Search Results (114)

The limited efficacy of antipsychotics in treating the negative and cognitive symptoms of schizophrenia has prompted the exploration of adjuvant therapies. Several drugs developed for other indications—including caffeine, metformin, and furosemide—have shown procognitive potential. This study evaluated the effects of these agents on behavioral parameters using the reward-based Ambitus test, and on the cerebral D2 dopamine receptor (D2R) expression and binding. The drugs were administered individually and in combination in a schizophrenia-like triple-hit animal model (Lisket rats), derived from the Long Evans (LE) strain. Lisket rats received 14 days of drug treatment via drinking water; water-drinking LE rats served as the controls. The Ambitus test was conducted before treatment and on days 11–14. Caffeine enhanced activity without affecting learning or memory. Metformin and furosemide reduced exploratory behavior but improved reference memory; these effects were inhibited by caffeine co-administration. Although no statistically significant behavioral differences were found compared to water-treated Lisket rats, a trend toward reduced exploratory visits was observed in the triple-combination group. Lisket rats exhibited moderately reduced D2R binding in the cortex and increased binding in the hippocampus. Caffeine alone and in combination enhanced hippocampal D2R binding, while furosemide increased cortical D2R expression. This study is the first to highlight the behavioral and molecular effects of these non-antipsychotic agents in a schizophrenia model, supporting their potential for adjunctive use. Full article

Prenatal cannabis exposure (PCE) has been associated with altered prefrontal cortex (PFC) activity and connectivity in adulthood, potentially increasing the risk of psychopathology later in life. This risk is thought to involve a complex interplay between the endocannabinoid and dopaminergic systems. We investigated the transcriptional regulation of genes associated with these systems in an animal model of PCE during adolescence, focusing on DNA methylation and specific microRNAs (miRNAs). Our study revealed increased mRNA levels of dopamine D1 and D2 receptors (Drd1 and Drd2) in the PFC, with a notable effect on Drd2 in male offspring. Notably, we observed a consistent reduction in Drd2 DNA methylation levels in PCE male rats. Both Drd1 and Drd2 expressions were regulated by selective miRNAs. Accordingly, we found changes in the excitability of PFC pyramidal neurons in male adolescent PCE offspring, along with alterations in the Netrin-1/DCC guidance cue system. Our findings highlight PCE-induced modifications of the PFC dopaminergic system while maintaining stable gene expression of the endocannabinoid system in male offspring. Changes in this complex interaction during sensitive developmental periods like adolescence might lead to sex-dependent divergent behavioral outcomes induced by PCE. Full article

Objective:Burning mouth syndrome (BMS) is a chronic, intractable orofacial pain condition characterized by a burning sensation in the oral mucosa without discernible lesions. The syndrome predominantly affects menopausal and postmenopausal women and is considered a form of nociplastic pain, where the processing of pain stimuli is altered. Given the significant sex disparity, it is crucial to consider underlying neurobiological differences that may inform treatment. This review explores potential pharmacological targets by examining the pathological mechanisms of BMS. Method of Research: A narrative review approach was utilized to systematically explore and synthesize literature regarding the pathophysiology of BMS and to identify receptors implicated in the enhancement of sensory transmission and the altered processing of pain stimuli. Results: The mechanism of enhanced sensory transmission points to receptors such as TRPV1, P2X3, and CB2 as potential targets. However, considering the nociplastic nature of BMS and its prevalence in women, mechanisms involving altered central pain processing are paramount. Research indicates significant sex differences in glutamate transmission and plasticity within reward-related brain regions. This suggests that the N-methyl-D-aspartate (NMDA) receptor, a cornerstone of glutamate signaling and synaptic plasticity, is a primary therapeutic target. Furthermore, the altered processing of pain and reward, which is a key feature of chronic pain, implicates the brain’s dopaminergic system. A decrease in dopamine D2 receptor function within this system is believed to contribute to the pathology of BMS. Estrogen receptors are also considered relevant due to the menopausal onset. Conclusions: Based on the evidence, the most promising targets for pharmacotherapy in BMS are likely the NMDA receptor and the dopamine D2 receptor. The high prevalence of BMS in women, coupled with known sex differences in the glutamate and dopamine pathways of the reward system, provides a strong rationale for this focus. Effective treatment strategies should therefore aim to modulate these specific systems, directly or indirectly controlling NMDE receptor hyperactivity and addressing the decreased D2 receptor function. Further research into therapies that specifically target this sex-linked neurobiology is essential for developing effective pharmacotherapy for BMS. Full article

Geraniin (GRN), an ellagitannin from Phyllanthus urinaria, shows antioxidant, anti-inflammatory, and neuroprotective effects. This study evaluated GRN’s potential against haloperidol (HPD)-induced orofacial dyskinesia (OD). Rats treated with HPD (1 mg/kg i.p.) for 21 days exhibited dopamine D2 receptor blockade, neurotoxicity, and OD, characterized by vacuous chewing movements (VCM) and tongue protrusion (TP). Then, 60 min post-HPD, GRN was administered i.p. daily for 21 days. OD behaviors were assessed, and on Day 21, striatal tissues were analyzed for oxidative stress, mitochondrial function, inflammation, and apoptosis. GRN alone did not cause OD but significantly reduced HPD-induced VCM and TP. It also reduced oxidative stress, improved antioxidant defense, preserved mitochondrial function, and decreased neuroinflammation and apoptosis. These effects were blocked by ML385, a nuclear factor erythroid-2-related factor 2 (Nrf2) pathway inhibitor. GRN protects against HPD-induced OD, likely via Nrf2 activation. It may be a promising candidate for TD therapy, pending further clinical investigation. Full article

Dysregulated dopamine (DA) release in the mesocorticolimbic circuit is noted in Parkinson’s disease (PD) patients with impulsive and compulsive behaviors (ICBs). However, the effect of acute DA release on mood, the localization of this process, and the phenotypic differences in patients with ICB remain unknown. We applied a placebo-controlled dextro-amphetamine (dAMPH) study in 20 PD patients: 10 with ICBs (PD-ICB) and 10 without (PD-C). Subjective mood experiences were measured with well-described self-reported measures including the Positive and Negative Affect Scale (PANAS), Drug Effects Questionnaire (DEQ), and Amphetamine Interview Rating Scale (AIRS). D2-like receptor availability was measured as non-displaceable binding potential (BP_ND) using PET imaging with the high-affinity D2/3 receptor ligand [¹⁸F]-fallypride. Among all the subjects, dAMPH increased the PANAS positive, DEQ feel, DEQ high, and AIRS total scores. Increases in the PANAS positive and AIRS total scores were greater in the PD-ICB cohort. A mixed-effects model correlated these questionnaire changes with dAMPH-induced reductions in BP_ND in the ventral striatum (VS), caudate, amygdala, and caudo-medial orbitofrontal cortex. The baseline caudate, VS, and amygdala BP_ND positively correlated with lower on-dAMPH PANAS positive scores. Elevated mood symptoms of acute dAMPH administration in PD are linked to DA release in the mesocorticolimbic regions. Distinctions in behavioral effects among PD-ICB subjects emphasize that dysregulated striatal and extra-striatal DA-ergic networks alter mood responses to stimulated DA release and may also contribute to behavioral changes resulting from DA-targeting therapies in PD. Full article

Objective: To narratively review currently available antidepressants and future potential antidepressants as monotherapy for the treatment of depressive disorders. Methods: Selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), dopamine reuptake inhibitor (bupropion), tricyclic antidepressants (TCAs), and monoamine oxidase inhibitors (MAOIs) were reviewed according to the results from Sequenced Treatment Alternatives to Relieve Depression (STAR*D) Study and systematic reviews. For the rest of the antidepressants, a PubMed/Medline search was conducted with priority for systematic reviews. For drugs in development for depressive disorders, PubMed, Google, and Clinicaltrials.gov databases were used. Results: The STAR*D Study demonstrated that sertraline, venlafaxine, and bupropion monotherapy had similar efficacy in patients with major depressive disorder (MDD) who failed citalopram. A network meta-analyses of randomized, placebo-controlled trials found that SSRIs, SNRIs, bupropion, TCAs, mirtazapine, and agomelatine had similar relative efficacy compared to placebo, but had different acceptability. Gepirone had more failed/negative studies and smaller effect size relative to placebo compared to other antidepressants. The combination of dextromethorphan and bupropion, ketamine infusion, and intranasal esketamine had faster onset of action but similar effect size compared to monoamine-based antidepressants as monotherapy. Brexanolone and zuranolone are effective in postpartum depression (PPD), but the effect size of zuranolone in MDD as monotherapy or adjunctive therapy was very small. Psychedelics, glutamate receptor-related agents, kappa opioid receptor antagonists, orexin receptor antagonists, new anti-inflammatory agents, and biomarker-based antidepressant therapy have been under investigation for depressive disorders. Psychedelics showed faster onset of action, large effect size, and long durability. Conclusions: Monoamine-based antidepressants likely continue to be the mainstream antidepressants for depressive disorder. NMDA receptor antagonists and neurosteroid antidepressants will play a bigger role with the improvement of accessibility. Psychedelics may become a game changer if phase III studies validate their efficacy and safety in depressive disorders. Full article

Valerian possesses a multitude of pharmacological effects, including sedative and hypnotic properties, antihypertensive effects, antibacterial activity, and liver protection. Insomnia, one of the most prevalent disorders in contemporary society, significantly impacts people’s daily lives. This study aims to explore the anti-insomnia effects of valerian volatile oil (VVO) and investigate its potential mechanism of action through chemical analysis, network pharmacology, molecular docking, molecular dynamics simulations, and experimental validation. Through gas chromatography–mass spectrometry (GC-MS) analysis and drug-likeness screening, we identified 38 active compounds. Network pharmacology studies revealed that these 38 compounds might affect 103 targets associated with insomnia, such as monoamine oxidase B (MAOB), dopamine receptor D2 (DRD2), monoamine oxidase A (MAOA), interleukin 1β (IL1B), solute carrier family 6 member 4 (SLC6A4), prostaglandin-endoperoxide synthase 2 (PTGS2), and 5-hydroxytryptamine receptor 2A (HTR2A), which contribute to regulating the neuroactive ligand–receptor interaction, 5-hydroxytryptaminergic synapse, and calcium signaling pathways. The results of the molecular dynamics simulations indicated that bis[(6,6-dimethyl-3-bicyclo[3.1.1]hept-2-enyl)methyl] (E)-but-2-enedioate exhibited a stabilizing interaction with MAOB. The animal studies demonstrated that gavage administration of a high dose (100 mg/kg) of VVO significantly diminished autonomous activity, decreased sleep latency, and extended sleep duration in mice. Furthermore, the results of the Western blot experiment indicated that VVO interacts with MAOB, resulting in decreased expression levels of MAOB in the cerebral cortex. This study demonstrates the protective mechanism of VVO against insomnia through chemical analysis, network pharmacology, and experimental validation and extends the possible applications of VVO, which is a potential therapeutic ingredient for use in insomnia treatment. Full article

Background: Sorting nexin 19 (SNX19) is important in the localization and trafficking of the dopamine D₁ receptor (D₁R) to lipid raft microdomains. However, the interaction between SNX19 and the lipid raft components caveolin-1 or flotillin-1 and, in particular, their roles in the cellular endocytosis and cell membrane trafficking of the D₁R have not been determined. Methods: Caveolin-1 and flotillin-1 motifs were analyzed by in silico analysis; colocalization was observed by confocal immunofluorescence microscopy; protein-protein interaction was determined by co-immunoprecipitation. Results: In silico analysis revealed the presence of putative caveolin-1 and flotillin-1 binding motifs within SNX19. In mouse and human renal proximal tubule cells (RPTCs), SNX19 was localized mainly in lipid rafts. In mouse RPTCs transfected with wild-type (WT) Snx19, fenoldopam (FEN), a D₁-like receptor agonist, increased the colocalization of SNX19 with caveolin-1 and flotillin-1. FEN also increased the co-immunoprecipitation of SNX19 with caveolin-1 and flotillin-1, effects that were prevented by SCH39166, a D₁-like receptor antagonist. The FEN-mediated increase in the residence of SNX19 in lipid rafts and the colocalization of the D₁R with caveolin-1 and flotilin-1 were attenuated by the deletion of a caveolin-1 (YHTVNRRYREF) (ΔCav1) or a flotillin-1 (EEGPGTETETGLPVS) (ΔFlot1) binding motif. The FEN-mediated increase in intracellular cAMP production was also impaired by the deletion of either the flotillin-1 or caveolin-1 binding motif. Nocodazole, a microtubule depolymerization inhibitor, interfered with the FEN-mediated increase in the colocalization between SNX19 and D₁R. Conclusion: SNX19 contains caveolin-1 and flotillin-1 binding motifs, which play an important role in D₁R endocytosis and signaling. Full article

Despite recent advancements in radiotherapy for Diffuse Intrinsic Pontine Glioma (DIPG), the prognosis of this disease remains poor, highlighting the need for new treatment strategies to improve outcomes. Adding stereotactic biopsy to the diagnostic process for children with DIPG has been crucial in improving the management of this disease. Indeed, the discovery of the H3K27M mutation as a key driver of DIPG has led to the development of new drugs that are more effective than traditional ones. These include nimotuzumab (an anti-EGFR drug) and vinorelbine (a semisynthetic vinca alkaloid) in combination, Panobinostat (a histone deacetylase inhibitor), ONC201 (a drug that blocks the dopamine receptor D2 and inactivates Akt and ERK kinases), and chimeric antigen receptor (CAR) T cells. In terms of local therapy, identifying the H3K27M mutation can help us explore how genetic changes affect treatment response, recurrence patterns, and survival. Beyond the time to first recurrence, specific patterns of tumor recurrence, like leptomeningeal spread, can influence treatment plans. For example, radiotherapy can be adjusted in terms of doses and volumes, based on tumor aggressiveness. Because the H3K27M mutation is linked to higher malignancy, a slightly higher dose could be used for the second round of local irradiation. Additionally, irradiating the entire craniospinal axis could help control both local and leptomeningeal disease. Full article

Background/Objectives: Palatability significantly influences food consumption, often leading to overeating and obesity by activating the brain’s reward systems. The nucleus accumbens (NAc) plays a central role in this process, modulating reward mechanisms primarily via dopamine through D2-like receptors (D2R, D3R, D4R). While the involvement of D2 receptors in feeding is well-documented, the role of D4 receptors (D4Rs) is less clear. Methods: Male Wistar rats received intra-NAc shell microinjections of the D4R agonist PD-168077 and the antagonist L-745870. This study also examined the modulation between D4R and glutamatergic transmission by administration of NMDA, NMDA receptor antagonist AP-5, AMPA, and AMPA receptor antagonist CNQX. Results: PD-168077 increased sweet solution intake by 46%, an effect that was reversed by L-745870. Pre-treatment with NMDA prevented the stimulatory effect of PD-168077, whereas the NMDA receptor antagonist AP-5 had no such effect. Additionally, AMPA administration reduced sweet solution intake by 63%, counteracting the effect of PD-168077, while the AMPA receptor antagonist CNQX, on its own, increased intake by 40%. Conclusions: These findings suggest that D4Rs promote hedonic feeding by modulating glutamatergic transmission in the NAc shell, highlighting the complexity of D4R involvement in food intake regulation. This study underscores the potential of targeting D4Rs for therapeutic interventions in eating disorders and obesity, though further research is essential to clarify the precise mechanisms through which D4R modulates AMPA and NMDA receptor activity in feeding behavior. Full article

Pulmonary fibrosis (PF) is a severe, irreversible lung disease characterized by progressive scarring, with idiopathic pulmonary fibrosis (IPF) being the most prevalent form. IPF’s pathogenesis involves repetitive lung epithelial injury leading to fibroblast activation and excessive extracellular matrix (ECM) deposition. The prognosis for IPF is poor, with limited therapeutic options like nintedanib and pirfenidone offering only modest benefits. Emerging research highlights the dysregulation of the yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) signaling pathway as a critical factor in PF. YAP and TAZ, components of the Hippo pathway, play significant roles in cell proliferation, differentiation, and fibrosis by modulating gene expression through interactions with TEA domain (TEAD) transcription factors. The aberrant activation of YAP/TAZ in lung tissue promotes fibroblast activation and ECM accumulation. Targeting the YAP/TAZ pathway offers a promising therapeutic avenue. Preclinical studies have identified potential treatments, such as trigonelline, dopamine receptor D1 (DRD1) agonists, and statins, which inhibit YAP/TAZ activity and demonstrate antifibrotic effects. These findings underscore the importance of YAP/TAZ in PF pathogenesis and the potential of novel therapies aimed at this pathway, suggesting a new direction for improving IPF treatment outcomes. Further research is needed to validate these approaches and translate them into clinical practice. Full article

For several decades, the dopamine hypothesis contributed to the discovery of numerous typical and atypical antipsychotics and was the sole hypothesis for the pathophysiology of schizophrenia. However, neither typical nor atypical antipsychotics, other than clozapine, have been effective in addressing negative symptoms and cognitive impairments, which are indices for the prognostic and disability outcomes of schizophrenia. Following the development of atypical antipsychotics, the therapeutic targets for antipsychotics expanded beyond the blockade of dopamine D2 and serotonin 5-HT2A receptors to explore the partial agonism of the D2 receptor and the modulation of new targets, such as D3, 5-HT1A, 5-HT7, and metabotropic glutamate receptors. Despite these efforts, to date, psychiatry has not successfully developed antipsychotics with antipsychotic properties proven to be superior to those of clozapine. The glutamate hypothesis, another hypothesis regarding the pathophysiology/pathomechanism of schizophrenia, was proposed based on clinical findings that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, such as phencyclidine and ketamine, induce schizophrenia-like psychotic episodes. Large-scale genome-wide association studies (GWASs) revealed that approximately 30% of the risk genes for schizophrenia (the total number was over one hundred) encode proteins associated with glutamatergic transmission. These findings supported the validation of the glutamate hypothesis, which was inspired by the clinical findings regarding NMDAR antagonists. Additionally, these clinical and genetic findings suggest that schizophrenia is possibly a syndrome with complicated pathomechanisms that are affected by multiple biological and genetic vulnerabilities. The glutamate hypothesis has been the most extensively investigated pathophysiology/pathomechanism hypothesis, other than the dopamine hypothesis. Studies have revealed the possibility that functional abnormalities of the NMDAR play important roles in the pathophysiology/pathomechanism of schizophrenia. However, no antipsychotics derived from the glutamatergic hypothesis have yet been approved for the treatment of schizophrenia or treatment-resistant schizophrenia. Considering the increasing evidence supporting the potential pro-cognitive effects of glutamatergic agents and the lack of sufficient medications to treat the cognitive impairments associated with schizophrenia, these previous setbacks cannot preclude research into potential novel glutamate modulators. Given this background, to emphasize the importance of the dysfunction of the NMDAR in the pathomechanism and/or pathophysiology of schizophrenia, this review introduces the increasing findings on the functional abnormalities in glutamatergic transmission associated with the NMDAR. Full article

Currently, there is a growing amount of evidence for the involvement of dopamine receptors and the functionally related trace amine-associated receptor, TAAR1, in upper intestinal function. In the present study, we analyzed their expression in the duodenum using publicly accessible transcriptomic data. We revealed the expression of DRD1, DRD2, DRD4, DRD5, and TAAR1 genes in different available datasets. The results of the gene ontology (GO) enrichment analysis for DRD2 and especially TAAR1 co-expressed genes were consistent with the previously described localization of D2 and TAAR1 in enteric neurons and secretory cells, respectively. Considering that co-expressed genes are more likely to be involved in the same biological processes, we analyzed genes that are co-expressed with TAAR1, DRD2, DRD4, and DRD5 genes in healthy mucosa and duodenal samples from patients with functional dyspepsia (FD) or diabetes-associated gastrointestinal symptoms. Both pathological conditions showed a deregulation of co-expression patterns, with a high discrepancy between DRDs and TAAR1 co-expressed gene sets in normal tissues and patients’ samples and a loss of these genes’ functional similarity. Meanwhile, we discovered specific changes in co-expression patterns that may suggest the involvement of TAAR1 and D5 receptors in pathologic or compensatory processes in FD or diabetes accordingly. Despite our findings suggesting the possible role of TAAR1 and dopamine receptors in functional diseases of the upper intestine, underlying mechanisms need experimental exploration and validation. Full article

Phytocannabinoids with seven-carbon alkyl chains (phorols) have gained a lot of attention, as they are commonly believed to be more potent versions of typical cannabinoids with shorter alkyl chains. At the time of this article, cannabidiphorol (CBDP) and tetrahydrocannabiphorol (THCP) can both be purchased in the North American market, even though their biological activities are nearly unknown. To investigate their relative potency, we conducted in vitro receptor-binding experiments with CBDP (cannabinoid CB1/CB2 receptor antagonism, serotonin 5HT-1A agonism, dopamine D2S (short form) agonism, and mu-opioid negative allosteric modulation) and compared the observed activity with that of CBD. To our knowledge, this is the first publication to investigate CBDP’s receptor activity in vitro. A similar activity profile was observed for both CBD and CBDP, with the only notable difference at the CB2 receptor. Contrary to common expectations, CBD was found to be a slightly more potent CB2 antagonist than CBDP (p < 0.05). At the highest tested concentration, CBD demonstrated antagonist activity with a 33% maximum response of SR144528 (selective CB2 antagonist/inverse agonist). CBDP at the same concentration produced a weaker antagonist activity. A radioligand binding assay revealed that among cannabinoid and serotonin receptors, CB2 is likely the main biological target of CBDP. However, both CBD and CBDP were found to be significantly less potent than SR144528. The interaction of CBDP with the mu-opioid receptor (MOR) produced unexpected results. Although the cannabidiol family is considered to be a set of negative allosteric modulators (NAMs) of opioid receptors, we observed a significant increase in met-enkephalin-induced mu-opioid internalization when cells were incubated with 3 µM of CBDP and 1 µM met-enkephalin, a type of activity expected from positive allosteric modulators (PAMs). To provide a structural explanation for the observed PAM effect, we conducted molecular docking simulations. These simulations revealed the co-binding potential of CBDP (or CBD) and met-enkephalin to the MOR. Full article

Chronic migraine is a disabling disorder without effective therapeutic medicine. AMPA receptors have been proven to be essential to pathological pain and headaches, but the related regulatory mechanisms in chronic migraine have not yet been explored. In this study, we found that the level of surface GluA2 was reduced in chronic migraine rats. Tat-GluR23Y (a GluA2 endocytosis inhibitor) reduced calcium inward flow and weakened synaptic structures, thus alleviating migraine-like pain sensitization. In addition, the inhibition of GluA2 endocytosis reduced the calcium influx and alleviated mitochondrial calcium overload and ROS generation in primary neurons. Furthermore, our results showed that ROS can induce allodynia and GluA2 endocytosis in rats, thus promoting migraine-like pain sensitization. In our previous study, the dopamine D2 receptor was identified as a potential target in the treatment of chronic migraine, and here we found that dopamine D2 receptor activation suppressed chronic-migraine-related pain sensitization through blocking the GluA2/ROS positive feedback loop in vivo and in vitro. Additionally, ligustrazine, a core component of ligusticum chuanxiong, was shown to target the dopamine D2 receptor, thereby alleviating ROS production and abnormal nociception in CM rats. This study provides valuable insight into the treatment of chronic migraine. Full article