The Role of Medial Habenula-Interpeduncular Nucleus Pathway in Anxiety: A Dissertation

Recently, the medial habenula-interpeduncular (MHb-IPN) axis has been hypothesized to modulate anxiety although neuronal populations and molecular mechanisms regulating affective behaviors in this circuit are unknown. Here we show that MHb cholinergic neuron activity directly regulates anxiety-like behavior. Optogenetic silencing of MHb cholinergic IPN inputs reduced anxiety-like behavior in mice. MHb cholinergic neurons are unique in that they robustly express neuronal nicotinic acetylcholine receptors (nAChRs), although their role as autoreceptors in these neurons has not been described. nAChRs are ligand-gated cation channels that are activated by the excitatory neurotransmitter, acetylcholine (ACh), as well as nicotine, the addictive component of tobacco smoke. We expressed novel nAChR subunits that render nAChRs hypersensitive to ACh, ACh detectors, selectively in MHb cholinergic neurons of adult mice. Mice expressing these ACh detectors exhibited increased baseline anxiety-like behavior that was alleviated by blocking the mutant receptors. Under stressful conditions, such as during nicotine withdrawal, nAChRs were functionally upregulated in MHb cholinergic neurons mediating an increase in anxiety-like behavior. Together, these data indicate that MHb cholinergic neurons regulate anxiety via signaling through nicotinic autoreceptors and point toward nAChRs in MHb as molecular targets for novel anxiolytic therapeutics

Activation of alpha4* nAChRs is necessary and sufficient for varenicline-induced reduction of alcohol consumption

Recently, the smoking cessation therapeutic varenicline, a nicotinic acetylcholine receptor (nAChR) partial agonist, has been shown to reduce alcohol consumption. However, the mechanism and nAChR subtype(s) involved are unknown. Here we demonstrate that varenicline and alcohol exposure, either alone or in combination, selectively activates dopaminergic (DAergic) neurons within the posterior, but not the anterior, ventral tegmental area (VTA). To gain insight into which nAChR subtypes may be involved in the response to alcohol, we analyzed nAChR subunit gene expression in posterior VTA DAergic neurons. Ethanol-activated DAergic neurons expressed higher levels of alpha4, alpha6, and beta3 subunit genes compared with nonactivated neurons. To examine the role of nicotinic receptors containing the alpha4 subunit (alpha4* nAChRs) in varenicline-induced reduction of alcohol consumption, we examined the effect of the drug in two complementary mouse models, a knock-out line that does not express the alpha4 subunit (alpha4 KO) and another line that expresses alpha4* nAChRs hypersensitive to agonist (Leu9\u27Ala). While varenicline (0.1-0.3 mg/kg, i.p.) reduced 2% and 20% alcohol consumption in wild-type (WT) mice, the drug did not significantly reduce consumption in alpha4 KO animals. Conversely, low doses of varenicline (0.0125-0.05 mg/kg, i.p.) that had little effect in WT mice dramatically reduced ethanol intake in Leu9\u27Ala mice. Infusion of varenicline into the posterior, but not the anterior VTA was sufficient to reduce alcohol consumption. Together, our data indicate that activation of alpha4* nAChRs is necessary and sufficient for varenicline reduction of alcohol consumption

Quorum Sensing of Acidophiles: A Communication System in Microorganisms

Communication is important for organisms living in nature. Quorum sensing system (QS) are intercellular communication systems that promote the sociality of microbes. Microorganisms could promote cell-to-cell cooperation and population density to adapt to the changing environment through QS-mediated regulation that is dependent on the secretion and the detection of signal molecules (or called autoinducers). QS system is also discovered in acidophiles, a microorganism that is widely used in the bioleaching industry and can live in an acidic environment. An example is the LuxI/R-like QS system (AfeI/R) that has been reported in the chemoautotrophic species of the genus Acidithiobacillus. In this chapter, we will introduce the types and distribution of the QS system, and the biological function and regulatory mechanism of QS in acidophiles. We will also discuss the potential ecological function of QS system and the application value of the QS system in the control and regulation of the bioleaching process in the related industries and acid mine damage

A multimodal cell census and atlas of the mammalian primary motor cortex

ABSTRACT We report the generation of a multimodal cell census and atlas of the mammalian primary motor cortex (MOp or M1) as the initial product of the BRAIN Initiative Cell Census Network (BICCN). This was achieved by coordinated large-scale analyses of single-cell transcriptomes, chromatin accessibility, DNA methylomes, spatially resolved single-cell transcriptomes, morphological and electrophysiological properties, and cellular resolution input-output mapping, integrated through cross-modal computational analysis. Together, our results advance the collective knowledge and understanding of brain cell type organization: First, our study reveals a unified molecular genetic landscape of cortical cell types that congruently integrates their transcriptome, open chromatin and DNA methylation maps. Second, cross-species analysis achieves a unified taxonomy of transcriptomic types and their hierarchical organization that are conserved from mouse to marmoset and human. Third, cross-modal analysis provides compelling evidence for the epigenomic, transcriptomic, and gene regulatory basis of neuronal phenotypes such as their physiological and anatomical properties, demonstrating the biological validity and genomic underpinning of neuron types and subtypes. Fourth, in situ single-cell transcriptomics provides a spatially-resolved cell type atlas of the motor cortex. Fifth, integrated transcriptomic, epigenomic and anatomical analyses reveal the correspondence between neural circuits and transcriptomic cell types. We further present an extensive genetic toolset for targeting and fate mapping glutamatergic projection neuron types toward linking their developmental trajectory to their circuit function. Together, our results establish a unified and mechanistic framework of neuronal cell type organization that integrates multi-layered molecular genetic and spatial information with multi-faceted phenotypic properties

Analyses of Transcriptomics upon IL-1β-Stimulated Mouse Chondrocytes and the Protective Effect of Catalpol through the NOD2/NF-κB/MAPK Signaling Pathway

The overall objective of this study was to investigate the mechanism of inflammation on chondrocyte injury and the protective effect of catalpol on chondrocytes in an inflammatory environment. Chondrocytes were isolated and cultured from the knee joints of three-day-old newborn mice. Alcian Blue staining and the immunocytochemistry staining of type II collagen were used to identify the purity of chondrocytes. Primary chondrocytes were stimulated by IL-1β (10 ng/mL) and subjected to transcriptome analysis. Differentially expressed genes (DEGs) were further analyzed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. In this experimental study, we performed the viability assay to determine the effects of different concentrations of catalpol on the cell viability of chondrocytes. Chondrocytes were seeded in six-well plates and exposed to 10 μM catalpol 2 h prior to treatment with IL-1β (10 ng/mL). Quantitative real-time (qPCR) and Western blotting were performed to evaluate the RNA and protein expression, respectively. Based on the results of transcriptomics analysis, we found the NOD2 signaling pathway, the NF-kappa B signaling pathway, and the MAPK signaling pathway showed significant changes in chondrocyte damage caused by inflammation. Catalpol (10 μM and 100 μM) could significantly reduce NO, IL-6, IL-1β, and TNF-α in supernatant of chondrocytes. Catalpol significantly inhibited the mRNA expression of IL-1, IL-6, and IL-12 in chondrocytes induced by IL-1β. Catalpol markedly inhibited MMP3, MMP13 mRNA, and protein levels. Catalpol could significantly reduce TNF-α mRNA levels in inflammatory chondrocytes. Inflammation causes significant increases in mRNA levels and protein levels of NOD2, mRNA levels, and protein levels were markedly suppressed by catalpol. In addition, catalpol could significantly increase IKBα protein levels and significantly lower intranuclear P65 levels. Catalpol significantly lowered the phosphorylation protein levels of ERK, p38, and JNK. Our transcriptomic analysis demonstrated that the activation of NOD2 and its downstream pathways, NF-κB and MAPK, is an important cause of the inflammatory injury to chondrocytes induced by IL-1β. Catalpol inhibited the activation of the NOD2 signaling pathway, which reduced the phosphorylation of ERK, p38, and JNK, inhibited the degradation of IκBα, inhibited p65 translocation into the nucleus, reduced the release of inflammatory cytokines, and attenuated the inflammatory damage to chondrocytes

Study on the Construction of a Health Lifestyle for Older People in the Longevous Area in China

During the past 40 years of reform and opening-up, China has witnessed great progress in people’s health status. Both the occurrence of diseases and people’s understanding of health have undergone profound changes. Scholars are focusing on changing socioeconomic factors to maintain health lifestyles, and creating healthy “human–land” relations to prevent diseases. From the perspective of health geography, this research conducted field work in Bama, a longevous area in the Guangxi province in China, and applied the theoretical framework of health lifestyles theory to clarify the construction process of health lifestyles for older people in Bama. The roles and characteristics of different social relations in creating health lifestyles are revealed. The findings of this research can provide a new paradigm for China’s health practice research from two aspects: (1) the production of health lifestyles is a knowledge construction process, taking into account the influence of social circumstances, politics, economy, culture, policy, and values; and (2) social attributes affect health lifestyles by reconstructing and improving social relations

Activation of GABAergic Neurons in the Interpeduncular Nucleus Triggers Physical Nicotine Withdrawal Symptoms

BACKGROUND: Chronic exposure to nicotine elicits physical dependence in smokers, yet the mechanism and neuroanatomical bases for withdrawal symptoms are unclear. As in humans, rodents undergo physical withdrawal symptoms after cessation from chronic nicotine characterized by increased scratching, head nods, and body shakes. RESULTS: Here we show that induction of physical nicotine withdrawal symptoms activates GABAergic neurons within the interpeduncular nucleus (IPN). Optical activation of IPN GABAergic neurons via light stimulation of channelrhodopsin elicited physical withdrawal symptoms in both nicotine-naive and chronic-nicotine-exposed mice. Dampening excitability of GABAergic neurons during nicotine withdrawal through IPN-selective infusion of an NMDA receptor antagonist or through blockade of IPN neurotransmission from the medial habenula reduced IPN neuronal activation and alleviated withdrawal symptoms. During chronic nicotine exposure, nicotinic acetylcholine receptors containing the β4 subunit were upregulated in somatostatin interneurons clustered in the dorsal region of the IPN. Blockade of these receptors induced withdrawal signs more dramatically in nicotine-dependent compared to nicotine-naive mice and activated nonsomatostatin neurons in the IPN. CONCLUSIONS: Together, our data indicate that therapeutic strategies to reduce IPN GABAergic neuron excitability during nicotine withdrawal, for example, by activating nicotinic receptors on somatostatin interneurons, may be beneficial for alleviating withdrawal symptoms and facilitating smoking cessation

Dicer expression is essential for adult midbrain dopaminergic neuron maintenance and survival

The type III RNAse, Dicer, is responsible for the processing of microRNA (miRNA) precursors into functional miRNA molecules, non-coding RNAs that bind to and target messenger RNAs for repression. Dicer expression is essential for mouse midbrain development and dopaminergic (DAergic) neuron maintenance and survival during the early post-natal period. However, the role of Dicer in adult mouse DAergic neuron maintenance and survival is unknown. To bridge this gap in knowledge, we selectively knocked-down Dicer expression in individual DAergic midbrain areas, including the ventral tegmental area (VTA) and substantia nigra pars compacta (SNpc) via viral-mediated expression of Cre in adult floxed Dicer knock-in mice (Dicer(flox/flox)). Bilateral Dicer loss in the VTA resulted in progressive hyperactivity that was significantly reduced by the dopamine agonist, amphetamine. In contrast, decreased Dicer expression in the SNpc did not affect locomotor activity but did induce motor-learning impairment on an accelerating rotarod. Knock-down of Dicer in both midbrain regions of adult Dicer(flox/flox) mice resulted in preferential, progressive loss of DAergic neurons likely explaining motor behavior phenotypes. In addition, knock-down of Dicer in midbrain areas triggered neuronal death via apoptosis. Together, these data indicate that Dicer expression and, as a consequence, miRNA function, are essential for DAergic neuronal maintenance and survival in adult midbrain DAergic neuron brain areas

Habenula cholinergic neurons regulate anxiety during nicotine withdrawal via nicotinic acetylcholine receptors

Cholinergic neurons in the medial habenula (MHb) modulate anxiety during nicotine withdrawal although the molecular neuroadaptation(s) within the MHb that induce affective behaviors during nicotine cessation is largely unknown. MHb cholinergic neurons are unique in that they robustly express neuronal nicotinic acetylcholine receptors (nAChRs), although their behavioral role as autoreceptors in these neurons has not been described. To test the hypothesis that nAChR signaling in MHb cholinergic neurons could modulate anxiety, we expressed novel gain of function nAChR subunits selectively in MHb cholinergic neurons of adult mice. Mice expressing these mutant nAChRs exhibited increased anxiety-like behavior that was alleviated by blockade with a nAChR antagonist. To test the hypothesis that anxiety induced by nicotine withdrawal may be mediated by increased MHb nicotinic receptor signaling, we infused nAChR subtype selective antagonists into the MHb of nicotine naive and withdrawn mice. While antagonists had little effect on nicotine naive mice, blocking alpha4beta2 or alpha6beta2, but not alpha3beta4 nAChRs in the MHb alleviated anxiety in mice undergoing nicotine withdrawal. Consistent with behavioral results, there was increased functional expression of nAChRs containing the alpha6 subunit in MHb neurons that also expressed the alpha4 subunit. Together, these data indicate that MHb cholinergic neurons regulate nicotine withdrawal-induced anxiety via increased signaling through nicotinic receptors containing the alpha6 subunit and point toward nAChRs in MHb cholinergic neurons as molecular targets for smoking cessation therapeutics