Oral acetylcysteine for neuropsychiatric disorders

Role of G-Proteins and GPCR-Mediated Signalling in Neuropathophysiology

G-protein-coupled receptors (GPCRs) are activated by manifold neurotransmitters, and their activation, in turn, evokes slow synaptic transmission. They are profoundly related to numerous psychiatric and neurological disorders such as schizophrenia and Parkinson's disease. The significant malady indications for GPCR modulators demonstrate a change towards obesity, diabetes, and Alzheimer's disease, while other central nervous system disorders persist highly represented. GPR52, GPR6, and GPR8 are recognised as orphan GPCRs, co-exist either with both the dopamine D2 and D1 receptors in neurons of the basal ganglia or with the dopamine D2 receptor alone, and recommend that between these orphan receptors, GPR52 has the maximum potential of being a therapeutic psychiatric receptor. Genetically modified creature models and molecular biological investigations have suggested that these improved GPCRs could be potential therapeutic psychiatric receptors. In this perspective, the role of molecular targets in GPCR-mediated signalling has been discussed that would be novel drug design and discovery options for a scientist to elaborate previous knowledge with modern techniques.

Insights into the Promising Prospect of G Protein and GPCR-Mediated Signaling in Neuropathophysiology and Its Therapeutic Regulation

G protein-coupled receptors (GPCRs) are intricately involved in the conversion of extracellular feedback to intracellular responses. These specialized receptors possess a crucial role in neurological and psychiatric disorders. Most nonsensory GPCRs are active in almost 90% of complex brain functions. At the time of receptor phosphorylation, a GPCR pathway is essentially activated through a G protein signaling mechanism via a G protein-coupled receptor kinase (GRK). Dopamine, an important neurotransmitter, is primarily involved in the pathophysiology of several CNS disorders; for instance, bipolar disorder, schizophrenia, Parkinson's disease, and ADHD. Since dopamine, acetylcholine, and glutamate are potent neuropharmacological targets, dopamine itself has potential therapeutic effects in several CNS disorders. GPCRs essentially regulate brain functions by modulating downstream signaling pathways. GPR6, GPR52, and GPR8 are termed orphan GPCRs because they colocalize with dopamine D1 and D2 receptors in neurons of the basal ganglia, either alone or with both receptors. Among the orphan GPCRs, the GPR52 is recognized for being an effective psychiatric receptor. Various antipsychotics like aripiprazole and quetiapine mainly target GPCRs to exert their actions. One of the most important parts of signal transduction is the regulation of G protein signaling (RGS). These substances inhibit the activation of the G protein that initiates GPCR signaling. Developing a combination of RGS inhibitors with GPCR agonists may prove to have promising therapeutic potential. Indeed, several recent studies have suggested that GPCRs represent potentially valuable therapeutic targets for various psychiatric disorders. Molecular biology and genetically modified animal model studies recommend that these enriched GPCRs may also act as potential therapeutic psychoreceptors. Neurotransmitter and neuropeptide GPCR malfunction in the frontal cortex and limbic-related regions, including the hippocampus, hypothalamus, and brainstem, is likely responsible for the complex clinical picture that includes cognitive, perceptual, emotional, and motor symptoms. G protein and GPCR-mediated signaling play a critical role in developing new treatment options for mental health issues, and this study is aimed at offering a thorough picture of that involvement. For patients who are resistant to current therapies, the development of new drugs that target GPCR signaling cascades remains an interesting possibility. These discoveries might serve as a fresh foundation for the creation of creative methods for pharmacologically useful modulation of GPCR function.

N-Acetylcysteine for the Treatment of Psychiatric Disorders: A Review of Current Evidence

N-acetylcysteine, a sulphur-containing amino acid for the treatment of paracetamol overdose and chronic obstructive pulmonary disease, is a widely available off-the-shelf oral antioxidant supplement in many countries. With the potential to modulate several neurological pathways, including glutamate dysregulation, oxidative stress, and inflammation that can be beneficial to the brain functions, N-acetylcysteine is being explored as an adjunctive therapy for many psychiatric conditions. This narrative review synthesises and presents the current evidence from systematic reviews, meta-analyses, and latest clinical trials on N-acetylcysteine for addiction and substance abuse, schizophrenia, obsessive-compulsive and related disorders, and mood disorders. Good evidence exists to support the use of N-acetylcysteine as an adjunct treatment to reduce the total and negative symptoms of schizophrenia. N-acetylcysteine also appears to be effective in reducing craving in substance use disorders, especially for the treatment of cocaine and cannabis use among young people, in addition to preventing relapse in already abstinent individuals. Effects of N-acetylcysteine on obsessive-compulsive and related disorders, as well as on mood disorders, remain unclear with mixed reviews, even though promising evidence does exist. Larger and better-designed studies are required to further investigate the clinical effectiveness of N-acetylcysteine in these areas. Oral N-acetylcysteine is safe and well tolerated without any considerable adverse effects. Current evidence supports its use as an adjunctive therapy clinically for psychiatric conditions, administered concomitantly with existing medications, with a recommended dosage between 2000 and 2400 mg/day.