Impact of miR-29c-3p in the Nucleus Accumbens on Methamphetamine-Induced Behavioral Sensitization and Neuroplasticity-Related Proteins.

Methamphetamine (METH) abuse inflicts both physical and psychological harm. While our previous research has established the regulatory role of miR-29c-3p in behavior sensitization, the underlying mechanisms and target genes remain incompletely understood. In this study, we employed the isobaric tags for relative and absolute quantitation (iTRAQ) technique in conjunction with Ingenuity pathway analysis (IPA) to probe the putative molecular mechanisms of METH sensitization through miR-29c-3p inhibition. Through a microinjection of AAV-anti-miR-29c-3p into the nucleus accumbens (NAc) of mice, we observed the attenuation of METH-induced locomotor effects. Subsequent iTRAQ analysis identified 70 differentially expressed proteins (DEPs), with 22 up-regulated potential target proteins identified through miR-29c-3p target gene prediction and IPA analysis. Our focus extended to the number of neuronal branches, the excitatory synapse count, and locomotion-related pathways. Notably, GPR37, NPC1, and IREB2 emerged as potential target molecules for miR-29c-3p regulation, suggesting their involvement in the modulation of METH sensitization. Quantitative PCR confirmed the METH-induced aberrant expression of Gpr37, Npc1, and Ireb2 in the NAc of mice. Specifically, the over-expression of miR-29c-3p led to a significant reduction in the mRNA level of Gpr37, while the inhibition of miR-29c-3p resulted in a significant increase in the mRNA level of Gpr37, consistent with the regulatory principle of miRNAs modulating target gene expression. This suggests that miR-29c-3p potentially influences METH sensitization through its regulation of neuroplasticity. Our research indicates that miR-29c-3p plays a crucial role in regulating METH-induced sensitization, and it identified the potential molecular of miR-29c-3p in regulating METH-induced sensitization.

Genomic Features and Comparative Genomic Analysis of Streptococcus sp. v1. nov., Isolated from an Endophthalmitis Patient.

Endophthalmitis is an acute inflammatory intraocular condition that can cause permanent vision loss. The treatment strategy and visual outcome partly depend on the identification of the agents of pathogens. In this study, metagenomic sequencing was conducted to investigate the microbial and antibiotic resistance genes (ARGs) composition in the vitreous (intraocular body fluid) of an endophthalmitis patient, who progressed rapidly and accompanied by severe pain. Metagenomic sequencing data revealed that the vitreous sample was predominated by Streptococcus, with a low-diversity microbiome in the vitreous. This strain harbor's the ARGs mainly against beta-lactam, macrolide-lincosamide-streptogramin, and multidrug. Additionally, metagenome-assembled genome sequence of Streptococcus sp. v1. nov. was identified. The Tetra Correlation Search (TCS) analysis uncovered that the closest relative of the Streptococcus sp. v1. nov. was Streptococcus mitis SK321. Pan/core genome analysis for Streptococcus sp. v1. nov. and TCS top 25 hits strains revealed that most unique genes of Streptococcus sp. v1. nov. were linked to ATP-binding cassette transport system, which could indicate unique virulence and pathogenic potentials of Streptococcus sp. v1. nov. In addition, a total of 7 virulence factors were identified, and the overwhelming of them were classified into "offensive virulence factors". The high pathogenicity of Streptococcus sp. v1. nov. could be a reason for the patient's rapid disease progression. Our study was first isolated an ocular pathogen with highly virulent based on metagenomic sequencing and bioinformatics analysis, which has important reference value for revealing the composition and genome characteristics of pathogens in endophthalmitis patient in the future.

The optimized carbapenem inactivation method for objective and accurate detection of carbapenemase-producing Acinetobacter baumannii.

The modified carbapenem inactivation method (mCIM) recommended by the Clinical and Laboratory Standards Institute is not applicable for detecting carbapenemases in Acinetobacter baumannii. Four currently reported phenotypic detection methods, namely, the modified Hodge test, the mCIM, the adjusted mCIM, and the simplified carbapenem inactivation method (sCIM), did not perform well in our 90 clinical A. baumannii isolates. Thus, the minimal inhibitory concentrations (MICs) of carbapenems and the existence and expression of carbapenemase-encoding genes were detected to explain the results. According to the E-test, which was more accurate than the VITEK 2 system, 80.0 and 41.1% were resistant to imipenem (IPM) and meropenem (MEM), respectively, and 14.4 and 53.3% exhibited intermediate resistance, respectively. Five ß-lactamase genes were found, of which blaOXA-51-like, blaTEM, and blaOXA-23-like were detected more frequently in 85 non-susceptible strains. The expression of blaOXA-23-like was positively correlated with the MIC values of IPM and MEM. Therefore, an improved approach based on the mCIM, designated the optimized CIM (oCIM), was developed in this study to detect carbapenemases more accurately and reproducibly. The condition was improved by evaluating the factors of A. baumannii inoculum, incubation broth volume, and MEM disk incubation time. Obvious high sensitivity (92.94%) and specificity (100.00%) were obtained using the oCIM, which was cost-effective and reproducible in routine laboratory work.

Probiotic Lactobacillus Species and Their Biosurfactants Eliminate Acinetobacter baumannii Biofilm in Various Manners.

Acinetobacter baumannii is a critical biofilm-forming pathogen that has presented great challenges in the clinic due to multidrug resistance. Thus, new methods of intervention are needed to control biofilm-associated infections. In this study, among three tested Lactobacillus species, Lactobacillus rhamnosus showed significant antimaturation and antiadherence effects against A. baumannii biofilm. Lactic acid (LA) and acetic acid (AA) were the most effective antibiofilm biosurfactants (BSs) produced by L. rhamnosus. This antibiofilm phenomenon produced by LA and AA was due to the strong bactericidal effect, which worked from very early time points, as determined by colony enumeration and confocal laser scanning microscope. The cell destruction of A. baumannii appeared in both the cell envelope and cytoplasm. A discontinuous cell envelope, the leakage of cell contents, and the increased extracellular activity of ATPase demonstrated the disruption of the cell membrane by LA and AA. These effects also demonstrated the occurrence of protein lysis. In addition, bacterial DNA interacted with and was damaged by LA and AA, resulting in significantly reduced expression of biofilm and DNA repair genes. The results highlight the possibility and importance of using probiotics in clinical prevention. Probiotics can be utilized as novel biocides to block and decrease biofilm formation and microbial contamination in medical equipment and during the treatment of infections. IMPORTANCE A. baumannii biofilm is a significant virulence factor that causes the biofilm colonization of invasive illnesses. Rising bacterial resistance to synthetic antimicrobials has prompted researchers to look at natural alternatives, such as probiotics and their derivatives. In this study, L. rhamnosus and its BSs (LA and AA) demonstrated remarkable antibiofilm and antimicrobial characteristics, with a significant inhibitory effect on A. baumannii. These effects were achieved by several mechanisms, including the disruption of the cell envelope membrane, protein lysis, reduced expression of biofilm-related genes, and destruction of bacterial DNA. The results provide support for the possibility of using probiotics and their derivatives in the clinical prevention and therapy of A. baumannii infections.

Uncovering the Secretion Systems of Acinetobacter baumannii: Structures and Functions in Pathogenicity and Antibiotic Resistance.

Infections led by Acinetobacter baumannii strains are of great concern in healthcare environments due to the strong ability of the bacteria to spread through different apparatuses and develop drug resistance. Severe diseases can be caused by A. baumannii in critically ill patients, but its biological process and mechanism are not well understood. Secretion systems have recently been demonstrated to be involved in the pathogenic process, and five types of secretion systems out of the currently known six from Gram-negative bacteria have been found in A. baumannii. They can promote the fitness and pathogenesis of the bacteria by releasing a variety of effectors. Additionally, antibiotic resistance is found to be related to some types of secretion systems. In this review, we describe the genetic and structural compositions of the five secretion systems that exist in Acinetobacter. In addition, the function and molecular mechanism of each secretion system are summarized to explain how they enable these critical pathogens to overcome eukaryotic hosts and prokaryotic competitors to cause diseases.

Progranulin from different gliocytes in the nucleus accumbens exerts distinct roles in FTD- and neuroinflammation-induced depression-like behaviors.

BACKGROUND: Neuroinflammation in the nucleus accumbens (NAc) is well known to influence the progression of depression. However, the molecular mechanisms triggering NAc neuroinflammation in depression have not been fully elucidated. Progranulin (PGRN) is a multifunctional growth factor that is linked to the innate immune response and inflammation, and PGRN plays a key role in neurodegenerative diseases such as frontotemporal dementia (FTD). Here, the purpose of this study was to validate whether PGRN was involved in the NAc neuroinflammation-promoted depressive-like phenotype. METHODS: A NAc neuroinflammation-relevant depression-like model was established using wild-type (WT) and PGRN-knockout (KO) mice after NAc injection with lipopolysaccharide (LPS), and various behavioral tests related to cognition, social recognition, depression and anxiety were performed with WT and PGRNKO mice with or without NAc immune challenge. RT‒PCR, ELISA, western blotting and immunofluorescence staining were used to determine the expression and function of PGRN in the neuroinflammatory reaction in the NAc after LPS challenge. The morphology of neurons in the NAc from WT and PGRNKO mice under conditions of NAc neuroinflammation was analyzed using Golgi-Cox staining, followed by Sholl analyses. The potential signaling pathways involved in NAc neuroinflammation in PGRNKO mice were investigated by western blotting. RESULTS: Under normal conditions, PGRN deficiency induced FTD-like behaviors in mice and astrocyte activation in the NAc, promoted the release of the inflammatory cytokines interleukin (IL)-6 and IL-10 and increased dendritic complexity and synaptic protein BDNF levels in the NAc. However, NAc neuroinflammation enhanced PGRN expression, which was located in astrocytes and microglia within the NAc, and PGRN deficiency in mice alleviated NAc neuroinflammation-elicited depression-like behaviors, seemingly inhibiting astrocyte- and microglia-related inflammatory reactions and neuroplasticity complexity in the NAc via the p38 and nuclear factor of kappa (NF-κB) signaling pathways present in the NAc after neuroinflammation. CONCLUSIONS: Our results suggest that PGRN exerts distinct function on different behaviors, showing protective roles in the FTD-like behavior and detrimental effects on the neuroinflammation-related depression-like behavior, resulting from mediating astrocyte and microglial functions from the NAc in different status.

Maternal Methamphetamine Exposure Influences Behavioral Sensitization and Nucleus Accumbens DNA Methylation in Subsequent Generation.

The deleterious effects of methamphetamine (METH) exposure extend beyond abusers, and may potentially impact the vulnerability of their offspring in developing addictive behaviors. Epigenetic signatures have been implicated in addiction, yet the characteristics to identify prenatal METH abuse to offspring addiction risk remains elusive. Here, we used escalating doses of METH-exposed mouse model in F0 female mice before and during pregnancy to simulate the human pattern of drug abuse and generated METH-induced behavioral sensitization to investigate the addictive behavior in offspring mice. We then utilized whole genome-bisulfite sequencing (WGBS) to investigate the methylation signature of nucleus accumbens (NAc) in male METH-sensitized mice. Interestingly, male but not female offspring exhibited an enhanced response to METH-induced behavioral sensitization. Additionally, the METH-exposed group of male mice underwent a more comprehensive wave of epigenome remodeling over all genomic elements compared with unexposed groups due to drug exposure history. 104,219 DMCs (METH-SAL vs. SAL-SAL) induced by prenatal METH-exposure were positively correlated with that of postnatal METH-exposure (38,570, SAL-METH vs. SAL-SAL). Moreover, 4,983 DMCs induced by pre- and postnatal METH exposure (METH-METH vs. SAL-METH) were negatively correlated with that of postnatal METH exposure, and 371 commonly changed DMCs between the two comparison groups also showed a significantly negative correlation and 86 annotated genes functionally enriched in the pathways of neurodevelopment and addiction. Key annotated genes included Kirrel3, Lrpprc, and Peg3, implicated in neurodevelopmental processes, were down-regulated in METH-METH group mice compared with the SAL-METH group. Taken together, we render novel insights into the epigenetic correlation of drug exposure and provide evidence for epigenetic characteristics that link maternal METH exposure to the intensity of the same drug-induced behavioral sensitization in adult offspring.

Alterations in gut microbiota affect behavioral and inflammatory responses to methamphetamine in mice.

RATIONALE AND OBJECTIVES: Methamphetamine (METH) is a highly addictive and widely abused drug that causes severe neuroinflammation in the human brain. The gut microbiota has a tremendous impact on the core symptoms of neuropsychiatric disorders via the microbiota-gut-brain (MGB) axis. However, it is not clear whether alterations in the gut microbiota are involved in METH exposure. METHODS: We established a mouse model with chronic, escalating doses of METH exposure. Intervene in gut microbiota with antibiotics to observe the changes of locomotor activity caused by METH exposure in mice. qPCR and 16S rRNA gene sequencing were used to analyze the gut microbiota profiles. In addition, we tested the levels of inflammatory factors in the nucleus accumbens (NAc), prefrontal cortex (mPFC), hippocampus (HIp), and spleen. Finally, short-chain fatty acids (SCFAs) were supplemented to determine the interaction between behavior changes and the structure of gut microbiota. RESULTS: In this research, METH increased the locomotor activity of mice, while antibiotics changed the effect. Antibiotics enhanced the expression of pro-inflammatory cytokines in mPFC, HIp, and spleen of METH-exposed mice. METH altered the gut microbiota of mice after antibiotic treatment, such as Butyricicoccus and Roseburia, which are related to butyrate metabolism. Supplementation with SCFAs changed the behavior of METH-exposed mice and decreased Parabacteroides and increased Lactobacillus in METH-exposed mice gut. CONCLUSIONS: This research showed that antibiotics affected the behavior of METH-exposed mice and promoted inflammation. Our findings suggest that SCFAs might regulate METH-induced gut microbiota changes and behavior.

cGAS modulates cytokine secretion and bacterial burdens by altering the release of mitochondrial DNA in pseudomonas pulmonary infection.

Cyclic GMP-AMP synthase (cGAS) is essential for fighting against viruses and bacteria, but how cGAS is involved in host immune response remains largely elusive. Here, we uncover the crucial role of cGAS in host immunity based on a Pseudomonas aeruginosa pulmonary infection model. cGAS-/- mice showed more heavy bacterial burdens and serious lung injury accompanied with exorbitant proinflammatory cytokines than wild-type mice. cGAS deficiency caused an accumulation of mitochondrial DNA in the cytoplasm, which, in turn, induced excessive secretion of proinflammatory factors by activating inflammasome and TLR9 signalling. Mechanistically, cGAS deficiency inhibited the recruitment of LC3 by reducing the binding capacity of TBK-1 to p62, leading to impaired mitophagy and augmented release of mitochondrial DNA. Importantly, cytoplasmic mitochondrial DNA also acted as a feedback signal that induced the activation of cGAS. Altogether, these findings identify protective and homeostasis functions of cGAS against Pseudomonas aeruginosa infection, adding significant insight into the pathogenesis of bacterial infectious diseases.

Dopamine D3 receptor signaling alleviates mouse rheumatoid arthritis by promoting Toll-like receptor 4 degradation in mast cells.

Dopamine receptors are involved in several immunological diseases. We previously found that dopamine D3 receptor (D3R) on mast cells showed a high correlation with disease activity in patients with rheumatoid arthritis, but the mechanism remains largely elusive. In this study, a murine collagen-induced arthritis (CIA) model was employed in both DBA/1 mice and D3R knockout mice. Here, we revealed that D3R-deficient mice developed more severe arthritis than wild-type mice. D3R suppressed mast cell activation in vivo and in vitro via a Toll-like receptor 4 (TLR4)-dependent pathway. Importantly, D3R promoted LC3 conversion to accelerate ubiquitin-labeled TLR4 degradation. Mechanistically, D3R inhibited mTOR and AKT phosphorylation while enhancing AMPK phosphorylation in activated mast cells, which was followed by autophagy-dependent protein degradation of TLR4. In total, we found that D3R on mast cells alleviated inflammation in mouse rheumatoid arthritis through the mTOR/AKT/AMPK-LC3-ubiquitin-TLR4 signaling axis. These findings identify a protective function of D3R against excessive inflammation in mast cells, expanding significant insight into the pathogenesis of rheumatoid arthritis and providing a possible target for future treatment.

Dopamine D3 receptor in the nucleus accumbens alleviates neuroinflammation in a mouse model of depressive-like behavior.

We recently reported that dopamine D3 receptor (D3R) was involved in inflammation-related depression. Nucleus accumbens (NAc) inflammation is implicated in the development and progression of depression, but its regulatory mechanism remains largely unknown. In a mouse model of NAc neuroinflammation induced by bilateral NAc injection of lipopolysaccharide (LPS), we observed that NAc neuroinflammation triggered depressive-like behaviors, and D3R expression decline and microglial activation in the NAc. A selective knockdown of D3R in the NAc elicited depressive-like behaviors, while re-expression of D3R in the NAc of global D3RKO mice alleviated depressive-like behaviors induced by D3R deficiency. D3R downregulation in the NAc shifted microglia toward a proinflammatory state, which was validated with cultured mouse microglial cultures. Further in vitro results demonstrated that D3R inhibition induced microglia to enter a proinflammatory state primarily through the Akt signaling pathway. In conclusion, our results suggest that D3R expression in the NAc may inhibit microglial proinflammatory responses in the NAc, thus alleviating NAc neuroinflammation and subsequent depressive-like behaviors through the Akt signaling pathway.

Curcumin alleviates imiquimod-induced psoriasis in progranulin-knockout mice.

Recent advances have revealed that progranulin (PGRN) is related to the aetiology of psoriasis. Moreover, curcumin, a compound derived from turmeric, has been proposed as a potential therapeutic approach in psoriasis-like dermatitis, but it is still unclear whether curcumin affects the development of psoriasis-like skin lesions under PGRN-deficient conditions. Therefore, in this study, we developed a mouse model of psoriatic skin lesions using topical application of imiquimod (IMQ) in both wild type and PGRN-knockout mice to test this possibility. We observed that PGRN deficiency not only increased proinflammatory cytokine IL-17A levels and aggravated psoriasis-like damaged appearance and epidermal thickening but also directly mediated changes in keratinocyte proliferation (Krt 14, cyclinD1 and c-Myc) and differentiation (Krt 10 and Filaggrin) associated gene expression following IMQ challenge, compared to those in the control group. Furthermore, curcumin treatment (50 mg/kg and 200 mg/kg, intragastrically) for 21 consecutive days suppressed the IMQ exposure-induced increase in PGRN expression. Importantly, curcumin treatment significantly alleviated the PGRN deficiency-induced exacerbation of psoriatic appearance, histological features and keratinocyte proliferation after IMQ exposure. In summary, these results demonstrate the direct regulation of PGRN in keratinocyte proliferation and differentiation in psoriatic lesions and demonstrate the protective effect of curcumin on PGRN deficiency-induced psoriatic skin lesion exacerbation.

Phenotypic and genotypic characteristics of Acinetobacter baumannii enrolled in the relationship among antibiotic resistance, biofilm formation and motility.

Acinetobacter baumannii is an important pathogen in clinical. The factors of biofilm formation, antibiotic resistance and motility contribute great to A. baumannii in persisting in stressed environment, and further leads to nosocomial infections. 70 A. baumannii clinical isolates were investigated for their clinical characteristics of infection. Among the tested strains, 54 (77.1%) isolates were obtained from ICUs, with the frequency of multidrug-resistance (MDR) at 55.7%, and that of extensively drug-resistance (XDR) at 31.4%. 97.1% of the clinical isolates could form biofilms, in which 4.3% possessed weak biofilm formation ability, while 41.4% and 51.4% were moderate and strong biofilm producers, respectively. A strong correlation between antibiotic resistance and biofilm formation ability was found that all the resistant strains could form biofilms, with the majority in moderate and strong levels, but 2.9% sensitive isolates had no such ability. However, the sensitive strains that could produce biofilms showed stronger biofilm formation capacity in the early stage before 24 h compared to the resistant isolates, though they became weaker afterwards. 24 biofilm-related genes and two blaOXA genes were found in both biofilm-forming and non-biofilm-forming strains, but with higher prevalence in the strains that could produce biofilms. No correlation was detected between twitching motility with antibiotic susceptibility or biofilm formation. These results raised a viewpoint that examining timepoint is a key factor for determining the biofilm formation ability, and further highlighted the importance of the appropriate surveillance and control measures in preventing the emergence and transmission of MDR and XDR A. baumannii.

Serum Progranulin As a Risk Predictor in Patients with Acute Myocardial Infarction.

BACKGROUND Although progranulin was recently proposed as an adipokine that may be involved in glucose metabolic and inflammatory diseases, the role of serum progranulin in cardiovascular disease is elusive and remains disputed. The aim of our research was to determine the concentration of serum progranulin in Chinese patients with cardiovascular disease, notably in acute myocardial infarction (AMI), and its relationship to other cardiometabolic risk factors. MATERIAL AND METHODS This prospective observational study included 342 Chinese AMI patients and 255 healthy control subjects. Serum progranulin concentrations and various cardiometabolic risk factor levels were investigated. We assessed the relationship between progranulin and other cardiometabolic risk factors. Logistic regression analysis was applied to evaluate risk factors in patients with AMI. RESULTS Progranulin levels were obviously elevated in AMI patients compared to control subjects (P=0.0001). Correlation analysis showed that progranulin levels were positively associated with coronary artery disease severity (r=0.380, P=0.0001), glucose (r=0.195, P=0.015), and myeloperoxidase (r=0.198, P=0.014). In logistic regression analysis, serum progranulin (Exp(B)=1.104, 95% CI=1.043-1.168, P=0.001), myeloperoxidase (Exp(B)=1.006, 95% CI=1.003-1.008, P=0.0001), and uric acid (Exp(B)=1.020, 95% CI=1.009-1.032, P=0.0001) were independent risk factors in AMI patients. CONCLUSIONS Patients with AMI had significantly higher serum progranulin concentrations than control subjects. This study suggests that serum progranulin is an independent risk predictor in Chinese patients with AMI.

Microglial activation contributes to depressive-like behavior in dopamine D3 receptor knockout mice.

We previously demonstrated that the dopamine D3 receptor (D3R) inhibitor, NGB2904, increases susceptibility to depressive-like symptoms, elevates pro-inflammatory cytokine expression, and alters brain-derived neurotrophic factor (BDNF) levels in mesolimbic dopaminergic regions, including the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), and ventral tegmental area (VTA) in mice. The mechanisms by which D3R inhibition affects neuroinflammation and onset of depression remain unclear. Here, using D3R-knockout (D3RKO) and congenic wild-type C56BL/6 (WT) mice, we demonstrated that D3RKO mice displayed depressive-like behaviors, increased tumornecrosisfactor-α (TNF-α), interleukin-1ß (IL-1ß), and IL-6 levels, and altered BDNF expression in selected mesolimbic dopaminergic regions. D3R expression was localized to astrocytes or microglia in the mPFC, NAc, and VTA in WT mice. D3RKO mice exhibited a large number of Iba1-labelled microglia in the absence of glial fibrillary acidic protein (GFAP)-labelled astrocytes in mesolimbic dopaminergic brain areas. Inhibition or ablation of microglia by minocycline (25 mg/kg and 50 mg/kg) or PLX3397 (40 mg/kg) treatment ameliorated depressive-like symptoms, alterations in pro-inflammatory cytokine levels, and BDNF expression in the indicated brain regions in D3RKO mice. Minocycline therapy alleviated the increase in synaptic density in the NAc in D3RKO mice. These findings suggest that microglial activation in selected mesolimbic reward regions affects depressive-like behaviors induced by D3R deficiency.

Methamphetamine exacerbates neuroinflammatory response to lipopolysaccharide by activating dopamine D1-like receptors.

Methamphetamine (METH) is a highly addictive and widely abused drug worldwide. Although much research is on the drug's direct effects, METH may also alter host immunity. The mechanism by which METH influences immunity remains elusive. Here, C57BL6/J mice were intraperitoneally injected with 5 mg/kg METH four times at two-hour intervals. The microglial inhibitor minocycline or dopamine D1-like receptor antagonist SCH-23390 was also applied prior to METH injection. Twenty-four hours following the first METH injection, mice were challenged by lipopolysaccharide (LPS) at a dose of 330 µg/kg, and the hippocampus (Hip), caudate putamen (CPU), nucleus accumbens (NAc) and prefrontal cortex (PFC) were collected 4 h after LPS administration. IL-6 and TNF-α levels were detected by ELISA. The activation of D1-like receptors and microglial marker Iba1 were examined by immunohistochemical staining and Western blot. Finally, we examined the phosphorylation of ERK1/2 and CREB. We found that METH exposure increased LPS-induced IL-6 and TNF-α production in the Hip, CPU and NAc regions. METH also augmented microglia activation and D1/5DR expression in response to LPS. Moreover, administering SCH-23390 significantly reduced IL-6 and TNF-α production and Iba1 expression following LPS challenge. Similar inhibitory effects were also observed by minocycline administration. Moreover, phosphorylation of ERK1/2 and CREB was increased after METH and LPS exposure but decreased by SCH-23390. These data illustrate that METH exacerbates neuroinflammation response in LPS-stimulated mouse brains through dopamine D1-like receptors, microglia, and relevant signaling proteins, which may have therapeutic implications.

Dopamine Alters Lipopolysaccharide-Induced Nitric Oxide Production in Microglial Cells via Activation of D1-Like Receptors.

Dopamine (DA) is important in the maintenance of normal nervous system function. DA is the target of multiple drugs, and it induces critical alterations in immune cells. However, these impacts are controversial, and the mechanism remains unclear. In the present study, we treated BV-2 microglial cells and primary microglia with DA and measured the changes in cytokines. We also identified the expression of DA receptors (DRs) using confocal and immunofluorescent microscopy. Specific agonists and antagonists of D1-like DRs (D1DR and D5DR) were used to observe alterations in cytokines. Western blot and siRNA interference were performed to investigate the involvement of the downstream signaling molecules of DRs. We also measured changes in mitogen-activated protein kinases (MAPKs) and the nuclear factor-kappa B (NF-κB) signaling pathway and assessed their involvement using inhibitors. We found that DA alone produced no effects on IL-6, TNF-α or nitric oxide (NO) production, and it inhibited lipopolysaccharide (LPS)-induced NO in microglial cells. Microglia expressed a high abundance of D1-like DRs (D1DR and D5DR). The agonists inhibited NO production, and antagonists reversed the DA-induced suppression of NO. Adenylatec cyclase (AC), cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) mediated DA function, and cAMP-response element binding protein (CREB) was not involved. ERK1/2 and NF-κB, but not p-38 or JNK, played roles in DA-suppressed NO generation via altering inducible nitric oxide synthase (iNOS) transcription. These data illustrate that DA modulates LPS-induced NO production via the AC/cAMP-PKA-ERK1/2-NF-κB-iNOS axis in mouse microglia, and D1-like DRs are involved. The present study provides functional evidence for an essential role of DA in immunoregulation.

Ago2 and Dicer1 are involved in METH-induced locomotor sensitization in mice via biogenesis of miRNA.

microRNA (miRNA) play important roles in drug addiction and act as a post-transcriptional regulator of gene expression. We previously reported extensive downregulation of miRNAs in the nucleus accumbens (NAc) of methamphetamine (METH)-sensitized mice. However, the regulatory mechanism of this METH-induced downregulation of miRNAs has yet to be elucidated. Thus, we examined METH-induced changes in the expression of miRNAs and their precursors, as well as the expression levels of mRNA and the proteins involved in miRNA biogenesis such as Dicer1 and Ago2, in the nucleus accumbens of METH-induced locomotor sensitized mice. miRNAs and Ago2 were significantly downregulated, while the expression of miRNA precursors remained unchanged or upregulated, which suggests that the downregulation of miRNAs was likely due to a reduction in Ago2-mediated splicing but unlikely to be regulated at the transcription level. Interestingly, the expression level of Dicer1, which is a potential target of METH-induced decreased miRNAs, such as miR-124, miR-212 and miR-29b, was significantly increased. In conclusion, this study indicates that miRNA biogenesis (such as Ago2 and Dicer1) and their miRNA products may have a role in the development of METH addiction.

Inhibitory effects of methamphetamine on mast cell activation and cytokine/chemokine production stimulated by lipopolysaccharide in C57BL/6J mice.

Previous studies have demonstrated that methamphetamine (MA) influences host immunity; however, the effect of MA on lipopolysaccharide (LPS)-induced immune responses remains unknown. Mast cells (MCs) are considered to serve an important role in the innate and acquired immune response, but it remains unknown whether MA modulates MC activation and LPS-stimulated cytokine production. The present study aimed to investigate the effect of MA on LPS-induced MC activation and the production of MC-derived cytokines in mice. Markers for MC activation, including cluster of differentiation 117 and the type I high affinity immunoglobulin E receptor, were assessed in mouse intestines. Levels of MC-derived cytokines in the lungs and thymus were also examined. The results demonstrated that cytokines were produced in the bone marrow-derived mast cells (BMMCs) of mice. The present study demonstrated that MA suppressed the LPS-mediated MC activation in mouse intestines. MA also altered the release of MC cytokines in the lung and thymus following LPS stimulation. In addition, LPS-stimulated cytokines were decreased in the BMMCs of mice following treatment with MA. The present study demonstrated that MA may regulate LPS-stimulated MC activation and cytokine production.

The inhibitory effect of levo-tetrahydropalmatine on the methamphetamine-induced spatial memory impairment in mice.

Methamphetamine (METH) administration results in addiction and memory impairment. Previous studies have suggested that levo-tetrahydropalmatine (l-THP), an alkaloid purified from the Chinese herb Corydalis, attenuates the behavioral changes induced by METH. Therefore, in this study, we explored whether l-THP could also protect against the METH-induced memory impairment examined using the Morris water maze (MWM). We found that low dose of METH (1.0 mg/kg) treated for 20 consecutive days prior to the MWM experiment impaired spatial memory retention but not acquisition in mice. In addition, high dose of METH (10.0 mg/kg) treated during the spatial learning phase for five consecutive days impaired both the acquisition and retention of spatial memory. Moreover, both of these impairments induced by METH were reversed by l-THP treatment, indicating a potential protective role of l-THP in METH use.