CNS & Neurological Disorders - Drug Targets (Formerly Current Drug Targets - CNS & Neurological Disorders) - Volume 19, Issue 5, 2020

Autism Spectrum Disorders (ASD) is a severe childhood psychiatric condition with an array of cognitive, language and social impairments that can significantly impact family life. ASD is classically characterized by reduced communication skills and social interactions, with limitations imposed by repetitive patterns of behavior, interests, and activities. The pathophysiology of ASD is thought to arise from complex interactions between environmental and genetic factors within the context of individual development. A growing body of research has raised the possibility of identifying the aetiological causes of the disorder. This review highlights the roles of immune-inflammatory pathways, nitro-oxidative stress and mitochondrial dysfunctions in ASD pathogenesis and symptom severity. The role of NK-cells, T helper, T regulatory and B-cells, coupled with increased inflammatory cytokines, lowered levels of immune-regulatory cytokines, and increased autoantibodies and microglial activation is elucidated. It is proposed that alterations in mitochondrial activity and nitrooxidative stress are intimately associated with activated immune-inflammatory pathways. Future research should determine as to whether the mitochondria, immune-inflammatory activity and nitrooxidative stress changes in ASD affect the development of amygdala-frontal cortex interactions. A number of treatment implications may arise, including prevention-orientated prenatal interventions, treatment of pregnant women with vitamin D, and sodium butyrate. Treatments of ASD children and adults with probiotics, sodium butyrate and butyrate-inducing diets, antipurinergic therapy with suramin, melatonin, oxytocin and taurine are also discussed.

Deposition of Amyloid-beta (Aβ) peptide in the brain is the leading source of the onset and progression of Alzheimer’s Disease (AD). Recent studies have suggested that anti-amyloidogenic agents may be a suitable therapeutic strategy for AD. The current review was proposed to address the beneficial effects of cannabis-based drugs for the treatment of AD, focusing primarily on Aβ modifications. Keywords related to AD, Aβ, and cannabis-based on MeSH were identified and were searched in PubMed, Google Scholar, Scopus, Ovid-Medline, and Web of Science from inception until 15 March 2020. The full text of identified papers was obtained and assessed based on exclusion and inclusion criteria. The review is based on articles that have focused on AD and the amyloidogenic pathway. A total of 17 studies were identified based on the inclusion criteria; however, nine studies qualified for this systematic review. The maximum and minimum cannabis dosages, mostly CBD and THC in animal studies, were 0.75 and 50 mg/kg, respectively. Cannabis (CBD and THC) was injected for 10 to 21 days. The findings of the 9 articles indicated that cannabis-based drugs might modulate Aβ modifications in several AD models. Our findings establish that cannabis-based drugs inhibited the progression of AD by modulating Aβ modifications.

Migraine is a complex neurovascular disorder characterized by attacks of moderate to severe unilateral headache, accompanied by photophobia among other neurological signs. Although an arsenal of antimigraine agents is currently available in the market, not all patients respond to them. As Calcitonin Gene-Related Peptide (CGRP) plays a key role in the pathophysiology of migraine, CGRP receptor antagonists (gepants) have been developed. Unfortunately, further pharmaceutical development (for olcegepant and telcagepant) was interrupted due to pharmacokinetic issues observed during the Randomized Clinical Trials (RCT). On this basis, the use of monoclonal antibodies (mAbs; immunoglobulins) against CGRP or its receptor has recently emerged as a novel pharmacotherapy to treat migraines. RCT showed that these mAbs are effective against migraines producing fewer adverse events. Presently, the U.S. Food and Drug Administration approved four mAbs, namely: (i) erenumab; (ii) fremanezumab; (iii) galcanezumab; and (iv) eptinezumab. In general, specific antimigraine compounds exert their action in the trigeminovascular system, but the locus of action (peripheral vs. central) of the mAbs remains elusive. Since these mAbs have a molecular weight of ∼150 kDa, some studies rule out the relevance of their central actions as they seem unlikely to cross the Blood-Brain Barrier (BBB). Considering the therapeutic relevance of this new class of antimigraine compounds, the present review has attempted to summarize and discuss the current evidence on the probable sites of action of these mAbs.

Alzheimer's disease is a neuropathological disease with symptoms such as language problems, confusion as to place or time, loss of interest in activities, which were previously enjoyed, behavioral changes, and memory loss. Alzheimer's disease and other types of dementia affect almost 46.8 million people globally and are estimated to strike about 131.5 million people in 2050. It has been reported that Alzheimer's is the sixth main cause of mortality. The most used drugs, which are currently approved by the Food, and Drug Administration for Alzheimer’s disease are donepezil, rivastigmine, galantamine, memantine, and the combination of donepezil and memantine. However, most of the drugs present various adverse effects. Recently, the transdermal drug delivery route has gained increasing attention as an emerging tool for Alzheimer's disease management. Besides, transdermal drug delivery systems seem to provide hope for the management of various diseases, due to the advantages that they offer in comparison with oral dosage forms. Herein, the current advancements in transdermal studies with potent features to achieve better Alzheimer's disease management are presented. Many researchers have shown that the transdermal systems provide higher efficiency since the first-pass hepatic metabolism effect can be avoided and a prolonged drug release rate can be achieved. In summary, the transdermal administration of Alzheimer's drugs is an interesting and promising topic, which should be further elaborated and studied.

Radiotherapy is routinely used for the treatment of nearly all brain tumors, but it may lead to progressive and debilitating impairments of cognitive function. The growing evidence supports the fact that radiation exposure to CNS disrupts diverse cognitive functions including learning, memory, processing speed, attention and executive functions. The present review highlights the types of radiotherapy and the possible mechanisms of cognitive deficits and neurotoxicity following radiotherapy. The review summarizes the articles from Scopus, PubMed, and Web of science search engines. Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells, with minimal damage to healthy cells. While radiotherapy has yielded relative success in the treatment of cancer, patients are often plagued with unwanted and even debilitating side effects from the treatment, which can lead to dose reduction or even cessation of treatment. Little is known about the underlying mechanisms responsible for the development of these behavioral toxicities; however, neuroinflammation is widely considered as one of the major mechanisms responsible for radiotherapy-induced toxicities. The present study reviews the different types of radiotherapy available for the treatment of various types of cancers and their associated neurological complications. It also summarizes the doses of radiations used in the variety of radiotherapy, and their early and delayed side effects. Special emphasis is given to the effects of various types of radiations or late side effects on cognitive impairments.

Parkinson’s Disease (PD) is one of the most common neurodegenerative disorders that affects the motor system, and includes cardinal motor symptoms such as resting tremor, cogwheel rigidity, bradykinesia and postural instability. Its prevalence is increasing worldwide due to the increase in life span. Although, two centuries since the first description of the disease, no proper cure with regard to treatment strategies and control of symptoms could be reached. One of the major challenges faced by the researchers is to have a suitable research model. Rodents are the most common PD models used, but no single model can replicate the true nature of PD. In this review, we aim to discuss another animal model, the zebrafish (Danio rerio), which is gaining popularity. Zebrafish brain has all the major structures found in the mammalian brain, with neurotransmitter systems, and it also possesses a functional blood-brain barrier similar to humans. From the perspective of PD research, the zebrafish possesses the ventral diencephalon, which is thought to be homologous to the mammalian substantia nigra. We summarize the various zebrafish models available to study PD, namely chemical-induced and genetic models. The zebrafish can complement the use of other animal models for the mechanistic study of PD and help in the screening of new potential therapeutic compounds.