The influence of adolescent nicotine exposure on ethanol intake and brain gene expression

PLoS One . 2018 Jun 18;13(6):e0198935. doi: 10.1371/journal.pone.0198935. eCollection 2018.

Constanza P Silva ¹, William J Horton ², Michael J Caruso ¹, Aswathy Sebastian ³, Laura C Klein ¹, Istvan Albert ³, Helen M Kamens ¹

• PMID: 29912970
• PMCID: PMC6005571
• DOI: 10.1371/journal.pone.0198935

Abstract

Nicotine and alcohol are often co-abused. Adolescence is a vulnerable period for the initiation of both nicotine and alcohol use, which can lead to subsequent neurodevelopmental and behavioral alterations. It is possible that during this vulnerable period, use of one drug leads to neurobiological alterations that affect subsequent consumption of the other drug. The aim of the present study was to determine the effect of nicotine exposure during adolescence on ethanol intake, and the effect of these substances on brain gene expression. Forty-three adolescent female C57BL/6J mice were assigned to four groups. In the first phase of the experiment, adolescent mice (PND 36-41 days) were exposed to three bottles filled with water or nicotine (200 μg/ml) for 22 h a day and a single bottle of water 2 h a day for six days. In the second phase (PND 42-45 days), the 4-day Drinking-in-the-Dark paradigm consisting of access to 20% v/v ethanol or water for 2h or 4h (the last day) was overlaid during the time when the mice did not have nicotine available. Ethanol consumption (g/kg) and blood ethanol concentrations (BEC, mg %) were measured on the final day and whole brains including the cerebellum, were dissected for RNA sequencing. Differentially expressed genes (DEG) were detected with CuffDiff and gene networks were built using WGCNA. Prior nicotine exposure increased ethanol consumption and resulting BEC. Significant DEG and biological pathways found in the group exposed to both nicotine and ethanol included genes important in stress-related neuropeptide signaling, hypothalamic-pituitary-adrenal (HPA) axis activity, glutamate release, GABA signaling, and dopamine release. These results replicate our earlier findings that nicotine exposure during adolescence increases ethanol consumption and extends this work by examining gene expression differences which could mediate these behavioral effects.

Transient receptor potential ankyrin 1 (TRPA1) positively regulates imiquimod‐induced, psoriasiform dermal inflammation in mice

YanZhou1,2 | DanHan1,2 BoWang4 | ZhenruiShi2 Samuel T. Hwang2 TaylorFollansbee3 | XuesongWu2 | SebastianYu2 | | DanT.Domocos3 | MirelaCarstens3 | EarlCarstens3 |

1Department of Dermatology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China

2Department of Dermatology, University of California, Davis, California

3Department of Neurobiology, Physiology and Behavior, University of California, Davis, California

4Center for Translational Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China

Abstract

Transient receptor potential ankyrin 1 (TRPA1), a membrane protein ion channel, is known to mediate itch and pain in skin. The function of TRPA1, however, in psori‐ asiform dermatitis (PsD) is uncertain. Herein, we found that expression of TRPA1 is highly up‐regulated in human psoriatic lesional skin. To study the role of TRPA1 in PsD, we assessed Psoriasis Severity Index (PSI) scores, transepidermal water loss (TEWL), skin thickness and pathology, and examined dermal inflammatory infiltrates, Th17‐related genes and itch‐related genes in c57BL/6 as wild‐type (WT) and TRPA1 gene knockout (KO) mice following daily application of topical IMQ cream for 5 days. Compared with WT mice, clinical scores, skin thickness change and TEWL scores were similar on day 3, but were significantly decreased on day 5 in IMQ‐treated TRPA1 KO mice (vs WT mice), suggesting reduced inflammation and skin barrier de‐ fects. Additionally, the relative area of epidermal Munro’s microabscesses and mRNA levels of neutrophil inducible chemokines (S100A8, S100A9 and CXCL1) were de‐ creased in the treated skin of TRPA1 KO mice, suggesting that neutrophil recruitment was impaired in the KO mice. Furthermore, mast cells, CD31+ blood vascular cells, CD45+ leukocytes and CD3+ T cells were all reduced in the treated skin of TRPA1 KO mice. Lastly, mRNA expression levels of IL‐1β, IL‐6, IL‐23, IL‐17A, IL‐17F and IL‐22 were decreased in TRPA1 KO mice. In summary, these results suggest a key role for TRPA1 in psoriasiform inflammation and raising its potential as a target for therapeu‐ tic intervention.

KEYWORDS

imiquimod, inflammation, itch, mice, psoriasis, TRPA1

Spinal Inhibitory Ptf1a-Derived Neurons Prevent Self-Generated Itch

Augusto Escalante , Rüdiger Klein

Abstract

Chronic itch represents an incapacitating burden on patients suffering from a spectrum of diseases. Despite recent advances in our understanding of the cells and circuits implicated in the processing of itch information, chronic itch often presents itself without an apparent cause. Here, we identify a spinal subpopulation of inhibitory neurons defined by the expression of Ptf1a, involved in gating mechanosensory information self-generated during movement. These neurons receive tactile and motor input and establish presynaptic inhibitory contacts on mechanosensory afferents. Loss of Ptf1a neurons leads to increased hairy skin sensitivity and chronic itch, partially mediated by the classic itch pathway involving gastrin-releasing peptide receptor (GRPR) spinal neurons. Conversely, chemogenetic activation of GRPR neurons elicits itch, which is suppressed by concomitant activation of Ptf1a neurons. These findings shed light on the circuit mechanisms implicated in chronic itch and open novel targets for therapy developments.

Keywords: DREADD receptors; GRPR; Ptf1a; dorsal horn interneurons; intersectional genetics; itch; spinal cord.

A Group of Cationic Amphiphilic Drugs Activates MRGPRX2 and Induces Scratching Behavior in Mice

Katharina Wolf, PhD#*a , Helen Kühn, PhD#a , Felicitas Boehm, MSca , Lisa Gebhardt, MSca , Markus Glaudo, MSc , Konstantin Agelopoulos, PhDb , Sonja Ständer, MDb , Philipp Ectors, PhDc , Dirk Zahn, PhDc , Yvonne K. Riedel, MScd , Dominik Thimm, PhDd , Christa E. Müller, PhDd , Sascha Kretschmann, PhDe , Anita N. Kremer, MD, PhDe , Daphne Chienf, BSc, Nathachit Limjunyawongf , PhD, Qi Pengf , Xinzhong Dong, PhDf , Pavel Kolkhir, MDg,h , Jörg Scheffel, PhDh , Mia Lykke Søgaard, MSca , Benno Weigmann, PhDa , Markus F. Neurath, MDa,i, Tomasz Hawro, MD, PhDh , Martin Metz, MDh , Michael J.M. Fischer, MDj , Andreas E. Kremer, MD, PhD*a

ABSTRACT

Background: Mas gene-related G protein-coupled receptors (MRGPRs) are a GPCR family responsive to various exogenous and endogenous agonists, playing a fundamental role in pain and itch sensation. The primate-specific family member MRGPRX2 and its murine orthologue MRGPRB2 are expressed by mast cells, mediating IgE-independent signaling and pseudo-allergic drug reactions. Objectives: Therefore, knowledge about the function and regulation of MRGPRX2/MRGPRB2 is of major importance in prevention of drug hypersensitivity reactions and drug-induced pruritus.

Methods: To identify novel MRGPR (ant)agonists, we screened a library of pharmacologically active compounds utilizing a high-throughput calcium mobilization assay. Identified hit compounds were analyzed for their pseudo-allergic and pruritogenic effects in mice and human.

Results: We found a class of commonly used drugs activating MRGPRX2 which consists to a large extent of antidepressants, antiallergic drugs, and antipsychotics. Three-dimensional pharmacophore modeling revealed structural similarities of the identified agonists, classifying them as cationic amphiphilic drugs. Mast cell activation was investigated using the three representatively selected antidepressants clomipramine, paroxetine, and desipramine. Indeed, we could show a concentration-dependent activation and MRGPRX2-dependent degranulation of the human mast cell line LAD2. Furthermore, clomipramine, paroxetine, and desipramine were able to induce degranulation of human skin and murine peritoneal mast cells. These substances elicited dose-dependent scratching behavior upon intradermal injection in C57BL/6 mice but less in MRGPRB2-mutant mice as well as wheal-and-flare reactions upon intradermal injections in humans.

Conclusion: Our results contribute to the characterization of structure-activity relationships and functionality of MRGPRX2 ligands and facilitate prediction of adverse reactions like drug induced pruritus to prevent severe drug hypersensitivity reactions.