Cannabinoid system affects memory and has anticonvulsant effects in epileptic models. In the current study, the role of cannabinoid 1 (CB1) receptors was investigated in amelioration of the effects of low-frequency stimulation (LFS) on learning and memory impairments in kindled rats.

Methods

Electrical stimulation of the hippocampal CA1 area was employed to kindle the animals. LFS was applied to the CA1 area in four trials following the last kindling stimulation. One group of animals received intraperitoneal injection of AM251 (0.1 μg/rat), a CB1 receptor antagonist, before the LFS application. Similarly, CB1 agonist WIN55-212-2 (WIN) was administrated to another group prior to LFS. The Morris water maze (MWM) and the novel object recognition (NOR) tests were executed 48 h after the last kindling stimulation to assess learning and memory.

Results

Applying LFS in the kindled+LFS group restored learning and memory impairments in the kindled rats. There was a significant difference between the kindled and the kindled+LFS groups in learning and memory. The application of AM251 reduced the LFS effects significantly. Adversely, WIN acted similarly to LFS and alleviated learning and memory deficits in the kindled+WIN group. In addition, WIN did not counteract the LFS enhancing effects in the KLFS+WIN group.

Conclusions

Improving effects of LFS on learning and memory impairments are mediated through the activation of the endocannabinoid (ECB) system.

Neuroprotective Effects of VEGF-A Nanofiber Membrane and FAAH Inhibitor URB597 Against Oxygen-Glucose Deprivation-Induced Ischemic Neuronal Injury

INTRODUCTION

Brain ischemia is a common neurological disorder worldwide that activates a cascade of pathophysiological events involving decreases in oxygen and glucose levels. Despite substantial efforts to explore its pathogenesis, the management of ischemic neuronal injury remains an enormous challenge. Accumulating evidence suggests that VEGF modified nanofiber (NF) materials and the fatty-acid amide hydrolase (FAAH) inhibitor URB597 exert an influence on alleviating ischemic brain damage. We aimed to further investigate their effects on primary hippocampal neurons, as well as the underlying mechanisms following oxygen-glucose deprivation (OGD).

METHODS

Different layers of VEGF-A loaded polycaprolactone (PCL) nanofibrous membranes were first synthesized by using layer-by-layer (LBL) self-assembly of electrospinning methods. The physicochemical and biological properties of VEGF-A NF membranes, and their morphology, hydrophilicity, and controlled-release of VEGF-A were then estimated. Furthermore, the effects of VEGF-A NF and URB597 on OGD-induced mitochondrial oxidative stress, inflammatory responses, neuronal apoptosis, and endocannabinoid signaling components were assessed.

RESULTS

The VEGF-A NF membrane and URB597 can not only promote hippocampal neuron adhesion and viability following OGD but also exhibited antioxidant/anti-inflammatory and mitochondrial membrane potential protection. The VEGF-A NF membrane and URB597 also inhibited OGD-induced cellular apoptosis through activating CB1R signaling. These results indicate that VEGF-A could be controlled-released by LBL self-assembled NF membranes.

DISCUSSION

The VEGF-A NF membrane and URB597 displayed positive synergistic neuroprotective effects through the inhibition of mitochondrial oxidative stress and activation of CB1R/PI3K/AKT/BDNF signaling, suggesting that a VEGF-A loaded NF membrane and the FAAH inhibitor URB597 could be of therapeutic value in ischemic cerebrovascular diseases.

Pharmacological Treatment of Vascular Dementia: A Molecular Mechanism Perspective

Vascular dementia (VaD) is a neurodegenerative disease, with cognitive dysfunction attributable to cerebrovascular factors. At present, it is the second most frequently occurring type of dementia in older adults (after Alzheimer's disease). The underlying etiology of VaD has not been completely elucidated, which limits its management. Currently, there are no approved standard treatments for VaD. The drugs used in VaD are only suitable for symptomatic treatment and cannot prevent or reduce the occurrence and progression of VaD. This review summarizes the current status of pharmacological treatment for VaD, from the perspective of the molecular mechanisms specified in various pathogenic hypotheses, including oxidative stress, the central cholinergic system, neuroinflammation, neuronal apoptosis, and synaptic plasticity. As VaD is a chronic cerebrovascular disease with multifactorial etiology, combined therapy, targeting multiple pathophysiological factors, may be the future trend in VaD.

Preservation of spatial memory and neuroprotection by the fatty acid amide hydrolase inhibitor URB597 in a rat model of vascular dementia

Background

Chronic cerebral hypoperfusion (CCH) is a major risk factor for vascular dementia (VaD). There are currently no broadly effective prevention or treatment strategies for VaD, but recent studies have reported promising results following vascular bypass surgery and pharmacomodulation of the brain endocannabinoid system (ECS). In this study, early effects of encephalomyosynangiosis (EMS) bypass surgery and augmented endocannabinoid signaling on CCH-induced cognitive dysfunction and neuronal damage were investigated.

Methods

An animal model of VaD was established by bilateral common carotid artery occlusion (BCCAO). Cannabinoid signaling was upregulated by treatment with the fatty acid amide hydrolase inhibitor URB597 (URB). Spatial learning and memory, cerebral blood flow (CBF), revascularization, brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling, and apoptosis were compared among Sham, BCCAO, BCCAO + EMS, BCCAO + URB, and BCCAO + URB + EMS groups. Spatial learning and memory were evaluated using the Morris water maze (MWM). The CBF in cortex and hippocampus was evaluated by 3-dimensional arterial spin labeling. The neovascularization was visualized by CD34 immunofluorescence staining, and BDNF-TrkB signaling protein expression levels were assessed by Western blotting.

Results

Treatment with URB597 but not EMS alone reversed the spatial learning and memory deficits induced by BCCAO. Neovascularization was enhanced after EMS surgery but not by URB597. Alternatively, there were no significant differences in CBF among treatment groups. Expression levels of BDNF and TrkB were significantly reduced by CCH compared to Sham treatment, and downregulation of both proteins was reversed by URB597 treatment but not EMS. BCCAO enhanced neuronal apoptosis, which was also reversed by URB597.

Conclusions

Augmentation of endogenous cannabinoid signaling but not EMS protects against CCH-induced neurodegeneration and preserves spatial learning and memory, possibly by activating BDNF-TrkB signaling.

Effect of acute and subchronic administration of (R)-WIN55,212-2 induced neuroprotection and anti inflammatory actions in rat retina: CB1 and CB2 receptor involvement

Cannabinoids have been shown to protect the retina from ischemic/excitotoxic insults. The aim of the present study was to investigate the neuroprotective and anti-inflammatory properties of the synthetic cannabinoid (R)-WIN55,212-2 (CB1/CB2 receptor agonist) when administered acutely or subchronically in control and AMPA treated retinas. Sprague-Dawley rats were intravitreally administered (acutely) with vehicle or AMPA, in the absence or presence of (R)-WIN55,212-2 (10^-7-10^-4M) alone or in combination with AM251 [CB1 receptor antagonist/inverse agonist,10^-4M] and AM630 (CB2 receptor antagonist,10^-4M). In addition, AMPA was co-administered with the racemic (R,S)-WIN55,212 (10^-4Μ). (R)-WIN55,212-2 was also administered subchronically (25,100 μg/kg,i.p.,4d) in control and AMPA treated rats. Immunohistochemical studies were performed using antibodies against the CB1R, and retinal markers for retinal neurons (brain nitric oxide synthetase, bNOS) and microglia (ionized calcium binding adaptor molecule 1, Iba1). ELISA assay was employed to assess TNFα levels in AMPA treated retinas. Intravitreal administration of (R)-WIN55,212-2 reversed the AMPA induced loss of bNOS expressing amacrine cells, an effect that was blocked by both AM251 and AM630. (R,S)WIN55,212 had no effect. (R)-WIN55,212-2 also reduced a) the AMPA induced activation of microglia, by activating CB2 receptors that were shown to be colocalized with Iba1⁺ reactive microglial cells, and b) TNFα levels in retina. (R)-WIN55,212-2 administered subchronically led to the downregulation of CB1 receptors at the high dose of 100 μg/kg(i.p.), and to the attenuation of the WIN55,212-2 induced neuroprotection of amacrine cells. At the same dose, (R)-WIN55,212-2 did not attenuate the AMPA induced increase in the number of reactive microglia cells, suggesting CB2 receptor downregulation under subchronic conditions. This study provides new findings regarding the role of CB1 and CB2 receptor activation by the synthetic cannabinoid (R)-WIN55,212-2, administered acutely or sub-chronically, on neuron viability and microglia activation in healthy and diseased retina.

Inflammasome and Mitophagy Connection in Health and Disease

The inflammasome is a large intracellular protein complex that activates inflammatory caspase-1 and induces the maturation of interleukin (IL)-1β and IL-18. Mitophagy plays an essential role in the maintenance of mitochondrial homeostasis during stress. Previous studies have indicated compelling evidence of the crosstalk between inflammasome and mitophagy. Mitophagy regulation of the inflammasome, or vice versa, is crucial for various biological functions, such as controlling inflammation and metabolism, immune and anti-tumor responses, and pyroptotic cell death. Uncontrolled regulation of the inflammasome often results in pathological inflammation and pyroptosis, and causes a variety of human diseases, including metabolic and inflammatory diseases, infection, and cancer. Here, we discuss how improved understanding of the interactions between inflammasome and mitophagy can lead to novel therapies against various disease pathologies, and how the inflammasome-mitophagy connection is currently being targeted pharmacologically by diverse agents and small molecules. A deeper understanding of the inflammasome-mitophagy connection will provide new insights into human health and disease through the balance between mitochondrial clearance and pathology.

Effect of (m)RVD-hemopressin against Aβ1-42-induced apoptosis and inhibition of neurite outgrowth in SH-SY5Y cells

Alzheimer's disease (AD) is a serious neurodegenerative disease. Senile plaques (SPs) in the extracellular space and neurofibrillary tangles (NFTs) in the intracellular areas of the brain are two typical features of AD. SPs and NFTs are composed of amyloid-β (Aβ) aggregates and hyperphosphorylated Tau, respectively. (m)RVD-hemopressin (RVD), which is derived from mouse brain peptide, binds to the cannabinoid 1 receptor (CB1R) as an agonist. Our previous study indicated that RVD reversed Aβ1-42-induced memory impairment in mice. Here, we investigated the underlying molecular mechanism of RVD on Aβ1-42-induced neurotoxicity in retinoic acid-differentiated human neuroblastoma SH-SY5Y cells. Cell viability and neurite outgrowth were investigated by live cell imaging and analysis instrument. We found that RVD reversed Aβ1-42-induced Tau phosphorylation, apoptosis and suppression of neurite outgrowth and the synapse-associated protein postsynaptic density protein 95 (PSD-95) by inhibiting the activity of protein kinase A (PKA) and glycogen synthase kinase 3β (GSK-3β). Combined treatment with AM251 (a CB1R antagonist) blocked the effects of RVD. In conclusion, RVD may be a potential therapeutic agent for the treatment of cognitive dysfunctions, such as Alzheimer's disease.

Effect of (m)VD-hemopressin against Aβ1-42-induced oxidative stress and apoptosis in mouse hippocampal neurons

Alzheimer's disease (AD) is a serious neurodegenerative disease. Senile plaques (SPs) composed of amyloid-β (Aβ) are typical features of AD. Aβ plays a key role in the disease and has the ability to induce other pathological characteristics of AD, including oxidative stress injury. (m)VD-hemopressin (VD), a peptide derived from mouse brain extracts, can bind cannabinoid 1 receptor (CB1R) as an agonist. Our previous report indicated that VD reverses memory impairment induced by Aβ1-42 in mice. This study aimed to clarify the mechanism by which VD protects hippocampal neurons against Aβ1-42-induced impairment. Our results showed that VD inhibited oxidative stress injury induced by Aβ1-42, as demonstrated by the VD-induced reversal of the upregulation of reactive oxygen species (ROS) and the intracellular lipid peroxidation product malondialdehyde (MDA) and the downregulation of the activities of the antioxidative enzymes catalase (CAT) and glutathione peroxidase (GSH-PX) in mouse hippocampal neurons. We also found that VD restored the decrease in cell growth and viability induced by Aβ1-42 and reversed Aβ1-42-induced apoptosis mediated by the apoptosis-associated proteins Bcl-2 and Bax. However, cotreatment with AM251 (an antagonist of CB1R) blocked the effects of VD. In brief, this study suggested that through CB1R, VD reversed the impairment of cell growth and viability, oxidative stress injury and apoptosis induced by Aβ1-42. Therefore, VD may be a promising agent for the treatment of diseases that involve oxidative stress injury and apoptosis induced by Aβ1-42, such as AD.

The cannabinoid agonist WIN-2 affects acquisition but not consolidation of a spatial information in training and retraining processes: Relation with transcriptional regulation of the endocannabinoid system?

The endocannabinoid system is capable of modulating multiple physiological brain functions including learning and memory. Moreover, there is evidence that the processes of acquisition and consolidation have distinct biological basis. We used the cannabinoid agonist WIN 55,212-2 (WIN-2) to investigate whether chronic CB1 activation affects acquisition and consolidation differently by evaluating gene expression in the hippocampus (HIP) and prefrontal cortex (PFC). Swiss mice were treated with WIN-2 (2 mg/kg) and submitted to the Morris water maze to evaluate different aspects of memory. We observed short-term memory impairment in acquisition of the spatial task while consolidation remained unchanged. In the PFC, animals that received WIN-2 prior to the task exhibited increased expression of the 2-AG synthesis enzyme diacylglycerol lipase and decreased levels of the degradation enzyme monoacylglycerol lipase, while mice that were treated after the task for the evaluation of consolidation exhibited the opposite profile. With respect to genes related to AEA metabolism, no correlation between the molecular and behavioral data could be established. In this sense, the cognitive impairment in the acquisition promoted by WIN-2 treatment may be related to a possible increase in the concentration of 2-AG in the PFC. Overall, this study confirms the relevance of the endocannabinoid system in the modulation of cognitive processes. A better understanding of the mechanisms underlying endocannabinoids roles in cognition could provide guidance for the development of treatments to reduce the cognitive deficits caused by drug abuse.

URB597 protects against NLRP3 inflammasome activation by inhibiting autophagy dysfunction in a rat model of chronic cerebral hypoperfusion

Background

Previous studies reported that URB597 (URB) had therapeutic potential for treating chronic cerebral hypoperfusion (CCH)-induced neuroinflammation and autophagy dysfunction. However, the interaction mechanisms underlying the CCH-induced abnormal excessive autophagy and neuroinflammation remain unknown. In this study, we investigated the roles of impaired autophagy in nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing (NLRP) 3 inflammasome activation in the rat hippocampus and the underlying mechanisms under the condition of induced CCH as well as the effect of URB treatment.

Methods

The CCH rat model was established by bilateral common carotid artery occlusion (BCCAo), and rats were randomly divided into 11 groups as follows: (1) sham-operated, (2) BCCAo; (3) BCCAo+autophagy inhibitor 3-methyladenine (3-MA), (4) BCCAo+lysosome inhibitor chloroquine (CQ), (5) BCCAo+microglial activation inhibitor minocycline, (6) BCCAo+ROS scavenger N-acetylcysteine (NAC), (7) BCCAo+URB, (8) BCCAo+URB+3-MA, (9) BCCAo+URB+CQ, (10) BCCAo+URB+minocycline, (11) BCCAo+URB+NAC. The cell localizations of LC3, p62, LAMP1, TOM20 and NLRP3 were assessed by immunofluorescence staining. The levels of autophagy-related proteins (LC3, p62, LAMP1, BNIP3 and parkin), NLRP3 inflammasome-related proteins (NLRP3, CASP1 and IL-1β), microglial marker (OX-42) and proinflammatory cytokines (iNOS and COX-2) were evaluated by western blotting, and proinflammatory cytokines (IL-1β and TNF-a) were determined by ELISA. Reactive oxygen species (ROS) were assessed by dihydroethidium staining. The mitochondrial ultrastructural changes were examined by electron microscopy.

Results

CCH induced microglial overactivation and ROS accumulation, promoting the activation of the NLRP3 inflammasome and the release of IL-1β. Blocked autophagy and mitophagy flux enhanced the activation of the NLRP3-CASP1 inflammasome pathway. However, URB alleviated impaired autophagy and mitophagy by decreasing mitochondrial ROS and microglial overactivation as well as restoring lysosomal function, which would further inhibit the activation of the NLRP3-CASP1 inflammasome pathway.

Conclusion

These findings extended previous studies indicating the function of URB in the mitigation of chronic ischemic injury of the brain.

The Cannabinoid Receptor Agonist WIN55,212-2 Ameliorates Hippocampal Neuronal Damage After Chronic Cerebral Hypoperfusion Possibly Through Inhibiting Oxidative Stress and ASK1-p38 Signaling

Chronic cerebral hypoperfusion (CCH) is a major contributor to cognitive decline and degenerative processes leading to Alzheimer's disease, vascular dementia, and aging. However, the delicate mechanism of CCH-induced neuronal damage, and therefore proper treatment, remains unclear. WIN55,212-2 (WIN) is a nonselective cannabinoid receptor agonist that has been shown to have effects on hippocampal neuron survival. In this study, we investigated the potential roles of WIN, as well as its underlying mechanism in a rat CCH model of bilateral common carotid artery occlusion. Hippocampal morphological changes and mitochondrial ultrastructure were detected using hematoxylin and eosin staining and electron microscopy, respectively. Various biomarkers, such as reactive oxidative species (ROS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were used to assess the level of oxidative stress in the hippocampus. Furthermore, the expression levels of neuronal nuclei (NeuN), apoptosis signal-regulating kinase 1 (ASK1)-p38 signaling proteins, cleaved Caspase-9 and -3, and cytochrome-c (Cyt-C) were accessed by western blotting. CCH decreased the levels of NeuN, Cyt-C (mitochondrial), SOD, and CAT, and increased the levels of MDA, phosphorylated ASK1 and phosphorylated p38, cleaved Caspase-9 and -3, and Cyt-C (cytoplasm), which were reversed by WIN treatment. Chronic treatment with WIN also improved CCH-induced neuronal degeneration and mitochondrial fragmentation. These findings indicated that WIN may be a potential therapeutic agent for ischemic neuronal damage, involving a mechanism associated with the suppression of oxidative stress and ASK1-p38 signaling.

Protective effects of macamides from Lepidium meyenii Walp. against corticosterone-induced neurotoxicity in PC12 cells

Maca has attracted considerable attention owing to its neuroprotective effects in vitro and vivo. Macamides, a series of nonpolar and long-chain fatty acid N-benzylamides, are considered unique constituents in maca. This study investigated the protective effects of ethanol extracts of maca (EEM) and macamides on corticosterone-induced (CORT) neurotoxicity in rat pheochromocytoma (PC12) cells. CORT reduced cell viability and increased LDH release, intracellular ROS levels, and MMP decline rate, and induced mitochondrial apoptosis. However, pretreatment with EEM and macamides ameliorated CORT-induced neurotoxicity. EEM increased the cell viability and reduced the LDH release. M 18:1, M 18:2, and M 18:3 increased cell viability and reduced LDH release and intracellular ROS generation. M 18:2 and M 18:3 inhibited MMP reduction and reduced the Bax/Bcl-2 ratios. M 18:1 reduced the intracellular ROS without affecting other factors. Moreover, M 18:3 prevented CORT-induced mitochondrial apoptosis, restrained the expression levels of pro-apoptotic proteins, namely, Bax, cytochrome C, cleaved-caspase-3, and cleaved-PARP, and increased the expression levels of Bcl-2. In addition, M 18:3 increased Akt phosphorylation and the ability of M 18:3 to protect against CORT-induced cytotoxicity was remarkably reduced by LY294002, a PI3K phosphorylation inhibitor. M 18:3 also elevated the phosphorylation of CREB and activated the BDNF protein levels in CORT-induced PC12 cells. In conclusion, macamides, especially M 18:3, exert protective effects on CORT-induced PC12 cells. The cellular mechanism of M 18:3 against CORT-induced cytotoxicity may involve inhibition of mitochondrial apoptosis, and activation of Akt and CREB phosphorylation. Overall, macamides may potentially treat neuronal damage induced by CORT.

Neuroprotection of macamides is probably associated with inhibition of the mitochondrial apoptotic and the activation of the phosphorylation of Akt and CREB.

Pharmacological blockade of fatty acid amide hydrolase (FAAH) by URB597 improves memory and changes the phenotype of hippocampal microglia despite ethanol exposure

Changes in endogenous cannabinoid homeostasis are associated with both ethanol-related neuroinflammation and memory decline. Extensive research is still required to unveil the role of endocannabinoid signaling activation on hippocampal microglial cells after ethanol exposure. Either microglial morphology, phenotype and recruitment may become notably altered after chronic alcohol-related neurodegeneration. Here, we evaluated the pharmacological effects of fatty-acid amide-hydrolase (FAAH) inhibitor URB597 (0.3 mg/kg), oleoylethanolamide (OEA, 10 mg/kg), arachidonoylethanolamide (AEA, 10 mg/kg), the CB1 receptor agonist ACEA (3 mg/kg) and the CB2 receptor agonist JWH133 (0.2 mg/kg) administered for 5 days in a rat model of subchronic (2 weeks) ethanol diet (11% v/v) exposure. URB597 turned to be the most effective treatment. URB597 increased microglial (IBA-1+) cell population, and changed morphometric features (cell area and perimeter, roughness, fractal dimension, lacunarity) associated with activated microglia in the hippocampus of ethanol-exposed rats. Regarding innate immune activity, URB597 specifically increased mRNA levels of toll-like receptor 4 (TLR4), glial fibrillary acidic protein (Gfap) and the chemokine stromal cell-derived factor 1 (SDF-1α/CXCL12), and elevated the cell population expressing the chemokine receptors CX3CR1, CCR2 and CCR4 in the ethanol-exposed rat hippocampus. Contrary to ethanol effect, URB597 reduced mRNA levels of Iba-1, Tnfα, IL-6 and the monocyte chemoattractant protein-1 (MCP-1/CCL2), as well as cell population expressing iNOS. URB597 effects on hippocampal immune system were accompanied by changes in short and long-term visual recognition memory. These results suggest that FAAH inhibition may modulates hippocampal microglial recruitment and activation that can be associated with improved hippocampal-dependent memory despite ethanol exposure.

Inhibition of excessive autophagy and mitophagy mediates neuroprotective effects of URB597 against chronic cerebral hypoperfusion

URB597 (URB) has therapeutic potential for treating chronic cerebral hypoperfusion (CCH)-induced neuronal death. The present study investigated the protective effects of URB on autopahgy and mitophagy in a CCH model as well as the underlying mechanisms. The ultrastructural changes were examined by electron microscopy. The mitochondrial membrane potential was assessed by immunofluorescence. The expressions of autophagy-related proteins (beclin-1, p62, and LC3), lysosome-related proteins (CTSD and LAMP1), and mitophagy-related proteins (BNIP3, cyt C and parkin) were evaluated by western blotting, and the interaction of beclin-1 and Bcl-2 were determined by immunoprecipitation. CCH significantly decreased the protein expression of p62, CTSD, and LAMP1 and increased the protein expression of beclin-1, parkin, and BNIP3, the LC3-II to LC3-I ratio, and the release of cyt C from mitochondria to cytoplasm. Furthermore, CCH induced the accumulation of ubiquitinated proteins in PSDs. However, URB significantly reversed these results. Besides, URB significantly inhibited the beclin-1 from beclin-1/Bcl-2 complex to whole-cell lysates. The above results indicate that URB could inhibit impaired autophagy degradation and the disruption of beclin-1/Bcl-2 complex and subsequently cut off BNIP3-cyt C- and parkin-required mitophagy, finally preventing the abnormal excessive autophagy and mitophagy. These findings provide new insights that URB is a promising agent for therapeutic management of CCH.

The FAAH inhibitor URB597 suppresses hippocampal maximal dentate afterdischarges and restores seizure-induced impairment of short and long-term synaptic plasticity

Synthetic cannabinoids and phytocannabinoids have been shown to suppress seizures both in humans and experimental models of epilepsy. However, they generally have a detrimental effect on memory and memory-related processes. Here we compared the effect of the inhibition of the endocannabinoid (eCB) degradation versus synthetic CB agonist on limbic seizures induced by maximal dentate activation (MDA) acute kindling. Moreover, we investigated the dentate gyrus (DG) granule cell reactivity and synaptic plasticity in naïve and in MDA-kindled anaesthetised rats. We found that both the fatty acid amide hydrolase (FAAH) inhibitor URB597 and the synthetic cannabinoid agonist WIN55,212-2 displayed AM251-sensitive anti-seizure effects. WIN55,212-2, dose-dependently (0.5-2 mg/kg, i.p.) impaired short-term plasticity (STP) and long-term potentiation (LTP) at perforant path-DG synapses in naïve rats. Strikingly, URB597 (1 mg/kg, i.p.) was devoid of any deleterious effects in normal conditions, while it prevented seizure-induced alterations of both STP and LTP. Our evidence indicates that boosting the eCB tone rather than general CB1 activation might represent a potential strategy for the development of a new class of drugs for treatment of both seizures and comorbid memory impairments associated with epilepsy.

Cannabinoid receptor agonist WIN55,212-2 and fatty acid amide hydrolase inhibitor URB597 ameliorate neuroinflammatory responses in chronic cerebral hypoperfusion model by blocking NF-κB pathways

The present study explored the protective effects of cannabinoid receptor agonist WIN55,212-2 (WIN) and fatty acid amide hydrolase inhibitor URB597 (URB) against neuroinflammation in rats with chronic cerebral hypoperfusion (CCH). Activated microglia, astrocytes, and nuclear factor kappa B (NF-κB) p65-positive cells were measured by immunofluorescence. Reactive oxygen species (ROS) was assessed by dihydroethidium staining. The protein levels of cluster of differentiation molecule 11b (OX-42), glial fibrillary acidic protein (GFAP), NF-κB p65, inhibitor of kappa B alpha (IκB-a), IκB kinase a/β (IKK a/β), phosphorylated IKK a/β (p-IKK a/β), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and interleukin-1β (IL-1β) were examined by western blotting or enzyme-linked immunosorbent assay. All the protein levels of OX-42, GFAP, TNF-a, IL-1β, COX-2, and iNOS are increased in CCH rats. WIN and URB downregulated the levels of OX-42, GFAP, TNF-α, IL-1β, COX-2 and iNOS and inhibited CCH-induced ROS accumulation in CCH rats, indicating that WIN and URB might exert their neuroprotective effects by inhibiting the neuroinflammatory response. In addition, the NF-κB signaling pathway was activated by CCH in frontal cortex and hippocampus, while the aforementioned changes were reversed by WIN and URB treatment. These findings suggest that WIN and URB treatment ameliorated CCH-induced neuroinflammation through inhibition of the classical pathway of NF-κB activation, resulting in mitigation of chronic ischemic injury.

Phytoceramide ameliorates ß-amyloid protein-induced memory impairment and neuronal death in mice

The present study was performed to investigate the protective effect of phytoceramide against ß-amyloid protein (Aβ) (25-35)-induced memory impairment and its underlying mechanisms in mice. Memory impairment in mice was induced by intracerebroventricular injection of 15 nmol Aβ (25-35) and measured by the passive avoidance test and Morris water maze test. Chronic administration of phytoceramide (10, 25 and 50 mg/kg, p.o.) resulted in significantly less Aβ (25-35)-induced memory loss and hippocampal neuronal death in treated mice compared to controls. The decrease of glutathione level and increase of lipid peroxidation in brain tissue following injection of Aβ (25-35) was reduced by phytoceramide. Alteration of apoptosis-related proteins, increase of inflammatory factors, and phosphorylation of mitogen activated proteins kinases (MAPKs) in Aβ (25-35)-administered mice hippocampus were inhibited by phytoceramide. Phosphatidylinositol 3'-kinase (PI3K)/Akt pathway and phosphorylation of cyclic AMP response element-binding protein (CREB) were suppressed, while phosphorylation of tau (p-tau) was increased in Aß (25-35)-treated mice brain; these effects were significantly inhibited by administration of phytoceramide. These results suggest that phytoceramide has a possible therapeutic role in managing cognitive impairment associated with Alzheimer's disease. The underlying mechanism might involve inhibition of p-tau formation via anti-apoptosis and anti-inflammation activity and promotion of PI3K/Akt/CREB signaling process.

Chronic inhibition of fatty acid amide hydrolase by URB597 produces differential effects on cardiac performance in normotensive and hypertensive rats

BACKGROUND AND PURPOSE

Fatty acid amide hydrolase (FAAH) inhibitors are postulated to possess anti-hypertensive potential, because their acute injection decreases BP in spontaneously hypertensive rats (SHR), partly through normalization of cardiac contractile function. Here, we examined whether the potential hypotensive effect of chronic FAAH inhibition by URB597 in hypertensive rats correlated with changes in cardiac performance.

EXPERIMENTAL APPROACH

Experiments were performed using perfused hearts and left atria isolated from 8- to 10-week-old SHR, age-matched deoxycorticosterone acetate (DOCA)-salt rats and normotensive controls chronically treated with URB597 (1 mg·kg^-1 ) or vehicle.

KEY RESULTS

URB597 decreased BP only in the DOCA-salt rats, along with a reduction of ventricular hypertrophy and diastolic stiffness, determined in hypertension. We also observed normalization of the negative inotropic atrial response to the cannabinoid receptor agonist CP55940. In the SHR model, URB597 normalized (atria) and enhanced (hearts) the positive ino- and chronotropic effects of the β-adrenoceptor agonist isoprenaline respectively. Ventricular CB₁ and CB₂ receptor expression was decreased only in the DOCA-salt model, whereas FAAH expression was reduced in both models. URB597 caused translocation of CB₁ receptor immunoreactivity to the intercalated discs in the hearts of SHR. URB597 increased cardiac diastolic stiffness and modified the ino- and lusitropic effects of isoprenaline in normotensive rats.

CONCLUSION AND IMPLICATIONS

Hypotensive effect of chronic FAAH inhibition depend on the model of hypertension and partly correlate with improved cardiac performance. In normotensive rats, chronic FAAH inhibition produced several side-effects. Thus, the therapeutic potential of these agents should be interpreted cautiously.

Autophagy and Akt/CREB signalling play an important role in the neuroprotective effect of nimodipine in a rat model of vascular dementia

The Akt/CREB signalling pathway is involved in neuronal survival and protection. Autophagy is also likely to be involved in survival mechanisms. Nimodipine is an L-type calcium channel antagonist that reduces excessive calcium influx during pathological conditions (contributing to its neuroprotective properties). However, the potential role of nimodipine in autophagic and Akt/CREB signalling is not well understood. In addition, little is known about the relationship between autophagic and Akt/CREB signalling. Here, we designed a way to evaluate these issues. Adult male Sprague-Dawley rats were subjected to permanent bilateral occlusion of the common carotid artery (2VO) and randomly divided into three groups: the Vehicle (2VO), Nimodipine10 (2VO+nimodipine 10mg/kg), and Nimodipine20 (2VO+nimodipine 20mg/kg) groups. A fourth group of animals served as Sham controls. Each group was investigated at 4 and 8 weeks post-operatively and assessed using the Morris water maze. Nimodipine significantly alleviated spatial learning and memory impairments and inhibited the loss of neurons in the CA1 region of the hippocampus. These drug effects were more pronounced at 8 weeks than at 4 weeks. The activities of LC3 II p-Akt and p-CREB were examined using immunohistochemistry and western blotting. Suppressing autophagy induced pyramidal cell death without affecting increased pro-survival signalling induced by nimodipine. Nimodipine protected the brain from chronic cerebral hypoperfusion by activating the Akt/CREB signalling pathway. Autophagy has a neuroprotective effect on rats after 2VO. Autophagy is likely part of an integrated survival signalling network involving the Akt/CREB pathway.

Inhibition of SENP3 by URB597 ameliorates neurovascular unit dysfunction in rats with chronic cerebral hypoperfusion

Disruption of the neurovascular unit (NVU), induced by chronic cerebral hypoperfusion (CCH), has been broadly found in various neurological disorders. SUMO-specific protease 3 (SENP3) is expressed in neurons, astrocytes, and microglia, and regulates a variety of cell events. However, whether SENP3 is involved in neurovascular injury under the condition of CCH is still elusive. To address this issue, we investigated the effect of the fatty acid amide hydrolase (FAAH) inhibitor URB597 on NVU and the role of SENP3 in this process, as well as the underling mechanisms. The expression of SENP3 was detected by immunochemistry. The function and structure of the NVU was assessed by Western blot analysis and transmission electron microscopy. CCH caused the upregulation of SENP3, the disruption of cell and non-cell components at the protein level within the NVU, and ultrastructural deterioration. The NVU impairment as well as overexpression of SENP3 were reversed by treatment with URB597. These results reveal a novel neuroprotective role in URB597, which implicates URB597 in the amelioration of CCH-induced NVU impairment by inhibiting SENP3.

URB597 improves cognitive impairment induced by chronic cerebral hypoperfusion by inhibiting mTOR-dependent autophagy

Chronic cerebral hypoperfusion (CCH) is associated with various ischemic cerebrovascular diseases that are characterized by cognitive impairment. The role of autophagy in cognitive dysfunction under conditions of CCH is poorly understood. To address this issue, the present study investigated the effect of the fatty acid amide hydrolase (FAAH) inhibitor URB597 on autophagy and cognition in a CCH model as well as the underlying mechanisms. Cognitive function was evaluated with the Morris water maze and by assessing long-term potentiation (LTP). The expression of autophagy-related proteins and mammalian target of rapamycin (mTOR) signaling pathway components was evaluated by immunofluorescence and western blot analyses, and ultrastructural changes were examined by transmission electron microscopy (EM). URB597 improved cognitive impairment by inhibiting CCH-induced autophagy, which was associated with mTOR signaling. Moreover, the ultrastructural deterioration resulting from CCH was improved by chronic treatment with URB597. These findings indicate that URB597 modulates autophagy in an mTOR-dependent manner, and mitigates neuronal damage and cognitive deterioration caused by CCH.