Current Neuropharmacology - Volume 19, Issue 5, 2021

Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological processes at periphery and central levels, such as vascularization, inflammation, glucose homeostasis, regulation of oxidative stress and neurotransmission. BH4 de novo synthesis involves the sequential activation of three enzymes, the major controlling point being GTP cyclohydrolase I (GCH1). Complementary salvage and recycling pathways ensure that BH4 levels are tightly kept within a physiological range in the body. Even if the way of transport of BH4 and its ability to enter the brain after peripheral administration is still controversial, data showed increased levels in the brain after BH4 treatment. Available evidence shows that GCH1 expression and BH4 synthesis are stimulated by immunological factors, notably pro-inflammatory cytokines. Once produced, BH4 can act as an anti- inflammatory molecule and scavenger of free radicals protecting against oxidative stress. At the same time, BH4 is prone to autoxidation, leading to the release of superoxide radicals contributing to inflammatory processes, and to the production of BH2, an inactive form of BH4, reducing its bioavailability. Alterations in BH4 levels have been documented in many pathological situations, including Alzheimer's disease, Parkinson's disease and depression, in which increased oxidative stress, inflammation and alterations in monoaminergic function are described. This review aims at providing an update of the knowledge about metabolism and the role of BH4 in brain function, from preclinical to clinical studies, addressing some therapeutic implications.

A large body of research has shown the presence of a complex pathway of communications between the gut and the brain. It is now recognized that, through this pathway, the microbiota can influence brain homeostasis and plasticity under normal and pathological conditions. This review aims at providing an overview of preclinical and clinical pieces of evidence supporting the possible role of gut-brain axis modulation in physiological aging, in a neurodevelopmental disorder, the autism spectrum disorders and in a substance abuse disorder, the alcohol addiction. Since the normalization of gut flora can prevent changes in the behavior, we postulate that the gutbrain axis might represent a possible target for pharmacological and dietary strategies aimed at improving not only intestinal but also mental health. The present review also reports some regulatory considerations regarding the use of probiotics, illustrating the most debated issues about the possibility of considering probiotics not only as a food supplement but also as a “full” medicinal product.

Autophagy is a strictly regulated process that degrades and recycles long-lived or misfolded proteins and damaged organelles for the maintenance of energy and function homeostasis of cells. Insufficient oxygen and glucose supply caused by cerebral ischemia lead to a higher ratio of AMP/ATP, which will activate the AMPK pathway to initiate the process of autophagy. Accumulating evidence shows that autophagy participates in the pathogenesis of ischemic stroke as a double- edged sword. However, the exact role of autophagy in the pathogenesis of ischemic stroke is controversial and yet to be elucidated. In this review, the autophagy pathway, both in physiological conditions and in ischemic stroke, is expounded. The focus was also on discussing the doubleedged sword effect of autophagy in brain ischemia and its underlying mechanisms. In addition, potential therapeutic strategies for ischemic stroke targeting autophagy pathway were also reviewed.

Background: Schizophrenia is a serious mental illness that affects more than 21 million people worldwide. Both genetics and the environment play a role in its etiology and pathogenesis. Symptoms of schizophrenia are mainly categorized into positive, negative, and cognitive. One major approach to identify and understand these diverse symptoms in humans has been to study behavioral phenotypes in a range of animal models of schizophrenia. Objective: We aimed to provide a comprehensive review of the behavioral tasks commonly used for measuring schizophrenia-like behaviors in rodents together with an update of the recent study findings. Methods: Articles describing phenotypes of schizophrenia-like behaviors in various animal models were collected through a literature search in Google Scholar, PubMed, Web of Science, and Scopus, with a focus on advances over the last 10 years. Results: Numerous studies have used a range of animal models and behavioral paradigms of schizophrenia to develop antipsychotic drugs for improved therapeutics. In establishing animal models of schizophrenia, the candidate models were evaluated for schizophrenia-like behaviors using several behavioral tasks for positive, negative, and cognitive symptoms designed to verify human symptoms of schizophrenia. Such validated animal models were provided as rapid preclinical avenues for drug testing and mechanistic studies. Conclusion: Based on the most recent advances in the field, it is apparent that a myriad of behavior tests are needed to confirm and evaluate the congruency of animal models with the numerous behaviors and clinical signs exhibited by patients with schizophrenia.

Src family kinases (SFK) are a group of non-receptor tyrosine kinases which play a pivotal role in cellular responses and oncogenesis. Accumulating evidence suggest that SFK also act as a key component in signalling pathways of the central nervous system (CNS) in both physiological and pathological conditions. Despite the crucial role of SFK in signal transduction of the CNS, the relationship between SFK and molecules implicated in pain has been relatively unexplored. This article briefly reviews the recent advances uncovering the interplay of SFK with diverse membrane proteins and intracellular proteins in the CNS and the importance of SFK in the pathophysiology of migraine and neuropathic pain. Mechanisms underlying the role of SFK in these conditions and potential clinical applications of SFK inhibitors in neurological diseases are also summarised. We propose that SFK are the convergent point of signalling pathways in migraine and neuropathic pain and may constitute a promising therapeutic target for these diseases.

Alzheimer’s disease (AD) is a complex neurodegenerative disease that leads to insidious deterioration of brain functions and is considered the sixth leading cause of death in the world. Alzheimer’s patients suffer from memory loss, cognitive deficit and behavioral changes; thus, they eventually follow a low-quality life. AD is considered as a multifactorial disorder involving different neuropathological mechanisms. Recent research has identified more than 20 pathological factors that are promoting disease progression. Three significant hypotheses are said to be the root cause of disease pathology, which include acetylcholine deficit, the formation of amyloid-beta senile plaques and tau protein hyperphosphorylation. Apart from these crucial factors, pathological factors such as apolipoprotein E (APOE), glycogen synthase kinase 3β, notch signaling pathway, Wnt signaling pathway, etc., are considered to play a role in the advancement of AD and therefore could be used as targets for drug discovery and development. As of today, there is no complete cure or effective disease altering therapies for AD. The current therapy is assuring only symptomatic relief from the disease, and progressive loss of efficacy for these symptomatic treatments warrants the discovery of newer drugs by exploring these novel drug targets. A comprehensive understanding of these therapeutic targets and their neuropathological role in AD is necessary to identify novel molecules for the treatment of AD rationally.

Neurology and associated nanotherapeutics are a complex field in terms of therapeutics and neurological disorder complexity. The brain is an intricate appendage and requires more precise embattled treatment for the particular diseases and hence it is a broad scale for developing more targeted drug deliveries. The brain is one of the most inaccessible tissues of the body due to the existence of the blood-brain barrier (BBB), thus delivery of drugs inside the brain is a striking dare and it is also tricky to treat central nervous system (CNS) complications pharmacologically. The therapeutic aspiration is to accomplish the lowest drug meditation in the brain tissues so as to gain favoured therapeutic results. To devastate this obstacle, nanotechnology is engaged in the field of targeted brain drug delivery and neuropathology targeting. These carriers hold myriad abilities as they may augment the drug delivery into the brain by shielding them from degradation and prolonging their transmission in the blood, as well as promoting their transport through the BBB. Nanopharmaceuticals are quickly sprouting as a new avenue that is engaged with the drug-loaded nanocarriers to demonstrate unique physicochemical properties and tiny size range for penetrating the central nervous system. The enchantment behind their therapeutic achievement is the condensed drug dose and inferior toxicity, whereby restricting the therapeutic compound to the specific site. Therefore, in this article, we have tried to recapitulate the advances of the novel scopes for the brain targeted drug delivery for complex neurological disorders.

Background: Vortioxetine is approved for the treatment of Major Depressive Disorder (MDD). However, the safety of this drug in a large group of populations is still unclear. Thus, we have tried to analyze the risk profile of vortioxetine. Material and Methods: The data related to the risk profile of vortioxetine has been extracted from Pub-Med from January 2014 to May 2019. The adverse drug reactions (ADRs) have been categorized into listed and unlisted categories as per the Summary of product characteristics (SmPC) of the innovator. Further, unlisted ADRs have been analyzed as per Naranjo Scale. Results: Galactorrhea, hyperprolactinemia, glycolimia, exacerbation of anxiety, weight gain, edema, excessive itching, petechiae, and ecchymoses have been observed with the use of vortioxetine and falls under the unlisted category. Further, the causality assessment results have shown a probable relation between vortioxetine and galactorrhea, hyperprolactinemia, edema, excessive itching, ecchymoses, and petechiae. Weight gain, glycolimia and exacerbation of anxiety have a possible relationship with vortioxetine. The common ADRs observed with the use of vortioxetine are nausea, diarrhea, constipation, vomiting, pruritus, including pruritus generalized, abnormal dreams, and dizziness. Conclusion: In conclusion, more data is required to establish a strong relationship between vortioxetine and reported unlisted ADRs.

Background: Congenital myasthenic syndromes (CMSs) are a heterogeneous group of neuromuscular disorders. Mutations of the nicotinic acetylcholine receptor epsilon subunit gene (CHRNE) are the most common causes of these disorders. CMSs are gaining increasing recognition by clinicians. However, pharmacological treatment of CMS with CHRNE mutations has only been discussed in a small number of case reports. Objective: This study aims to determine how to choose an appropriate pharmacological strategy for CMS with CHRNE mutations. Methods: A meta-analysis was performed. PubMed, MEDLINE, Web of Science, and Cochrane Library databases were searched for studies published in English prior to June 1, 2020. The extracted data included clinical information, gene mutations, pharmacological treatment, and treatment effects. Results: A total of 48 studies and 208 CMS patients with CHRNE mutations were included in our meta-analysis. Ten different pharmacological strategies were used in these patients. Our research found that β2-adrenergic receptor agonists had the best treatment effect for CMS patients with CHRNE mutations, especially in patients with primary AChR deficiency. In addition, our analysis found no evidence that age at disease onset influences the treatment results. Conclusion: This meta-analysis provides evidence that (1) β2-adrenergic receptor agonist therapy could be the first choice of pharmacological strategy for treating CMS with CHRNE mutations; (2) a single-drug-regime, rather than a combination therapy, should be the first choice of treatment; and (3) it is never too late to initiate pharmacological treatment.