Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects motor and cognition functions. The etiology of Parkinson's disease remains largely unknown, but genetic and environmental factors are believed to play a role. The neurotransmitter dopamine is implicated in regulating movement, motivation, memory, and other physiological processes. In individuals with Parkinson's disease, the loss of dopaminergic neurons leads to a reduction in dopamine levels, which causes motor impairment and may also contribute to the cognitive deficits observed in some patients. Therefore, it is important to understand the pathophysiology that leads to the loss of dopaminergic neurons, along with reliable biomarkers that may help distinguish PD from other conditions, monitor its progression, or indicate a positive response to a therapeutic intervention. Important advances in the treatment, etiology, and pathogenesis of Parkinson's disease have been made in the past 50 years. Therefore, this review tries to explain the different possible mechanisms behind the depletion of dopamine in PD patients such as alpha-synuclein abnormalities, mitochondrial dysfunction, and 3,4-dihydroxyphenylacetaldehyde (DOPAL) toxicity, along with the current therapies we have and the ones that are in development. The clinical aspect of Parkinson's disease such as the manifestation of both motor and non-motor symptoms, and the differential diagnosis with similar neurodegenerative disease are also discussed.

NK cells are the major lymphocyte subset of the innate immune system that mediates antiviral and anti-tumor responses. It is well established that they develop mechanisms to distinguish self from non-self during the process of NK cell education. Unlike T and B cells, natural killer cells lack clonotypic receptors and are activated after recognizing their target via germline-encoded receptors through natural cytotoxicity, cytokine stimulation, and Ab-dependent cellular cytotoxicity. Subsequently, they utilize cytotoxic granules, death receptor ligands, and cytokines to perform their effector functions. In this review, we provide a general overview of human NK cells, as opposed to murine NK cells, discussing their ontogeny, maturation, receptor diversity, types of responses, and effector functions. Furthermore, we also describe recent advances in human NK cell biology, including tissue-resident NK cell populations, NK cell memory, and novel approaches used to target NK cells in cancer immunotherapy.

Substance use disorders (SUDs) remain a major public health challenge, with existing pharmacotherapies offering limited long-term efficacy. Traditional treatments focus on dopaminergic systems but often overlook the complex interplay between metabolic signals, neuroplasticity, and conditioned behaviors that perpetuate addiction. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), originally developed for type 2 diabetes and obesity, have recently emerged as promising modulators of reward-related brain circuits. This review synthesizes current evidence on the role of glucagon-like peptide-1 (GLP-1) and its receptor in modulating craving and substance-seeking behaviors. We highlight how GLP-1 receptors are expressed in addiction-relevant brain regions, including the ventral tegmental area (VTA), nucleus accumbens (NAc), and prefrontal cortex (PFC), where their activation influences dopaminergic, glutamatergic, and GABAergic neurotransmission. In addition, we explore how GLP-1 signaling affects reward processing through gut–brain vagal pathways, hormonal crosstalk, and neuroinflammatory mechanisms. Preclinical studies demonstrate that GLP-1RAs attenuate intake and relapse-like behavior across a range of substances, including alcohol, nicotine, and cocaine. Early-phase clinical trials support their safety and suggest potential efficacy in reducing craving. By integrating findings from molecular signaling, neurocircuitry, and behavioral models, this review provides a translational perspective on GLP-1RAs as an emerging treatment strategy in addiction medicine. We propose that targeting gut–brain metabolic signaling could provide a novel framework for understanding and treating SUDs.

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by inflammation, demyelination, and neurodegeneration within the central nervous system (CNS). It predominantly affects women and young adults, with environmental and genetic factors contributing to its onset. MS presents a wide range of neurological symptoms due to the scattering of lesions in the CNS, often leading to vision, sensorimotor, and cognitive impairments. The clinical course of MS varies, with relapsing-remitting MS (RRMS) being the most common, followed by secondary progressive MS (SPMS) and primary progressive MS (PPMS). Diagnosis is based on clinical evaluation, MRI findings, and cerebrospinal fluid analysis, with the McDonald criteria playing a key role in confirming dissemination in time and space. Current treatments, such as disease-modifying therapies (DMTs) and steroids, focus on managing relapses and reducing long-term disability. Novel therapies, including remyelination and neuroprotective agents, are showing promise in advancing care. While these medications can slow progression and improve quality of life, MS remains an incurable disease that requires ongoing research to find more effective therapies. Surgical interventions are rare but can address severe symptoms like spasticity and bladder dysfunction, contributing to an overall personalized management approach.