Inhibition of mitochondrial permeability transition pore opening contributes to cannabinoid type 1 receptor agonist ACEA-induced neuroprotection

Tom70-regulated mitochondrial biogenesis via TFAM improves hypoxia-induced dysfunction of pulmonary vascular endothelial cells and alleviates hypoxic pulmonary hypertension

BACKGROUND

Hypoxic pulmonary hypertension (HPH) is a common type of pulmonary hypertension and characterized by pulmonary vascular remodeling and constriction. A large number of studies have shown that pulmonary vascular endothelial cells (PVECs) dysfunction plays an important role in the initiation and development stages of HPH, but the mechanism of PVECs dysfunction after hypoxia remains unclear. In this study, we explored the exact mechanism of PVECs dysfunction after hypoxia.

METHODS

In vitro, we used primary cultured PVECs hypoxia model to mimic HPH injury. We detected the expressions of mitochondrial biogenesis markers, mitochondrial transcription factor A (TFAM) level inside mitochondria, mitochondrial quantity and function, and the components expressions of translocase of outer mitochondrial membrane (TOM) at 24 h after hypoxia. To explore the effects of Tom70 on mitochondrial biogenesis and functions of PVECs after hypoxia, Tom70 overexpression adenovirus was constructed, and the expressions of mitochondrial biogenesis markers, TFAM level inside mitochondria, mitochondrial quantity and function, and the functions of PVECs were detected. And in vivo, we used cre-dependent overexpression adenovirus of Tom70 in the Cdh5-CreERT2 mouse model of HPH to verify the role of upregulating PVECs Tom70 in improving HPH.

RESULTS

Hypoxia obviously increased the expressions of mitochondrial biogenesis markers for PGC-1α, NRF-1 and TFAM, but reduced the content of TFAM in mitochondria and the quantity and functions of mitochondria. In addition, only Tom70 expression among the TOM components was significantly decreased after hypoxia, and up-regulation of Tom70 significantly increased the content of TFAM in mitochondria of PVECs by transporting TFAM into mitochondria after hypoxia, enhanced the quantity and functions of mitochondria, improved the functions of PVECs, and ultimately alleviated HPH.

CONCLUSION

The findings of present study demonstrated that hypoxia induced the decreased expression of Tom70 in PVECs, reduced the mitochondrial biogenesis-associated TFAM protein transporting into mitochondria, inhibited mitochondrial biogenesis, caused PVECs injury, and prompted the formation of HPH. However, up-regulation of Tom70 abolished the hypoxia-induced injurious effects on PVECs and alleviated HPH.

Study on the mechanism of Wuzi-Yanzong-Wan-medicated serum interfering with the mitochondrial permeability transition pore in the GC-2 cell induced by atractyloside

Wuzi-Yanzong-Wan (WZYZW) is a classic prescription for male infertility. Our previous investigation has demonstrated that it can inhibit sperm apoptosis via affecting mitochondria, but the underlying mechanisms are unclear. The purpose of the present study was to explore the actions of WZYZW on mitochondrial permeability transition pore (mPTP) in mouse spermatocyte cell line (GC-2 cells) opened by atractyloside (ATR). At first, WZYZW-medicated serum was prepared from rats following oral administration of WZYZW for 7 days. GC-2 cells were divided into control group, model group, positive group, as well as 5%, 10%, 15% WZYZW-medicated serum group. Cyclosporine A (CsA) was used as a positive control. 50 μmol·L-1 ATR was added after drugs incubation. Cell viability was assessed using CCK-8. Apoptosis was detected using flow cytometry and TUNEL method. The opening of mPTP and mitochondrial membrane potential (MMP) were detected by Calcein AM and JC-1 fluorescent probe respectively. The mRNA and protein levels of voltage-dependent anion channel 1 (VDAC1), cyclophilin D (CypD), adenine nucleotide translocator (ANT), cytochrome C (Cyt C), caspase 3, 9 were detected by RT-PCR (real time quantity PCR) and Western blotting respectively. The results demonstrated that mPTP of GC-2 cells was opened after 24 hours of ATR treatment, resulting in decreased MMP and increased apoptosis. Pre-protection with WZYZ-medicated serum and CsA inhibited the opening of mPTP of GC-2 cells induced by ATR associated with increased MMP and decreased apoptosis. Moreover, the results of RT-qPCR and WB suggested that WZYZW-medicated serum could significantly reduce the mRNA and protein levels of VDAC1 and CypD, Caspase-3, 9 and CytC, as well as a increased ratio of Bcl/Bax. However, ANT was not significantly affected. Therefore, these findings indicated that WZYZW inhibited mitochondrial mediated apoptosis by attenuating the opening of mPTP in GC-2 cells. WZYZW-medicated serum inhibited the expressions of VDAC1 and CypD and increased the expression of Bcl-2, which affected the opening of mPTP and exerted protective and anti-apoptotic effects on GC-2 cell induced by ATR.

Chronic unpredictable stress during adolescence protects against adult traumatic brain injury-induced affective and cognitive deficits

Pre-clinical early-life stress paradigms model early adverse events in humans. However, the long-term behavioral consequences of early-life adversities after traumatic brain injury (TBI) in adults have not been examined. In addition, endocannabinoids may protect against TBI neuropathology. Hence, the current study assessed the effects of adverse stress during adolescence on emotional and cognitive performance in rats sustaining a TBI as adults, and how cannabinoid receptor 1 (CB1) activation impacts the outcome. On postnatal days (PND) 30-60, adolescent male rats were exposed to four weeks of chronic unpredictable stress (CUS), followed by four weeks of no stress (PND 60-90), or no stress at any time (Control), and then anesthetized and provided a cortical impact of moderate severity (2.8 mm tissue deformation at 4 m/s) or sham injury. TBI and Sham rats (CUS and Control) were administered either arachidonyl-2'-chloroethylamide (ACEA; 1 mg/kg, i.p.), a CB1 receptor agonist, or vehicle (VEH; 1 mL/kg, i.p.) immediately after surgery and once daily for 7 days. Anxiety-like behavior was assessed in an open field test (OFT) and learning and memory in novel object recognition (NOR) and Morris water maze (MWM) tasks. No differences were revealed among the Sham groups in any behavioral assessment and thus the groups were pooled. In the ACEA and VEH-treated TBI groups, CUS increased exploration in the OFT, enhanced NOR focus, and decreased the time to reach the escape platform in the MWM, suggesting decreased anxiety and enhanced learning and memory relative to the Control group receiving VEH (p < 0.05). ACEA also enhanced NOR and MWM performance in the Control + TBI group (p < 0.05). These data suggest that 4 weeks of CUS provided during adolescence may provide protection against TBI acquired during adulthood and/or induce adaptive behavioral responses. Moreover, CB1 receptor agonism produces benefits after TBI independent of CUS protection.

G-Protein-Coupled Receptors and Ischemic Stroke: a Focus on Molecular Function and Therapeutic Potential

In ischemic stroke, there is only one approved drug, tissue plasminogen activator, to be used in clinical conditions for thrombolysis. New neuroprotective therapies for ischemic stroke are desperately needed. Several targets and pathways have been shown to confer neuroprotective effects in ischemic stroke. G-protein-coupled receptors (GPCRs) are one of the most frequently targeted receptors for developing novel therapeutics for central nervous system disorders. GPCRs are a large family of cell surface receptors that response to a wide variety of extracellular stimuli. GPCRs are involved in a wide range of physiological and pathological processes. More than 90% of the identified non-sensory GPCRs are expressed in the brain, where they play important roles in regulating mood, pain, vision, immune responses, cognition, and synaptic transmission. There is also good evidence that GPCRs are implicated in the pathogenesis of stroke. This review narrates the pathophysiological role and possible targeted therapy of GPCRs in ischemic stroke.

Multi-Target Effects of the Cannabinoid CP55940 on Familial Alzheimer's Disease PSEN1 E280A Cholinergic-Like Neurons: Role of CB1 Receptor

BACKGROUND

Alzheimer's disease (AD) is characterized by structural damage, death, and functional disruption of cholinergic neurons (ChNs) as a result of intracellular amyloid-β (Aβ) aggregation, extracellular neuritic plaques, and hyperphosphorylation of protein tau (p-Tau) overtime.

OBJECTIVE

To evaluate the effect of the synthetic cannabinoid CP55940 (CP) on PSEN1 E280A cholinergic-like nerve cells (PSEN1 ChLNs)-a natural model of familial AD.

METHODS

Wild type (WT) and PSEN1 ChLNs were exposed to CP (1μM) only or in the presence of the CB1 and CB2 receptors (CB1Rs, CB2Rs) inverse agonist SR141716 (1μM) and SR144528 (1μM) respectively, for 24 h. Untreated or treated neurons were assessed for biochemical and functional analysis.

RESULTS

CP in the presence of both inverse agonists (hereafter SR) almost completely inhibits the aggregation of intracellular sAβPPβf and p-Tau, increases ΔΨm, decreases oxidation of DJ-1Cys106-SH residue, and blocks the activation of c-Jun, p53, PUMA, and caspase-3 independently of CB1Rs signaling in mutant ChLNs. CP also inhibits the generation of reactive oxygen species partially dependent on CB1Rs. Although CP reduced extracellular Aβ42, it was unable to reverse the Ca2+ influx dysregulation as a response to acetylcholine stimuli in mutant ChLNs. Exposure to anti-Aβ antibody 6E10 (1:300) in the absence or presence of SR plus CP completely recovered transient [Ca2+]i signal as a response to acetylcholine in mutant ChLNs.

CONCLUSION

Taken together our findings suggest that the combination of cannabinoids, CB1Rs inverse agonists, and anti-Aβ antibodies might be a promising therapeutic approach for the treatment of familial AD.

Cannabinoid CB1 receptor agonist ACEA alleviates brain ischemia/reperfusion injury via CB1-Drp1 pathway

Activation of the cannabinoid CB1 receptor induces neuroprotection against brain ischemia/reperfusion injury (IRI); however, the mechanism is still unknown. In this study, we used oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in neuronal cells and middle cerebral artery occlusion (MCAO)-induced brain IRI in rats to mimic ischemic brain injury, and hypothesized that the CB1 receptor agonist arachidonyl-2-chloroethylamide (ACEA) would protect ischemic neurons by inhibiting mitochondrial fission via dynamin-related protein 1 (Drp1). We found that OGD/R injury reduced cell viability and mitochondrial function, increased lactate dehydrogenase (LDH) release, and increased cell apoptosis, and mitochondrial fission. Notably, ACEA significantly abolished the OGD/R-induced neuronal injuries described above. Similarly, ACEA significantly reversed MCAO-induced increases in brain infarct volume, neuronal apoptosis and mitochondrial fission, leading to the recovery of neurological functions. The neuroprotective effects of ACEA were obviously blocked by coadministration of the CB1 receptor antagonist AM251 or by the upregulation of Drp1 expression, indicating that ACEA alleviates brain IRI via the CB1-Drp1 pathway. Our findings suggest that the CB1 receptor links aberrant mitochondrial fission to brain IRI, providing a new therapeutic target for brain IRI treatment.

Melatonin and cannabinoids: mitochondrial-targeted molecules that may reduce inflammaging in neurodegenerative diseases

Generally, the development and progression of neurodegenerative diseases are associated with advancing age, so they are usually diagnosed in late adulthood. A primary mechanism underlying the onset of neurodegenerative diseases is neuroinflammation. Based on this background, the concept of "neuroinflammaging" has emerged. In this deregulated neuroinflammatory process, a variety of immune cells participate, especially glial cells, proinflammatory cytokines, receptors, and subcellular organelles including mitochondria, which are mainly responsible for maintaining redox balance at the cellular level. Senescence and autophagic processes also play a crucial role in the neuroinflammatory disease associated with aging. Of particular interest, melatonin, cannabinoids, and the receptors of both molecules which are closely related, exert beneficial effects on the neuroinflammatory processes that precede the onset of neurodegenerative pathologies such as Parkinson's and Alzheimer's diseases. Some of these neuroprotective effects are fundamentally related to its anti-inflammatory and antioxidative actions at the mitochondrial level due to the strategic functions of this organelle. The aim of this review is to summarize the most recent advances in the study of neuroinflammation and neurodegeneration associated with age and to consider the use of new mitochondrial therapeutic targets related to the endocannabinoid system and the pineal gland.

Tumor Necrosis Factor Receptor-Associated Protein 1 Protects against Mitochondrial Injury by Preventing High Glucose-Induced mPTP Opening in Diabetes

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide. Renal tubular epithelial cell apoptosis and tubular atrophy have been recognized as indicators of the severity and progression of DKD, while the mechanism remains elusive. Tumor necrosis factor receptor-associated protein 1 (TRAP1) plays critical roles in apoptosis. The aim of this study was to investigate the protective role TRAP1 plays in DKD and to study the potential underlying mechanisms. TRAP1 expression was decreased, and mitochondria were injured in NRK-52e cells under high-glucose (HG) conditions. The overexpression of TRAP1 ameliorated HG-induced apoptosis, increased cell viability, maintained mitochondrial morphology, adenosine triphosphate (ATP) levels, and mitochondrial membrane potential (MMP), and buffered oxidative stress, whereas TRAP1 knockdown aggravated these effects. The protective effects of TRAP1 may be exerted via the inhibition of mitochondrial permeability transition pore (mPTP) opening, and the damage caused by TRAP1 knockdown can be partially reversed by treatment with the mPTP opening inhibitor cyclosporin A (CsA). In vivo, TRAP1 expression upregulation by AAV2/9 injection prevented renal dysfunction, ameliorated histopathological changes, maintained mitochondrial morphology and function, and reduced apoptosis and reactive oxygen species (ROS) in STZ-treated DKD rats. Thus, our results suggest that TRAP1 ameliorates diabetes-induced renal injury by preventing abnormal mPTP opening and maintaining mitochondrial structure and function, which may be treated as a potential target for DKD treatment.

Strategies for Neuroprotection in Multiple Sclerosis and the Role of Calcium

Calcium ions are vital for maintaining the physiological and biochemical processes inside cells. The central nervous system (CNS) is particularly dependent on calcium homeostasis and its dysregulation has been associated with several neurodegenerative disorders including Parkinson’s disease (PD), Alzheimer’s disease (AD) and Huntington’s disease (HD), as well as with multiple sclerosis (MS). Hence, the modulation of calcium influx into the cells and the targeting of calcium-mediated signaling pathways may present a promising therapeutic approach for these diseases. This review provides an overview on calcium channels in neurons and glial cells. Special emphasis is put on MS, a chronic autoimmune disease of the CNS. While the initial relapsing-remitting stage of MS can be treated effectively with immune modulatory and immunosuppressive drugs, the subsequent progressive stage has remained largely untreatable. Here we summarize several approaches that have been and are currently being tested for their neuroprotective capacities in MS and we discuss which role calcium could play in this regard.

Sevoflurane postconditioning improves spatial learning and memory ability involving mitochondrial permeability transition pore in hemorrhagic shock and resuscitation rats

BACKGROUND

Hemorrhagic shock induces the cognitive deficiency. Sevoflurane postconditioning has been documented to provide neuroprotection against ischemic-reperfusion injury by suppressing apoptosis. Mitochondrial permeability transition pore (mPTP) plays an important role in apoptosis, but it is unknown if the protective effect of sevoflurane postconditioning on hemorrhagic shock and resuscitation is associated with the change of mPTP opening. Hence, the aim of the study was to find out the precise mechanism of the sevoflurane postconditioning.

METHODS

Sprague Dawley rats were subjected to hemorrhage shock for 60 min and then exposed to 2.4% sevoflurane for 30 min at the instant of reperfusion. Additionally, an opener (atractyloside) or an inhibitor (cyclosporine A) of mPTP was used in the animal model before sevoflurane postconditioning. Rats were randomly assigned into groups of Sham, Shock, Shock+Sevoflurane, Shock+Atractyloside, Shock+Sevoflurane+Atractyloside, Shock+Cyclosporin A, and Shock+Sevoflurane+Cyclosporin A treatment. Rat behavior was assessed for 5 days by Morris water maze 72 hr after surgery, and then hippocampus CA1 region was immunohistochemically stained. Brains were harvested 24 hr after surgery to detect the protein expression levels of Bcl-2, Bax, and cytochrome C by Western blot, the changes of mPTP opening, and mitochondrial membrane potential (MMP).

RESULTS

We found that sevoflurane postconditioning significantly improved rats' spatial learning and memory ability, down-regulated the expression of Bax, cytochrome C, and caspase-3, up-regulated the expression of Bcl-2, decreased the mPTP opening, and increased the MMP. The neuroprotective effect of sevoflurane postconditioning was abolished by atractyloside, but cyclosporin A played the similar protective role as sevoflurane postconditioning.

CONCLUSION

These findings proved that sevoflurane postconditioning improved spatial learning and memory ability in hemorrhage shock and resuscitation rats, the mechanism of which may be related to block mPTP opening, increase MMP, and reduce neuron apoptosis in the hippocampus.

SOD2 Mediates Curcumin-Induced Protection against Oxygen-Glucose Deprivation/Reoxygenation Injury in HT22 Cells

Curcumin (Cur) induces neuroprotection against brain ischemic injury; however, the mechanism is still obscure. The aim of this study is to explore the potential neuroprotective mechanism of curcumin against oxygen-glucose deprivation/reoxygenation (OGD/R) injury in HT22 cells and investigate whether type-2 superoxide dismutase (SOD2) is involved in the curcumin-induced protection. In the present study, HT22 neuronal cells were treated with 3 h OGD plus 24 h reoxygenation to mimic ischemia/reperfusion injury. Compared with the normal cultured control group, OGD/R treatment reduced cell viability and SOD2 expression, decreased mitochondrial membrane potential (MMP) and mitochondrial complex I activity, damaged cell morphology, and increased lactic dehydrogenase (LDH) release, cell apoptosis, intracellular reactive oxygen species (ROS), and mitochondrial superoxide (P < 0.05). Meanwhile, coadministration of 100 ng/ml curcumin reduced the cell injury and apoptosis, inhibited intracellular ROS and mitochondrial superoxide accumulation, and ameliorated intracellular SOD2, cell morphology, MMP, and mitochondrial complex I activity. Downregulating the SOD2 expression by using siRNA, however, significantly reversed the curcumin-induced cytoprotection (P < 0.05). These findings indicated that curcumin induces protection against OGD/R injury in HT22 cells, and SOD2 protein may mediate the protection.

Role of PGC-1α in Mitochondrial Quality Control in Neurodegenerative Diseases

As one of the major cell organelles responsible for ATP production, it is important that neurons maintain mitochondria with structural and functional integrity; this is especially true for neurons with high metabolic requirements. When mitochondrial damage occurs, mitochondria are able to maintain a steady state of functioning through molecular and organellar quality control, thus ensuring neuronal function. And when mitochondrial quality control (MQC) fails, mitochondria mediate apoptosis. An apparently key molecule in MQC is the transcriptional coactivator peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α). Recent findings have demonstrated that upregulation of PGC-1α expression in neurons can modulate MQC to prevent mitochondrial dysfunction in certain in vivo and in vitro aging or neurodegenerative encephalopathy models, such as Huntington's disease, Alzheimer's disease, and Parkinson's disease. Because mitochondrial function and quality control disorders are the basis of pathogenesis in almost all neurodegenerative diseases (NDDs), the role of PGC-1α may make it a viable entry point for the treatment of such diseases. This review focuses on multi-level MQC in neurons, as well as the regulation of MQC by PGC-1α in these major NDDs.

Cannabinoid receptors as therapeutic targets for autoimmune diseases: where do we stand?

Described during the late 1980s and 1990s, cannabinoid receptors (CB1R and CB2R) are G-protein-coupled receptors (GPCRs) activated by endogenous ligands and cannabinoid drug compounds, such as Δ9-THC. Whereas CB1R has a role in the regulation of neurotransmission in different brain regions and mainly mediates the psychoactive effects of cannabinoids, CB2R is found predominantly in the cells and tissues of the immune system and mediates anti-inflammatory and immunomodulatory processes. Studies have demonstrated that CB1R and CB2R can affect the activation of T cells, B cells, monocytes, and microglial cells, inhibiting proinflammatory cytokine expression and upregulating proresolution mediators. Thus, in this review, we summarize the mechanisms by which CBRs interact with the autoimmune environment and the potential to suppress the development and activation of autoreactive cells. Finally, we highlight how the modulation of CB1R and CB2R is advantageous in the treatment of autoimmune diseases, including multiple sclerosis (MS), type 1 diabetes mellitus (T1DM) and rheumatoid arthritis (RA).

Curcumin Alleviates β Amyloid-Induced Neurotoxicity in HT22 Cells via Upregulating SOD2

Curcumin protects neuronal cells exposed to β amyloid (Aβ); the mechanism, however, is still obscure. The aim of this study is to determine whether the type 2 superoxide dismutase (SOD2) mediates curcumin-induced protective effects in Aβ-treated neuronal cells. In this study, the HT22 neuronal cells were exposed to Aβ to imitate neuronal injury in Alzheimer's disease (AD). After 24-h treatment, 10 μM Aβ decreased cell viability and mitochondrial functions, including mitochondrial complex activities and mitochondrial membrane potential (MMP), and also downregulated anti-oxidants SOD2, glutathione (GSH), and catalase (CAT) levels (P < 0.05), meanwhile, increased lactic dehydrogenase (LDH) release, apoptosis level, intracellular reactive oxygen species (ROS) and mitochondrial superoxide accumulation (P < 0.05). And, co-administration of 1 μM curcumin significantly reduced the Aβ-induced cell injury and oxidative damage above (P < 0.05). Downregulating SOD2 by using small interfering RNA (siRNA), however, significantly abolished the curcumin-induced protective and anti-oxidative effects in HT22 cells (P < 0.05); the scramble (SC)-siRNA did not cause marked effects on the curcumin-induced protective effects (P > 0.05). These findings showed that curcumin can alleviate Aβ-induced injury in neuronal cells, and SOD2 protein may mediate the neuroprotective effects.

Levetiracetam combined with ACEA, highly selective cannabinoid CB1 receptor agonist changes neurogenesis in mouse brain

The aim of the study was to evaluate the impact of second generation antiepileptic drug levetiracetam (LEV) with arachidonyl-2'-chloroethylamide (ACEA) on proliferating neural precursor cells in mouse brain. Additionally, we established the relationship between treatment with ACEA in combination with LEV and hippocampal neurogenesis in mouse brain. All experiments were performed on male CB57/BL mice injected i.p. with LEV (10 mg/kg), ACEA (10 mg/kg) and PMSF (30 mg/kg) for 10 days. Experiments were provided in two stages: stage 1- an acute response of proliferating neural precursor cells to ACEA and LEV administration (Ki-67 staining), stage 2 - a long term response to ACEA and LEV administration (BrDU, NeuN, GFAP staining). Results indicate that ACEA + PMSF and ACEA + PMSF + LEV significantly increased the total number of Ki-67 positive cells comparing to the control group. PMSF and LEV administered alone and in combination had no significant impact on cell proliferation compared to the control group. Results from neurogenesis study indicated that ACEA + PMSF administered alone and in combination with LEV increased the total number of BrDU cells compared to the control group, although LEV on its own decreased the number of BrDU cells. Moreover, the combination of ACEA + PMSF + LEV significantly increased the total number of newborn neurons compared to the control group. In turn, LEV significantly decreased the process of neurogenesis. Astrocytes were considerably reduced in all treated groups as compare to the control mice. These data provide substantial evidence that LEV administered chronically decreases the proliferation and differentiation of newly born cells while combination of LEV + ACEA significantly increases the level of newborn neurons in the dentate subgranular zone.

[Mitochondrial signaling of G protein-coupled receptors]

G protein-coupled receptors (GPCRs) are the largest family of integral membrane receptors with 800 members in humans that are expressed at the cell surface responding to a large panel of extracellular stimuli. Recent advances indicate that GPCRs are also expressed in intracellular compartments where they fulfil important functions. Here, we will report on the mitochondrial localization and function of GPCRs.