Inhibitor of Endocannabinoid Deactivation Protects Against In Vitro and In Vivo Neurotoxic Effects of Paraoxon

Advances in Material-Assisted Electromagnetic Neural Stimulation

Bioelectricity plays a crucial role in organisms, being closely connected to neural activity and physiological processes. Disruptions in the nervous system can lead to chaotic ionic currents at the injured site, causing disturbances in the local cellular microenvironment, impairing biological pathways, and resulting in a loss of neural functions. Electromagnetic stimulation has the ability to generate internal currents, which can be utilized to counter tissue damage and aid in the restoration of movement in paralyzed limbs. By incorporating implanted materials, electromagnetic stimulation can be targeted more accurately, thereby significantly improving the effectiveness and safety of such interventions. Currently, there have been significant advancements in the development of numerous promising electromagnetic stimulation strategies with diverse materials. This review provides a comprehensive summary of the fundamental theories, neural stimulation modulating materials, material application strategies, and pre-clinical therapeutic effects associated with electromagnetic stimulation for neural repair. It offers a thorough analysis of current techniques that employ materials to enhance electromagnetic stimulation, as well as potential therapeutic strategies for future applications.

Lifestyle strategies to promote proteostasis and reduce the risk of Alzheimer's disease and other proteinopathies

Unhealthy lifestyle choices, poor diet, and aging can have negative influences on cognition, gradually increasing the risk for mild cognitive impairment (MCI) and the continuum comprising early dementia. Aging is the greatest risk factor for age-related dementias such as Alzheimer's disease, and the aging process is known to be influenced by life events that can positively or negatively affect age-related diseases. Remarkably, life experiences that make the brain vulnerable to dementia, such as seizure episodes, neurotoxin exposures, metabolic disorders, and trauma-inducing events (e.g. traumatic injuries or mild neurotrauma from a fall or blast exposure), have been associated with negative effects on proteostasis and synaptic integrity. Functional compromise of the autophagy-lysosomal pathway, a major contributor to proteostasis, has been implicated in Alzheimer's disease, Parkinson's disease, obesity-related pathology, Huntington's disease, as well as in synaptic degeneration which is the best correlate of cognitive decline. Correspondingly, pharmacological and non-pharmacological strategies that positively modulate lysosomal proteases are recognized as synaptoprotective through degradative clearance of pathogenic proteins. Here, we discuss life-associated vulnerabilities that influence key hallmarks of brain aging and the increased burden of age-related dementias. Additionally, we discuss exercise and diet among the lifestyle strategies that regulate proteostasis as well as synaptic integrity, leading to evident prevention of cognitive deficits during brain aging in pre-clinical models.

Therapeutic Molecular Insights into the Active Engagement of Cannabinoids in the Therapy of Parkinson's Disease: A Novel and Futuristic Approach

Parkinson's disease is a neurodegenerative disorder which is characterised mostly by loss of dopaminergic nerve cells throughout the nigral area mainly as a consequence of oxidative stress. Muscle stiffness, disorganised bodily responses, disturbed sleep, weariness, amnesia, and voice impairment are all symptoms of dopaminergic neuron degeneration and existing symptomatic treatments are important to arrest additional neuronal death. Some cannabinoids have recently been demonstrated as robust antioxidants that might protect the nerve cells from degeneration even when cannabinoid receptors are not triggered. Cannabinoids are likely to have property to slow or presumably cease the steady deterioration of the brain's dopaminergic systems, a condition for which there is now no treatment. The use of cannabinoids in combination with currently available drugs has the potential to introduce a radically new paradigm for treatment of Parkinson's disease, making it immensely useful in the treatment of such a debilitating illness.

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.

rLj-RGD4, the shortened peptide of rLj-RGD3 from Lampetra japonica, protects against cerebral ischemia/reperfusion injury via the PI3K/Akt pathway

The toxic RGD peptide, rLj-RGD4, characterized by 4 (Arg-Gly-Asp) (RGD) motifs, is a novel mutant of rLj-RGD3 from the salivary gland of Lampetra japonica. Our previous study showd that rLj-RGD3 exerts a protective effect against cerebral ischemia injury in rats. Through the induction of middle cerebral artery occlusion/reperfusion (MCAO) injuries in rats, the present study investigated the effects and the mechanism through which rLj-RGD4 protects against ischemic stroke. In rats, treatment with rLj-RGD4 2 h after MCAO enhanced survival rate, improved movement and ameliorated the severity of brain infarction and apoptosis by diminishing pathological changes. This study demonstrated that rLj-RGD4 can reverse the downregulation of Bcl2, and the upregulation of Caspase-3. Mechanistic studies showed that rLj-RGD4 upregulated the expression levels of FAK, p-FAK, PI3K and p-Akt. In contrast, caspase-3 expression was inhibited. These results showed that rLj-RGD4 may reduce cerebral ischemia-reperfusion injury.

The Endocannabinoid System and Synthetic Cannabinoids in Preclinical Models of Seizure and Epilepsy

Cannabinoids are compounds that are structurally and/or functionally related to the primary psychoactive constituent of Cannabis sativa, [INCREMENT]-tetrahydrocannabinol (THC). Cannabinoids can be divided into three broad categories: endogenous cannabinoids, plant-derived cannabinoids, and synthetic cannabinoids (SCs). Recently, there has been an unprecedented surge of interest into the pharmacological and medicinal properties of cannabinoids for the treatment of epilepsies. This surge has been stimulated by an ongoing shift in societal opinions about cannabinoid-based medicines and evidence that cannabidiol, a nonintoxicating plant cannabinoid, has demonstrable anticonvulsant activity in children with treatment-refractory epilepsy. The major receptors of the endogenous cannabinoid system (ECS)-the type 1 and 2 cannabinoid receptors (CB1R, CB2R)-have critical roles in the modulation of neurotransmitter release and inflammation, respectively; so, it is not surprising therefore that the ECS is being considered as a target for the treatment of epilepsy. SCs were developed as potential new drug candidates and tool compounds for studying the ECS. Beyond the plant cannabinoids, an extensive research effort is underway to determine whether SCs that directly target CB1R, CB2R, or the enzymes that breakdown endogenous cannabinoids have anticonvulsant effects in preclinical rodent models of epilepsy and seizure. This research demonstrates that many SCs do reduce seizure severity in rodent models and may have both positive and negative pharmacodynamic and pharmacokinetic interactions with clinically used antiepilepsy drugs. Here, we provide a comprehensive review of the preclinical evidence for and against SC modulation of seizure and discuss the important questions that need to be addressed in future studies.

Early Synaptic Alterations and Selective Adhesion Signaling in Hippocampal Dendritic Zones Following Organophosphate Exposure

Organophosphates account for many of the world's deadliest poisons. They inhibit acetylcholinesterase causing cholinergic crises that lead to seizures and death, while survivors commonly experience long-term neurological problems. Here, we treated brain explants with the organophosphate compound paraoxon and uncovered a unique mechanism of neurotoxicity. Paraoxon-exposed hippocampal slice cultures exhibited progressive declines in synaptophysin, synapsin II, and PSD-95, whereas reduction in GluR1 was slower and NeuN and Nissl staining showed no indications of neuronal damage. The distinctive synaptotoxicity was observed in dendritic zones of CA1 and dentate gyrus. Interestingly, declines in synapsin II dendritic labeling correlated with increased staining for β1 integrin, a component of adhesion receptors that regulate synapse maintenance and plasticity. The paraoxon-induced β1 integrin response was targeted to synapses, and the two-fold increase in β1 integrin was selective as other synaptic adhesion molecules were unchanged. Additionally, β1 integrin-cofilin signaling was triggered by the exposure and correlations were found between the extent of synaptic decline and the level of β1 integrin responses. These findings identified organophosphate-mediated early and lasting synaptotoxicity which can explain delayed neurological dysfunction later in life. They also suggest that the interplay between synaptotoxic events and compensatory adhesion responses influences neuronal fate in exposed individuals.

Paraoxon: An Anticholinesterase That Triggers an Excitotoxic Cascade of Oxidative Stress, Adhesion Responses, and Synaptic Compromise

The anticholinesterase paraoxon (Pxn) is an organophosphate (OP) and the active metabolite of the insecticide parathion. It potently inhibits the enzyme acetylcholinesterase and leads to enhanced glutamate release, diminished GABA uptake, oxidative damage, and neurodegeneration. The resulting increased levels of acetylcholine can trigger seizures and cause neuronal and excitotoxic damage in the brain. The brain susceptibility related to anticholinesterase toxins extends beyond potential brain damage and death from toxic levels of the agent. Asymptomatic low-level exposure to such toxins can also leave the brain vulnerable or even cause it to exhibit neurological problems later in life. The actions of Pxn and similar neurotoxins have been studied in order to examine the events associated with anticholinesterase toxicity in the brain. A recent study demonstrated that Pxn exposure initiates a pathogenic cascade involving seizure events and subsequent signs of damage including unique presynaptic vulnerability and associated behavioral deficits. In addition, Pxn-mediated synaptotoxicity is also associated with enhanced production of oxidative stress as well as integrin adhesion responses. These findings provide a better understanding of the molecular events involved in Pxn toxicity.