Abstract:Objective Functional near-infrared spectroscopy (fNIRS), a novel non-invasive technique for monitoring cerebral activity, can be integrated with upper limb rehabilitation robots to facilitate the real-time assessment of neurological rehabilitation outcomes. The rehabilitation robot is designed with 3 training modes: passive, active, and resistance. Among these, the resistance mode has been demonstrated to yield superior rehabilitative outcomes for patients with a certain level of muscle strength. The control modes in the resistance mode can be categorized into dynamic and static control. However, the effects of different control modes in the resistance mode on the motor function of patients with upper limb hemiplegia in stroke remain unclear. Furthermore, the effects of force, an important parameter of different control modes, on the activation of brain regions have rarely been reported .This study investigates the effects of dynamic and static resistance modes under varying resistance levels on cerebral functional alterations during motor rehabilitation in post-stroke patients.Methods A cohort of 20 stroke patients with upper limb dysfunction was enrolled in the study, completing preparatory adaptive training followed by 3 intensity-level tasks across 2 motor paradigms. The bilateral prefrontal cortices (PFC), bilateral primary motor cortices (M1), bilateral primary somatosensory cortices (S1), and bilateral premotor and supplementary motor cortices (PM) were examined in both the resting and motor training states. The Lateralization index (LI), phase locking value (PLV), network metrics were employed to examine cortical activation patterns and topological properties of brain connectivity.Results The data indicated that both dynamic and static modes resulted in significantly greater activation of the contralateral M1 area and the ipsilateral PM area when compared to the resting state. The static patterns demonstrated a more pronounced activation in the contralateral M1 in comparison to the dynamic patterns. The results of brain network analysis revealed significant differences between the dynamic and resting states in the contralateral PFC area and contralateral M1 area (F=4.709, P=0.038), as well as in the contralateral PM area and ipsilateral M1 area (F=4.218, P=0.049). Moreover, the findings indicated a positive correlation between the activation of the M1 region and the increase in force in the dynamic mode, which was reversed in the static mode.Conclusion Both dynamic and static resistance training modes have been demonstrated to activate the corresponding brain functional regions. Dynamic resistance modes elicit greater oxygen changes and connectivity to the region of interest (ROI) than static resistance modes. Furthermore, the effects of increasing force differ between the two modes. In patients who have suffered a stroke, dynamic modes may have a more pronounced effect on the activation of exercise-related functional brain regions.

Abstract:Self-face is a unique and highly distinctive stimulus, not shared with others, and serves as a reliable marker of self-awareness. Compared to other faces, self-face processing exhibits several advantages, including the self-face recognition advantage, self-face attention advantage, and self-face positive processing advantage. The self-face recognition advantage manifests as faster and more accurate identification across different orientations and spatial frequency components, supported by enhanced early event-related potential (ERP) components, such as N170. Attentional biases toward self-face are evident in target detection during spatial tasks and the attentional blink effect in temporal paradigms. However, measurement sensitivity, perceptual load, and task demands contribute to some mixed findings. Positive biases further characterize the self-face processing advantage, with individuals perceiving their faces as more attractive or trustworthy than objective representations. These biases even extend to self-similar others, influencing social behaviors such as trust and voting preferences. Self-face processing advantages have been observed at an unconscious level and are regulated by several factors, including self-esteem, cultural differences, and multisensory integration. Cultural and individual differences play a crucial role in shaping self-face advantages. Individuals from Western cultures, which emphasize independent self-construal, exhibit stronger self-face biases compared to those from East Asian collectivist contexts. Self-esteem also modulates self-face advantages: High-self-esteem individuals generally maintain their self-face recognition advantage despite interference, exhibit attentional prioritization of self-faces, and demonstrate enhanced positive associations with subliminal self-faces. In contrast, low-self-esteem individuals display recognition vulnerabilities to social cues, show context-dependent attentional divergence (prioritizing others" faces in task-oriented settings while prioritizing self-face in free-viewing tasks), and exhibit reversed positive associations with subliminal self-faces. Multisensory integration, such as synchronized visual-tactile cues, enhances self-face advantages and induces perceptual plasticity. This phenomenon is exemplified by the enfacement illusion, in which synchronous visual and tactile inputs update the mental representation of the self-face, leading to assimilation with another face. Neuroanatomically, self-face processing is predominantly lateralized to the right hemisphere and involves a network of brain regions, including the occipital lobe, temporal lobe, frontal lobe, insula, and cingulate gyrus. Disruptions in these networks are linked to self-face processing deficits in socio-cognitive disorders. For instance, autism spectrum disorder (ASD) and schizophrenia are associated with attenuated self-face advantages and abnormal neural activity in regions such as the right inferior frontal gyrus, insula, and posterior cingulate cortex. These findings suggest that self-face processing could serve as a potential biomarker for the early diagnosis and intervention of such disorders. In recent years, researchers have proposed various theoretical explanations for self-face processing and its advantage effects. However, some studies have reported no significant behavioral or neural advantages of self-faces over familiar faces, leaving the specificity of self-face a subject of debate. Further elucidation of self-face specificity requires the adoption of a face association paradigm, which controls for facial familiarity and helps determine whether qualitative differences exist between self-faces and familiar faces. Given the close relationship between self-face processing advantages and socio-cognitive disorders (e.g., ASD, schizophrenia), a deeper understanding of self-face specificity has the potential to provide critical insights into the early identification, classification, and intervention of these disorders. This research holds both theoretical significance and substantial social value.

Abstract:Postmenopausal osteoporosis (PMOP) is a chronic metabolic bone disease caused by a decrease in estrogen levels. with the acceleration of population aging process, the public health burden caused by it is becoming increasingly severe. The prevalence rate of osteoporosis in people over 65 years old in China is as high as 32%, which is especially prominent after menopause, which is about 5 times that of elderly men. About 40% of postmenopausal women are at risk of osteoporotic fractures, with a disability rate of up to 50% and a fatality rate of about 20%. The prevention and treatment of osteoporosis has become a major public health issue of global concern, and it is particularly urgent to develop reasonable and effective prevention and treatment programs and explore their scientific basis. Exercise is an important non-drug means for the prevention and treatment of PMOP, it can improve estrogen levels and the expression of bone formation transcription factors, and inhibit the levels of proinflammatory factors and bone resorption markers, macroscopically manifested by the improvement of bone microstructure and bone density. However, the effectiveness of exercise in improving bone mineral density (BMD) remains controversial. Some studies revealed significant changes of bone to mechanical stimulation, while others showed no significant effect of mechanical training, this heterogeneity in bone adapt to mechanical stimulation is particularly evident in postmenopausal women. Although the evidence that a wide range of exercise programs can improve osteoporosis, the optimal solution to address bone mineral loss remains unclear. The most effective exercise type, dosage and personalized adaptation are still being determined. This study will fully consider the differences in gender and hormone levels, searching and screening randomized controlled trials of PubMed, CNKI and other databases regarding exercise improving bone mineral density in women with PMOP. Strictly following the PRISMA guidelines to reviewed and compared the effects of different types of exercise modalities on BMD at different sites in women with PMOP by network Meta-analysis, to provide theoretical guidance to maintain or improve BMD in women with PMOP.

Abstract:Mitochondria, the primary energy-producing organelles of the cell, also serve as signaling hubs and participate in diverse physiological and pathological processes, including apoptosis, inflammation, oxidative stress, neurodegeneration, and tumorigenesis. As semi-autonomous organelles, mitochondrial functionality relies on nuclear support, with mitochondrial biogenesis and homeostasis being stringently regulated by the nuclear genome. This interdependency forms a bidirectional signaling network that coordinates cellular energy metabolism, gene expression, and functional states. During mitochondrial damage or dysfunction, retrograde signals are transmitted to the nucleus, activating adaptive transcriptional programs that modulate nuclear transcription factors, reshape nuclear gene expression, and reprogram cellular metabolism. This mitochondrion-to-nucleus communication, termed "mitochondrial retrograde signaling", fundamentally represents a mitochondrial "request" to the nucleus to maintain organellar health, rooted in the semi-autonomous nature of mitochondria. Despite possessing their own genome, the "fragmented" mitochondrial genome necessitates reliance on nuclear regulation. This genomic incompleteness enables mitochondria to sense and respond to cellular and environmental stressors, generating signals that modulate the functions of other organelles, including the nucleus. Evolutionary transfer of mitochondrial genes to the nuclear genome has established mitochondrial control over nuclear activities via retrograde communication. When mitochondrial dysfunction or environmental stress compromises cellular demands, mitochondria issue retrograde signals to solicit nuclear support. Studies demonstrate that mitochondrial retrograde signaling pathways operate in pathological contexts such as oxidative stress, electron transport chain (ETC) impairment, apoptosis, autophagy, vascular tension, and inflammatory responses. Mitochondria-related diseases exhibit marked heterogeneity but invariably result in energy deficits, preferentially affecting high-energy-demand tissues like muscles and the nervous system. Consequently, mitochondrial dysfunction underlies myopathies, neurodegenerative disorders, metabolic diseases, and malignancies. Dysregulated retrograde signaling triggers proliferative and metabolic reprogramming, driving pathological cascades. Mitochondrial retrograde signaling critically influences tumorigenesis and progression. Tumor cells with mitochondrial dysfunction exhibit compensatory upregulation of mitochondrial biogenesis, excessive superoxide production, and ETC overload, collectively promoting metastatic tumor development. Recent studies reveal that mitochondrial retrograde signaling—mediated by altered metabolite levels or stress signals—induces epigenetic modifications and is intricately linked to tumor initiation, malignant progression, and therapeutic resistance. For instance, mitochondrial dysfunction promotes oncogenesis through mechanisms such as epigenetic dysregulation, accumulation of mitochondrial metabolic intermediates, and mitochondrial DNA (mtDNA) release, which activates the cytosolic cGAS-STING signaling pathway. In normal cells, miR-663 mediates mitochondrion-to-nucleus retrograde signaling under reactive oxygen species (ROS) regulation. Mitochondria modulate miR-663 promoter methylation, which governs the expression and supercomplex stability of nuclear-encoded oxidative phosphorylation (OXPHOS) subunits and assembly factors. However, dysfunctional mitochondria induce oxidative stress, elevate methyltransferase activity, and cause miR-663 promoter hypermethylation, suppressing miR-663 expression. Mitochondrial dysfunction also triggers retrograde signaling in primary mitochondrial diseases and contributes to neurodegenerative disorders such as Parkinson"s disease (PD) and Alzheimer"s disease (AD). Current therapeutic strategies targeting mitochondria in neurological diseases focus on 5 main approaches: alleviating oxidative stress, inhibiting mitochondrial fission, enhancing mitochondrial biogenesis, mitochondrial protection, and insulin sensitization. In AD patients, mitochondrial morphological abnormalities and enzymatic defects, such as reduced pyruvate dehydrogenase and α-ketoglutarate dehydrogenase activity, are observed. Platelets and brains of AD patients exhibit diminished cytochrome c oxidase (COX) activity, correlating with mitochondrial dysfunction. To model AD-associated mitochondrial pathology, researchers employ cybrid technology, transferring mtDNA from AD patients into enucleated cells. These cybrids recapitulate AD-related mitochondrial phenotypes, including reduced COX activity, elevated ROS production, oxidative stress markers, disrupted calcium homeostasis, activated stress signaling pathways, diminished mitochondrial membrane potential, apoptotic pathway activation, and increased Aβ42 levels. Furthermore, studies indicate that Aβ aggregates in AD and α-synuclein aggregates in PD trigger mtDNA release from damaged microglial mitochondria, activating the cGAS-STING pathway. This induces a reactive microglial transcriptional state, exacerbating neurodegeneration and cognitive decline. Targeting the cGAS-STING pathway may yield novel therapeutics for neurodegenerative diseases like AD, though translation from bench to bedside remains challenging. Such research not only deepens our understanding of disease mechanisms but also informs future therapeutic strategies. Investigating the triggers, core molecular pathways, and regulatory networks of mitochondrial retrograde signaling advances our comprehension of intracellular communication and unveils novel pathogenic mechanisms underlying malignancies, neurodegenerative diseases, and type 2 diabetes mellitus. This review summarizes established mitochondrial-nuclear retrograde signaling axes, their roles in interorganellar crosstalk, and pathological consequences of dysregulated communication. Targeted modulation of key molecules and proteins within these signaling networks may provide innovative therapeutic avenues for these diseases.

Abstract:Biomolecular condensates are formed through phase separation of biomacromolecules such as proteins and RNAs. These condensates exhibit liquid-like properties that can futher transition into more stable material states. They form complex internal structures via multivalent weak interactions, enabling precise spatiotemporal regulations. However, the use of inconsistent and non-standardized terminology has become increasingly problematic, hindering academic exchange and the dissemination of scientific knowledge. Therefore, it is necessary to discuss the terminology related to biomolecular condensates in order to clarify concepts, promote interdisciplinary cooperation, enhance research efficiency, and support the healthy development of this field.

Abstract:Radiation-induced injury is a key factor in determining the prognosis of patients undergoing radiotherapy, highlighting the significant clinical importance of developing drugs for radiation prevention and treatment. Especially in oncology, radiation-induced injury remains a pivotal determinant of therapeutic outcomes, because of its direct correlation with normal tissue damage during radiotherapy. Efforts to mitigate or treat such injury are thus paramount in enhancing the overall safety and efficacy of cancer treatment. Novel nanomedicines with prolonged systemic circulation, versatile drug-loading capacities, enhanced tissue retention, and stimuli responsiveness exhibit unique advantages in the treatment and prevention of radiation-induced diseases, as they can be designed based on the specific microenvironment of radiation-damaged tissues, which offers innovative solutions to address the limitations of conventional radioprotectors such as short half-life, poor tissue targeting, and systemic side effects. This review thus aims to provide an overview of recent advance in the design and application of nanomaterials for radiation prevention and treatment. Generally, ionizing radiation damages cells either by inducing DNA double-strand breaks or through the generation of reactive oxygen species (ROS). The resulting oxidative stress would disrupt the structural integrity of cell membranes, proteins, and nucleic acids, leading to apoptosis, chronic inflammation, and systemic effects across multiple systems, including hematopoietic system, gastrointestinal tract, skin, lungs, brain, and heart. Radiation protection strategies focus on scavenging ROS, stimulating cellular repair and regeneration, inducing tissue hypoxia, and inhibiting apoptotic pathways. Recent advances in nanomedicine have introduced novel approaches for targeted and efficient radiation protection and treatment. For radiation-induced hematopoietic injury, nanoparticles can been designed to promote red and white blood cell regeneration while reducing oxidative stress. To address radiation-induced gastrointestinal injuries, nanomaterials enable localized antioxidant delivery and extended intestinal retention, effectively relieving radiation enteritis by scavenging ROS and modulating gut microbiota. For radiation-induced skin injuries, self-assembling peptide hydrogels that mimic the extracellular matrix can serve as effective scaffolds for wound healing. These hydrogels exhibit excellent antioxidant properties, stimulating angiogenesis, and accelerating the recovery of radiation dermatitis. In cases of radiation-induced brain damage, nanoparticles were designed to cross the blood-brain barrier to rescue neuronal damage and protect cognitive function. This review provides an in-depth insight into the mechanisms underlying radiation-induced injuries and highlights how nanomaterial were construtced according to the specific injury. Therefore, nanotechnology endowers durgs with transformative potential for preventing and treating radiation-induced injuries. Despite significant progress in nanomedicine, there are still challenges in long-term biocompatibility, precise targeting of damaged tissues, and scalable manufacturing. In addition, an in-depth understanding of the interactions between nanomaterials and biological systems remains to be covered. Future efforts should focus on optimizing design strategies, enhancing clinical translatability, and ensuring long-term safety, ultimately improving patient outcomes. Besides, expanding research into other radiation-induced diseases, such as radiation-induced ophthalmic disorders and hepatic injuries, may diversify therapeutic options.

Abstract:The liver, skeletal muscle, and adipose tissue are central energy-metabolizing organs and insulin-sensitive tissues, playing a crucial role in maintaining glucose homeostasis. As the powerhouse of the cell, mitochondria not only regulate insulin secretion but also oversee the oxidative phosphorylation and β-oxidation of fatty acids, processes vital for the metabolism of carbohydrates and fats, as well as the synthesis of ATP. The mitochondrial quality control system is of paramount importance for sustaining mitochondrial homeostasis, achieved through mechanisms such as protein homeostasis, mitochondrial dynamics, mitophagy, and biogenesis. Evidence suggests that dysfunctional mitochondria may significantly contribute to insulin resistance and ectopic fat storage in the liver, offering new insights into the strong correlation between mitochondrial dysfunction and the development of obesity, diabetes mellitus type 2 (T2DM), and non-alcoholic fatty liver disease (NAFLD). This manuscript aims to delve into the precise mechanisms by which imbalances in mitochondrial quality control lead to metabolic disorders in the liver, skeletal muscle, and adipose tissue, the 3 major insulin-sensitive organs. In the liver, mitochondrial dysfunction can lead to disturbances in glucose and lipid metabolism, resulting in insulin resistance and fat accumulation—a key factor in the development of NAFLD. In skeletal muscle, reduced mitochondrial function can decrease ATP production, weakening the muscle’s ability to uptake glucose, thereby exacerbating insulin resistance. In adipose tissue, mitochondrial dysfunction can impair adipocyte function, leading to lipotoxicity and inflammatory responses,which further contribute to insulin resistance and the onset of metabolic syndrome. Moreover, the interorgan crosstalk among these 3 tissues is essential for overall metabolic homeostasis. For instance, hepatic gluconeogenesis and glucose utilization in skeletal muscle are both influenced by the health status of their respective mitochondrial populations. The conversion between different types of adipose tissue and the ability to store lipids depend on normal mitochondrial function to avert ectopic fat accumulation in other organs. In summary, this manuscript emphasizes the critical role of mitochondrial quality control in maintaining the metabolic stability of the liver, skeletal muscle, and adipose tissue. It elucidates the specific mechanisms by which mitochondrial dysfunction in these organs contributes to the development of metabolic diseases, providing a foundation for future research and the development of therapeutic strategies targeting mitochondrial dysfunction.

Abstract:Mitochondria play a pivotal role in spermatogenesis and sperm activation in Caenorhabditis elegans, serving as the primary ATP supplier for cell division and differentiation while also acting as a key regulator of zinc ion homeostasis, membrane dynamics, and apoptotic signaling. This review systematically summarizes the essential mitochondrial mechanisms at different stages of sperm development, highlighting their multifaceted contributions beyond energy metabolism. Mitochondria are crucial for maintaining the health and stability of the gonads by regulating key apoptotic execution proteins that facilitate the proper elimination of damaged or unnecessary germ cells. Additionally, mitochondria dynamically adjust their energy supply to meet the metabolic demands of different stages of germline development. During early spermatogenesis, mitochondria provide ATP to fuel mitotic and meiotic divisions, support cellular differentiation, and regulate H⁺ and Zn²⁺ exchange to maintain cytoplasmic homeostasis, thereby ensuring the proper maturation and functionality of sperm cells. As spermatogenesis progresses, mitochondria participate in processing and sorting essential sperm proteins, such as major sperm protein (MSP), and contribute to the formation of membranous organelles (MOs), which are critical for subsequent activation events. During sperm activation, mitochondria play a dual role in ensuring a successful transition from immotile spermatids to fully functional spermatozoa. First, they provide ATP to facilitate pseudopod formation, MO fusion, and ion channel regulation, all of which are essential for sperm motility and fertilization potential. Second, mitochondria regulate the quality and quantity of functional mitochondria within sperm cells through mitopherogenesis—a recently discovered process in which mitochondrial vesicles are selectively released, ensuring that only healthy mitochondria are retained. This quality-control mechanism optimizes mitochondrial function, which is crucial for sustaining sperm motility and longevity. Beyond their traditional role in energy metabolism, mitochondria may also contribute to protein synthesis during spermatogenesis and activation. Recent evidence suggests that mitochondrial ribosomes actively translate specific proteins required for sperm function, challenging the long-standing belief that spermatozoa do not engage in de novo protein synthesis after differentiation. This emerging perspective raises important questions about the role of mitochondria in regulating sperm activation at the molecular level, particularly in modulating oxidative phosphorylation (OXPHOS) protein composition to optimize ATP production. In summary, mitochondria serve as both the central energy hub and a crucial regulatory factor in sperm activation, metabolic homeostasis, and reproductive success. Their involvement extends beyond ATP generation to include apoptotic regulation, ion homeostasis, vesicle-mediated mitochondrial quality control, and potential contributions to protein synthesis. Understanding these mitochondrial functions in C. elegans not only deepens our knowledge of nematode reproductive biology, but also provides valuable insights into broader mechanisms governing mitochondrial regulation in germline cells across species. These findings open new avenues for future research into the interplay between mitochondria, energy metabolism, and sperm function, with potential implications for reproductive health and fertility studies.

Abstract:Locomotion, a fundamental motor function encompassing various forms such as swimming, walking, running, and flying, is essential for animal survival and adaptation. The mesencephalic locomotor region (MLR), located at the midbrain-hindbrain junction, is a conserved brain area critical for controlling locomotion. This review highlights recent advances in understanding the MLR"s structure and function across species, from lampreys to mammals and birds, with a particular focus on insights gained from optogenetic studies in mammals. The goal is to uncover universal strategies for MLR-mediated locomotor control. Electrical stimulation of the MLR in species such as lampreys, salamanders, cats, and mice initiates locomotion and modulates speed and patterns. For example, in lampreys, MLR stimulation induces swimming, with increased intensity or frequency enhancing propulsive force. Similarly, in salamanders, graded stimulation transitions locomotor outputs from walking to swimming. Histochemical studies reveal that effective MLR stimulation sites colocalize with cholinergic neurons, suggesting a conserved neurochemical basis for locomotion control. In mammals, the MLR comprises two key nuclei: the cuneiform nucleus (CnF) and the pedunculopontine nucleus (PPN). Both nuclei contain glutamatergic and GABAergic neurons, with the PPN additionally housing cholinergic neurons. Optogenetic studies in mice by selectively activating glutamatergic neurons have demonstrated that the CnF and PPN play distinct roles in motor control: the CnF drives rapid escape behaviors, while the PPN regulates slower, exploratory movements. This functional specialization within the MLR allows animals to adapt their locomotion patterns and speed in response to environmental demands and behavioral objectives. Similar to findings in lampreys, the CnF and PPN in mice transmit motor commands to spinal effector circuits by modulating the activity of brainstem reticular formation neurons. However, they achieve this through distinct reticulospinal pathways, enabling the generation of specific behaviors. Further insights from monosynaptic rabies viral tracing reveal that the CnF and PPN integrate inputs from diverse brain regions to produce context-appropriate behaviors. For instance, glutamatergic neurons in the PPN receive signals from other midbrain structures, the basal ganglia, and medullary nuclei, whereas glutamatergic neurons in the CnF rarely receive inputs from the basal ganglia but instead are strongly influenced by the periaqueductal grey and inferior colliculus within the midbrain. These differential connectivity patterns underscore the specialized roles of the CnF and PPN in motor control, highlighting their unique contributions to coordinating locomotion. Birds exhibit exceptional flight capabilities, yet the avian MLR remains poorly understood. Comparative studies suggest that the pedunculopontine tegmental nucleus (PPTg) in birds is homologous to the mammalian PPN, which contains cholinergic neurons, while the intercollicular nucleus (ICo) or nucleus isthmi pars magnocellularis (ImC) may correspond to the CnF. These findings provide important clues for identifying the avian MLR and elucidating its role in flight control. However, functional validation through targeted experiments is urgently needed to confirm these hypotheses. Optogenetics and other advanced techniques in mice have greatly advanced MLR research, enabling precise manipulation of specific neuronal populations. Future studies should extend these methods to other species, particularly birds, to explore unique locomotor adaptations. Comparative analyses of MLR structure and function across species will deepen our understanding of the conserved and evolved features of motor control, revealing fundamental principles of locomotion regulation throughout evolution. By integrating findings from diverse species, we can uncover how the MLR has been adapted to meet the locomotor demands of different environments, from aquatic to aerial habitats.

Abstract:In recent years, the prevalence of diabetes has continued to rise, with diabetes mellitus type 2 being the most common form. Diabetes mellitus type 2 is characterized by chronic low-grade inflammation and disruptions in insulin metabolism. Toll-like receptor 4 (TLR4) is a key pattern recognition receptor that, upon activation, upregulates pro-inflammatory cytokines via the nuclear factor κB (NF-κB) pathway, thereby contributing to the pathogenesis of diabetes mellitus type 2. Peripheral 5-hydroxytryptamine (5-HT), primarily synthesized by enterochromaffin (EC) cells in the gut, interacts with 5-hydroxytryptamine receptors (5-HTRs) in key insulin-target tissues, including the liver, adipose tissue, and skeletal muscle. This interaction influences hepatic gluconeogenesis, fat mobilization, and the browning of white adipose tissue. Elevated peripheral 5-HT levels may disrupt glucose and lipid metabolism, thereby contributing to the onset and progression of diabetes mellitus type 2. Within mitochondria, 5-HT undergoes degradation and inactivation through the enzymatic action of monoamine oxidase A (MAO-A), leading to the generation of reactive oxygen species (ROS). Excessive ROS production and accumulation can induce oxidative stress, which may further contribute to the pathogenesis of diabetes mellitus type 2. Platelets serve as the primary reservoir for 5-HT in the bloodstream. The activation of the TLR4 signaling pathway on the platelet surface, coupled with reduced expression of the 5-HT transporter on the cell membrane, leads to elevated serum 5-HT levels, potentially accelerating the progression of diabetes mellitus type 2. Therefore, inhibition of TLR4 and reduction of peripheral 5-HT levels could represent promising therapeutic strategies for diabetes mellitus type 2. This review explores the synthesis, transport, and metabolism of peripheral 5-HT, as well as its role in TLR4-mediated diabetes mellitus type 2, with the aim of providing novel insights into the clinical diagnosis, treatment, and evaluation of diabetes mellitus type 2.