Search Results (312)

Intracellular emetic signals involved in the cannabinoid CB₁ receptor inverse agonist/antagonist SR141716A were investigated. SR141716A (20 mg/kg, i.p.)-evoked vomiting occurred via both the central and peripheral mechanisms. This was accompanied by robust emesis-associated increases in the following: (i) c-fos- and phospho-glycogen synthase kinase-3α/β (p-GSK-3αβ)-expression in the shrew’s dorsal vagal complex (DVC), (ii) phospho-extracellular signal-regulated kinase1/2 (p-ERK_1/2) expression in both the DVC and jejunal enteric nervous system, and (iii) time-dependent upregulation of cAMP levels and phosphorylation of protein kinase A (PKA), protein kinase B (Akt), GSK-3α/β, ERK_1/2, and protein kinase C αβII (PKCαβII) in the brainstem. SR141716A-evoked emetic parameters were attenuated by diverse inhibitors of the following: PKA, ERK_1/2, GSK-3, phosphatidylinositol 3-kinase (PI3K)-Akt pathway, phospholipase C (PLC), PKC, Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), L-type Ca²⁺ channel (LTCC), store-operated Ca²⁺ entry (SOCE), inositol trisphosphate receptor (IP3R), ryanodine receptor (RyRs), both 5-HT₃-, and D_2/3-receptor antagonists, and the transient receptor potential vanilloid 1 receptor (TRPV1R) agonist. SR141716A appears to evoke vomiting via inverse agonist activity involving emesis-associated kinases, including cAMP/PKA, ERK_1/2, PI3K/Akt/GSK-3, PLC/PKCαβII, and CaMKII, which depend upon Ca²⁺ mobilization linking extracellular Ca²⁺ entry via plasma membrane Ca²⁺ channels (LTCC, SOCE, TRIPV1R) and intracellular Ca²⁺ release via IP3Rs and RyRs. The 5-HT₃, NK₁, and D_2/3 receptors also contribute to SR141716A-mediated vomiting. Full article

Background. MiR-218 is a micro-RNA expressed in two isoforms (miR-218-1 and miR-218-2) in the brain and, within the mesencephalic area, it represents a specific regulator of differentiation and functional maturation of the dopamine-releasing neurons (DAn). Deletion of miR-218 isoforms within the midbrain alters the expression of synaptic mRNAs, the neuronal excitability of DAn of the substantia nigra pars compacta (SNpc), and their ability to release dopamine (DA) within the dorsal striatum. Objectives. Here we have investigated if miR-218 impacts the function of the DAn population adjacent to SNpc, the mesencephalic ventral tegmental area (VTA) innervating the nucleus accumbens (NAcc), and the medial prefrontal cortex. Methods. With the use of miR-218-1, miR-218-2, and double conditional knock-out mice (KO1, c-KO2, c-dKO), we performed electrophysiological recordings in VTA DAn to investigate firing activity, measurements of DA release in NAcc slices by constant potential amperometry (CPA), and in vivo behavioral analysis. Results. We find that KO1 VTA neurons display hyperexcitability in comparison with c-KO2, c-dKO, and wild type (WT) neurons. DA efflux in the NAcc core and shell is reduced in all single- and double-conditional KO striatal slices in comparison with controls. The KO1 mice display a tendency toward an anxiety-like trait, as revealed by the elevated plus maze test. Conclusions. Our data indicate that miR-218-1 is the isoform that mainly regulates VTA DA neuron excitability whereas both miR-218-1 and miR-218-2 impair DA release in the mesoaccumbens pathway. Full article

Pain remains one of the most burdensome symptoms in rheumatoid arthritis (RA), often persisting despite inflammatory remission and profoundly impairing quality of life. This review aimed to evaluate the clinical efficacy and mechanistic pathways by which Janus kinase (JAK) inhibitors alleviate RA-related pain. Evidence from randomized clinical trials demonstrates that JAK inhibitors have demonstrated rapid and significant pain relief, often exceeding that of methotrexate or biologic DMARDs. Improvements in patient-reported pain scores seem to typically emerge within 1–2 weeks and are sustained over time. Beyond anti-inflammatory effects, JAK inhibitors modulate central sensitization and nociceptive signaling by attenuating IL-6 and GM-CSF activity, reducing astrocyte and microglial activation, and downregulating nociceptor excitability in dorsal root ganglia and spinal pathways. Preclinical models further suggest that JAK inhibition interrupts neuroimmune feedback loops critical to chronic pain maintenance. Comparative and network meta-analyses consistently position JAK inhibitors among the most effective agents for pain control in RA. However, individual variability in response, partly due to differential JAK-STAT activation and cytokine receptor uncoupling, underscores the need for biomarker-guided treatment approaches. JAK inhibitors represent a mechanistically distinct and clinically impactful class of therapies that target both inflammatory and non-inflammatory pain in RA. Their integration into personalized pain management strategies offers a promising path to address one of RA’s most persistent unmet needs. Full article

Objective: Molecular biology techniques were employed to investigate the effects of thrombospondin-4 (Thbs4) expression in dorsal root ganglion (DRG) on peripheral nerve injury repair and regeneration, as well as to elucidate the underlying molecular mechanisms. Methods: A sciatic nerve transection model in rat was established to analyze Thbs4 expression and localization in DRG tissues after injury. Both siRNA and adeno-associated virus (AAV) were used to knockdown or overexpress Thbs4. The effects of knockdown and overexpression of Thbs4 on axon growth were assessed using immunofluorescence staining. The roles of Thbs4 in peripheral nerve injury repair and regeneration were determined using behavioral assays, electrophysiological recordings, and transmission electron microscopy. Results: Thbs4 was primarily localized in the cell membrane and cytoplasm of DRG neurons but was also found in the intercellular spaces. In vitro experiments demonstrated that Thbs4 overexpression promoted axonal regeneration and reduced neuronal apoptosis. They also showed that Thbs4 overexpression accelerated sciatic nerve regeneration and enhanced the recovery of motor and sensory functions. Conversely, Thbs4 knockdown had the opposite effects. This study also showed that the knockdown or overexpression of Thbs4 significantly altered the expression of NF-κB and ERK signaling pathways, suggesting their involvement in peripheral nerve repair and regeneration. Conclusions: Thbs4 expression in DRG tissues is significantly altered following sciatic nerve injury. The NF-κB and ERK may be involved in regulating the repair and regeneration of the peripheral nerve by Thbs4. Full article

Neuropathic pain is a chronic condition driven by intertwined mechanisms of oxidative stress, inflammation, and cellular senescence. Nerve injury and metabolic stress elevate reactive oxygen and nitrogen species, disrupt mitochondrial function, and activate the DNA-damage response, which stabilizes p53 and induces p16/p21-mediated cell-cycle arrest. These events promote a senescence-associated secretory phenotype (SASP) rich in cytokines, chemokines, and prostanoids that amplify neuroimmune signaling. In the spinal dorsal horn and dorsal root ganglia, microglia and astroglia respond to redox imbalance and danger cues by engaging NF-κB and MAPK pathways, increasing COX-2–dependent prostaglandin synthesis, and releasing mediators such as IL-1β and BDNF that enhance synaptic transmission and reduce inhibitory tone through KCC2 dysfunction. At the periphery, persistent immune-glial cross-talk lowers activation thresholds of nociceptors and sustains ectopic firing, while impaired autophagy and mitophagy further exacerbate mitochondrial dysfunction and ROS production. Collectively, these processes establish a feed-forward loop in which redox imbalance triggers senescence programs and SASP, SASP perpetuates neuroinflammation, and neuroinflammation maintains central sensitization—thereby consolidating a self-sustaining redox–senescence–inflammatory circuit underlying neuropathic pain chronicity. Full article

Methamphetamine (METH) is an extremely addictive drug which continues to cause significant harm to individuals and communities. In the present study we trained male rats to self-administer METH for 20 days, followed by 9 days of foot shock exposure. All rats escalated their METH intake during the first 20 days. The rats that continued to self-administer METH in the presence of aversive stimuli were termed shock-resistant (SR), while those that reduced their intake were shock-sensitive (SS). RNA sequencing showed numerous differentially expressed genes (DEGs) in the prefrontal cortex, nucleus accumbens, dorsal striatum, and midbrain. Ingenuity pathway analysis linked DEGs to addiction-related mechanisms. We identified shared genes with similar expression patterns across four brain regions (SR: Fos and Ahsp; SS: Tet1, Cym, and Tmem30c). The identified genes play key roles in addiction-related brain functions, such as neuronal activity, stress response, and epigenetic regulation, and their importance in METH addiction is highlighted. These genes represent promising targets for developing new treatments aimed at reversing neuroadaptations caused by METH use. Full article

Background/Objectives: Fibromyalgia causes chronic long-term pain, with symptoms lasting for months to years. Given the lack of evidence-based methods for diagnosing and assessing fibromyalgia, it ranks among the most difficult chronic pain conditions to treat. Programmed cell death ligand 1 (PD-L1) can inhibit acute and chronic pain transmission by inhibiting neuronal ion channels. Methods: Here, we aimed to explore the analgesic efficacy and mechanism of PD-L1/PD1 in an intermittent cold stress-induced fibromyalgia pain mouse model. Results: Von Frey and Hargreaves tests were performed, showing that the mouse model exhibited mechanical (day 4: 2.08 ± 0.13 g, n = 9) and thermal hyperalgesia (day 4: 3.93 ± 0.45 s, n = 9). Electroacupuncture (EA) or intraventricular PD-L1 injection effectively alleviated the nociceptive response and led to low PD-1 levels in the mouse dorsal root ganglia, spinal cord, thalamus, somatosensory cortex, and cerebellum, as measured through Western blots. In contrast, the pain-related kinase levels increased after fibromyalgia induction; these effects were reversed by EA and PD-L1 via the inhibition of microglia/astrocytes and Toll-like receptor 4. Conclusions: Our results show that EA can treat fibromyalgia pain in mice through effects on the PD-L1/PD1 pathway, indicating its potential as a therapeutic target in fibromyalgia. Full article

Subacute combined degeneration (SCD) is a neurological disorder primarily caused by vitamin B12 deficiency. This condition leads to progressive demyelination and axonal damage, predominantly affecting the dorsal and lateral columns of the spinal cord. This review provides a comprehensive overview of SCD, detailing its complex etiology, pathophysiology, and clinical presentation. We highlight the critical role of magnetic resonance imaging (MRI) in the diagnostic process, discussing both the characteristic spinal cord findings and the more subtle intracranial abnormalities. Furthermore, we address the diagnostic challenges presented by conditions that mimic SCD in MRI, such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). We conclude by outlining current treatment pathways and identifying key areas for future research, including the use of advanced neuroimaging techniques and the potential for new therapeutic approaches. This updated synthesis aims to provide a clear framework for clinicians and researchers to better understand and manage SCD. Full article

Background/Objectives: Fibromyalgia is a chronic pain syndrome with unclear etiology, meaning that it is difficult to treat effectively. The stimulation of cannabinoid receptor 1 (CB1) suppresses neuronal excitability and synaptic transmission in nociceptive pathways via reducing activity in the calcium channel and promoting the opening of the potassium channel. Methods: In this study, we examined whether CB1 activity contributes to the antinociceptive efficacy of electroacupuncture (EA) in a mouse fibromyalgia (FM) pain model established using intermittent cold stress (ICS). The model mice demonstrated both mechanical and thermal hyperalgesia measured using the von Frey and Hargreaves tests, respectively. Results: Electroacupuncture effectively reduced both forms of hyperalgesia and enhanced CB1 expression in the dorsal root ganglia, spinal cord, hypothalamus, and periaqueductal gray. In addition, EA attenuated the fibromyalgia-associated reactive transformation of microglia and astrocytes and the activation of the pain-related TLR4–MyD88–TRAF6 signaling pathway. The effects of ICS were also mitigated by the deletion of Trpv1, the gene encoding the transient receptor potential cation channel TRPV1 (capsaicin channel) implicated in nociceptive and inflammatory signaling. Further, the antinociceptive efficacy of EA was partially recapitulated by the acupoint injection of a CB1 agonist and abolished by the injection of a CB1 antagonist, suggesting that activating CB1 is essential for this therapeutic effect. Conclusions: Electroacupuncture can effectively alleviate mechanical and thermal hyperalgesia in a mouse model affected by fibromyalgia pain by activating the CB1 pathway, highlighting the therapeutic potential of CB1 agonism as a therapeutic strategy. Full article

Parkinson’s disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, and key pathways such as neuroinflammation, oxidative stress, and autophagy are believed to significantly contribute to the mechanisms of neurodegeneration. Calpain activation plays a critical role in neuroinflammation and neurodegeneration, as demonstrated by its impact on microglial activation, reactive oxygen species (ROS) production, and neuronal survival. In this study, we investigated the effects of calpain inhibition using calpeptin (CP) and calpain-2-specific inhibitors in cellular and murine models of neuroinflammation and PD. In BV2 microglial cells, LPS-induced production of pro-inflammatory cytokines (TNF-α, IL-6) and chemokines (MCP-1, IP-10) were significantly reduced by CP treatment with a concomitant decrease in ROS generation. Similarly, in VSC-4.1 motoneuron cells, calpain inhibition attenuated IFN-γ-induced ROS production and improved cell viability, demonstrating its neuroprotective effects. Moreover, in a murine MPTP model of PD, calpain inhibition reduced astrogliosis, ROCK2 expression, and levels of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-7, and IL12p70) and chemokines (MCP-1 and IP-10) in the dorsal striatum and plasma. The specific role of calpain-2 in immune modulation was further highlighted in human microglia, SV-40 cells. With respect to immune modulation in these cells, siRNA-mediated knockdown of calpain-2, but not calpain-1, significantly reduced antigen presentation to CD4+ T cells. Thus, calpain-2 is likely involved in regulating antigen presentation and activation of inflammatory CD4+ T cells. These findings underscore the therapeutic potential of calpain-2 inhibition in mitigating neuroinflammation and neurodegeneration, particularly in PD, by targeting microglial activation, ROS production, and neuronal survival pathways. Full article

As the primary bioactive flavonoid in Coreopsis tinctoria, okanin has emerged as a promising antioxidant compound of substantial pharmacological interest. However, its efficacy against UVA-mediated photoaging remains unexplored. This research investigated the molecular mechanism underlying the photoprotective activity of okanin against UVA-mediated photoaging. Network pharmacology was employed to predict the pharmacological mechanism of Coreopsis tinctoria in skin photoaging, which was then validated through in vivo and in vitro studies. In vitro experiments indicated that treatment with okanin alleviated oxidative damage, apoptosis and mitochondrial dysfunction in HaCaT cells exposed to UVA radiation. In addition, the interaction between okanin and SIRT3 was confirmed using molecular docking, SPR and DARTS assays. However, silencing SIRT3 with siRNA abolished the promoting effects of okanin on mitophagy genes, confirming that okanin protects HaCaT cells against UVA damage through SIRT3 regulation. In in vivo, okanin enhanced the expression of SIRT3 and FOXO3a in dorsal skin, mitigating UV-mediated skin damage. Taken together, our results suggest the protective effects of okanin against UV radiation in both HaCaT cells and mice induced, at least in part, by regulating SIRT3/FOXO3a/PINK1/Parkin signaling pathway. These findings highlight the potential of okanin for use in skin care products aimed at promoting skin repair following UVA exposure. Full article

It is widely accepted that chronic inflammation constitutes a significant mechanism that promotes the biological aging process. The pineal gland is regarded as being closely related to the control of the “life clock”. The present study aimed to determine the inflammation associated with pinealectomy in the rat hippocampus and to investigate the extent to which age stage impacts the severity of this inflammation. We evaluated the expression of the Akt/NF-kB signaling pathway in neurons and gliosis level in the dorsal hippocampus (dHipp) of rats subjected to sham surgery or pinealectomy at 3, 14, or 18 months of age. The assessment was conducted using immunohistochemistry. Removal of the pineal gland resulted in significant, region-specific increases in NF-kB expression in neurons of the dHipp in the youngest and middle-aged groups. However, the change in expression of the phosphorylated form of Akt (pAkt1) in neurons went in the opposite direction in these two age groups, and there were also regional differences. Pinealectomy triggered microgliosis in both young and old rats, but middle-aged rats were resistant to microglia activation. Conversely, astrogliosis was observed in young adult and middle-aged groups with melatonin deficiency in certain regions of the dHipp. It is noteworthy that young adult rats demonstrated the highest degree of vulnerability to inflammation associated with the loss of melatonin as a hormone. In contrast, middle-aged rats with pinealectomy exhibited a complex and partial adaptive response. These findings emphasize the dynamic and age-dependent nature of neuroinflammation following pinealectomy, underscoring the developmental stage as a critical determinant of inflammatory susceptibility. Full article

Background/Objectives: The aim of this study was to explore the effects of diets with different protein levels on the metabolite composition and metabolic pathways of the longest dorsal muscle of Tibetan pigs, in order to provide a metabolic basis for optimizing the nutritional regulation strategy of Tibetan pigs. Methods: A total of 32 healthy 180-day-old depopulated male Tibetan pigs were randomly divided into four groups and fed diets with protein levels of 10%, 12%, 14%, and 16%, respectively, with a feeding cycle of 8 weeks. The longest dorsal muscle samples were collected, and their metabolic profiles were systematically analyzed by LC-MS non-targeted metabolomics. Results: The TIC plots of the quality control samples were highly overlapped, indicating a stable instrumental detection process and good consistency of sample processing. Principal component analysis and orthogonal partial least squares discriminant analysis revealed significant metabolic differences between groups with different protein levels. A total of multiple differential metabolites was obtained based on VIP value and p-value screening, and Venn diagram analysis revealed a total of 11 metabolites among the three comparative groups, suggesting that they may have key roles in the protein regulation process. Volcano plots further clarified the number and trend of significantly up- and down-regulated metabolites in each group. KEGG pathway enrichment analysis showed that, with the elevation of protein level, the metabolic pathway response showed a tendency of expanding from basal energy metabolism to the complex network of amino acid synthesis, steroidogenesis, endocrine signaling, and detoxification pathways, especially in the high-protein-treated group. Conclusions: The study showed that different protein intake levels could significantly regulate the metabolites and key metabolic pathways in the longest muscle of Tibetan pigs, which provided theoretical support for the scientific formulation of a protein supply program to optimize the quality and growth performance of Tibetan pork. Full article

Background/Objectives: Pain is a growing public health concern worldwide, and the use of combinations of drugs can improve their analgesic effects while minimizing their adverse effects. Drugs such as metformin (antidiabetic) and melatonin (sleep regulator) have analgesic potential in combination. In this study, we evaluated the pharmacological interaction between metformin and melatonin when orally administered in a rat model, using the formalin test. Methods: Female Wistar rats (220–350 g) were injected with 50 µL of 1% formalin in the dorsal surface of the right hind paw. Formalin produces pain-related flinching behavior, and antinociception was evaluated as the reduction in this response. The percentage of the antinociceptive effect was determined after the oral administration of metformin (30–1000 mg/kg), melatonin (10–150 mg/kg), and their combination (MMC). To establish the nature of the interaction, isobolographic analysis was performed in a fixed-dose ratio (0.5:0.5), based on the effective dose 50 (ED₅₀) values for each drug: metformin (947.46 ± 242.60 mg/kg) and melatonin (126.86 ± 37.98 mg/kg). To evaluate the mechanism of action, the receptor antagonist for metformin compound C (dorsomorphin) for AMPK inhibition, MT1 and MT2 melatonin receptor antagonists (4-P-PDOT, luzindole), and an opioid antagonist (naloxone) were employed. The rotarod test was used to evaluate the safety profile of the combination. Results: The metformin–melatonin combination significantly reduced the number of flinches in the second phase of the formalin test. The theoretical ED₅₀ for the combination (ED₅₀ T) was 537.15 ± 122.76 mg/kg. Experimentally, the ED₅₀ (ED₅₀ E) was significantly lower (360.83 ± 23.36 mg/kg), indicating a synergistic interaction for the combination involving opioidergic pathways, MT2 receptors, and AMPK activation. Conclusions: Oral metformin–melatonin coadministration could provide a therapeutic alternative for inflammatory pain. Full article

The evolutionary loss of ednrb2 in specific vertebrate lineages, such as mammals and cypriniform fish, raises fundamental questions about its functional necessity and potential redundancy or synergy with paralogous endothelin receptors in pigment cell development. In teleosts possessing both ednrb1a and ednrb2 (e.g., Nile tilapia), their respective and combined roles in regulating neural crest-derived pigment cell precursors remains unresolved. Using CRISPR/Cas9, we generated single and double ednrb mutants to dissect their functions. We demonstrated that ednrb1a and ednrb2 synergistically govern the differentiation and migration of iridophore precursors. While ednrb1a is broadly essential for iridophore development, ednrb2 plays a unique and indispensable role in the colonization of iridophores in the dorsal iris. Double mutants exhibit near-complete iridophore loss; severe depletion of melanophores, xanthophores, and erythrophores; and a striking, fertile, transparent phenotype. Crucially, this iridophore deficiency does not impair systemic guanine synthesis pathways. mRNA rescue experiments confirmed mitfa as a key downstream effector within the Ednrb signaling cascade. This work resolves the synergistic regulation of pigment cell fates by Ednrb receptors and establishes a mechanism for generating transparent ermplasm. Full article