Inhibitory Effect Of Nicotine Research Articles

Ascorbic acid mitigates the deleterious effects of nicotine on tendon stem cells

ABSTRACT Purpose: Nicotine causes tendon degeneration, whereas ascorbic acid imparts beneficial effects on tendon cells. Tendon stem cells (TSCs) play a vital role in maintaining tissue integrity and promoting restoration of structure and function after tendon injury. In the present study, cell culture experiments were performed to determine the effects of nicotine on TSCs and whether ascorbic acid supplementation could antagonize the action of high concentration nicotine. Methods: After treatment with nicotine and ascorbic acid, TSC proliferation, migration, stemness, apoptosis, and differentiation were analyzed. Results: TSC proliferation and expression of stem cell markers were significantly impaired by a high concentration of nicotine (1000 ng/mL), but a lower concentration (100 ng/mL) induced proliferative effects in TSCs. Moreover, the highest concentration of nicotine tested (1000 ng/mL) significantly inhibited the migratory ability of TSCs, while relatively high concentrations (100 and 1000 ng/mL) significantly (p < 0.05) up-regulated non-tenocyte genes. When ascorbic acid was added, the inhibitory effects of nicotine on the proliferation, migration, and stemness of TSCs were reversed. In addition, flow cytometry analysis showed that these nicotine concentrations could induce cell apoptosis, while the addition of ascorbic acid inhibited apoptosis. Conclusion: Addition of ascorbic acid partially reversed the inhibitory effect of a high concentration of nicotine. These findings indicate that while nicotine impairs the biological characteristics of TSCs, ascorbic acid can mitigate these deleterious effects and, therefore, may be useful for decreasing nicotine-induced tendon degeneration.

Investigation of feeding behaviour in C. elegans reveals distinct pharmacological and antibacterial effects of nicotine

Caenorhabditis elegans is an informative model to study the neural basis of feeding. A useful paradigm is one in which adult nematodes feed on a bacterial lawn which has been pre-loaded with pharmacological agents and the effect on pharyngeal pumping rate scored. A crucial aspect of this assay is the availability of good quality bacteria to stimulate pumping to maximal levels. A potential confound is the possibility that the pharmacological agent impacts bacterial viability and indirectly influences feeding rate. Here, the actions of nicotine on pharyngeal pumping of C. elegans and on the Escherichia coli bacterial food source were investigated. Nicotine caused an immediate and concentration-dependent inhibition of C. elegans pharyngeal pumping, IC50 4 mM (95% CI = 3.4 mM to 4.8 mM). At concentrations between 5 and 25 mM, nicotine also affected the growth and viability of E. coli lawns. To test whether this food depletion by nicotine caused the reduced pumping, we modified the experimental paradigm. We investigated pharyngeal pumping stimulated by 10 mM 5-HT, a food ‘mimic’, before testing if nicotine still inhibited this behaviour. The IC50 for nicotine in these assays was 2.9 mM (95% CI = 3.1 mM to 5.1 mM) indicating the depletion of food lawn does not underpin the potency of nicotine at inhibiting feeding. These studies show that the inhibitory effect of nicotine on C. elegans pharyngeal pumping is mediated by a direct effect rather than by its poorly reported bactericidal actions.

SOCS3 participates in cholinergic pathway regulation of synovitis in rheumatoid arthritis

ABSTRACTStimulation of the cholinergic inflammatory pathway can attenuate collagen-induced arthritis (CIA) and inhibit synovitis by Janus kinase (JAK) 2 and signal transducer and activator of transcription (STAT) 3 signaling. Suppressor of cytokine signaling (SOCS) protein can also regulate the inflammatory processes and activate JAK/STAT signal transduction, but its involvement in rheumatoid arthritis (RA) has not been demonstrated. This study investigated the effect of SOCS on cholinergic pathway regulation of synovitis in the fibroblast-like synoviocytes (FLSs) of RA and CIA mice. The effects of nicotine on SOCS1 and SOCS3 protein expression in FLSs were assayed by western blotting before and after transfection with a small interfering RNA oligonucleotide (SOCS3-siRNA or control-siRNA). Interleukin-6 was measured by enzyme-linked immunosorbent assay of SOCS3-siRNA and control-siRNA transfected FLS culture supernatants. Histopathological evaluation and immunohistochemical staining of SOCS3 were performed in joint tissue sections of control, CIA model, vagotomy, and nicotine-treated DBA/1 mice. Nicotine increased SOCS3 expression in the FLSs of RA. The inhibitory effect of nicotine on inflammatory factors was abolished by siRNA knockdown of SOCS3 protein expression. Nicotine increased the expression of SOCS3 protein in the synovium and reduced synovitis and bone erosion in CIA mice.

Nicotine induces TIPE2 upregulation and Stat3 phosphorylation contributes to cholinergic anti-inflammatory effect.

Cholinergic anti-inflammatory pathway has therapeutic effect on inflammation-associated diseases. However, the exact mechanism of nicotine-mediated anti-inflammatory effect is still unclear. TIPE2, a new member of tumor necrosis factor-α-induced protein-8 family, is a negative regulator of immune homeostasis. However, the roles of TIPE2 in cholinergic anti-inflammatory effect are still uncertain. Here, we demonstrated that nicotine exerts its anti-inflammatory effect by TIPE2 upregulation and phosphorylated stat3 mediated the inhibition of NF-κB activation, which was supported by the following evidence: firstly, both nicotine and TIPE2 inhibit pro-inflammatory cytokine release via NF-κB inactivation. Secondly, nicotine upregulates TIPE2 expression via α7 nicotinic acetylcholine receptor. Moreover, the enhancement of stat3 phosphorylation and decrease of LPS-induced p65 translocation were achieved by nicotine treatment. Importantly, nicotine treatment augments the interaction of phosphorylated stat3 and p65, indicating that the inhibitory effect of nicotine on NF-κB activation was mediated with protein-protein interactions. Hence, this study revealed that TIPE2 upregulation and stat3 phosphorylation contribute to nicotine-mediated anti-inflammation effect, indicating that TIPE2 and stat3 might be potential molecules for dealing with inflammation-associated diseases.

Nicotine Suppressed Fetal Adrenal StAR Expression via YY1 Mediated-Histone Deacetylation Modification Mechanism.

Steroidogenic acute regulatory (StAR) protein plays a pivotal role in steroidogenesis. Previously, we have demonstrated that prenatal nicotine exposure suppressed fetal adrenal steroidogenesis via steroidogenic factor 1 deacetylation. This study further explored the potential role of the transcriptional repressor Yin Yang 1 (YY1) in nicotine-mediated StAR inhibition. Nicotine was subcutaneously administered (1.0 mg/kg) to pregnant rats twice per day and NCI-H295A cells were treated with nicotine. StAR and YY1 expression were analyzed by real-time PCR, immunohistochemistry, and Western blotting. Histone modifications and the interactions between the YY1 and StAR promoter were assessed using chromatin immunoprecipitation (ChIP). Prenatal nicotine exposure increased YY1 expression and suppressed StAR expression. ChIP assay showed that there was a decreasing trend for histone acetylation at the StAR promoter in fetal adrenal glands, whereas H3 acetyl-K14 at the YY1 promoter presented an increasing trend following nicotine exposure. Furthermore, in nicotine-treated NCI-H295A cells, nicotine enhanced YY1 expression and inhibited StAR expression. ChIP assay showed that histone acetylation decreased at the StAR promoter in NCI-H295A cells and that the interaction between the YY1 and StAR promoter increased. These data indicated that YY1-medicated histone deacetylation modification in StAR promoters might play an important role in the inhibitory effect of nicotine on StAR expression.

A mechanism-based study on inhibitory effect of nicotine and cotinine on human lactate dehydrogenase C

Lactate dehydrogenase C (LDHC) as the most abundant isoform of lactate dehydrogenase in testis and spermatozoa, has a critical role in energy metabolism of germ cells. Also, LDHC gene is expressed aberrantly with a high prevalence in various kinds of malignancies. So, LDHC is a promising target protein for development of contraceptive and anti-cancer drugs. In the current study, inhibitory effects of nicotine and cotinine on human LDHC were investigated. Partially purified LDHC was extracted from healthy human spermatozoa and treated with various concentrations of nicotine and cotinine at a range of 0.13-0.66 μM. The results showed that at a concentration of 0.6 μM, cotinine and nicotine could inhibit LDHC activity by 47% and 45%, respectively. Mechanisms of these inhibitory effects were further investigated by docking and molecular dynamic (MD) simulation studies. Nicotine and cotinine were docked against available crystal structure of mice LDHC (PDB ID: 2LDX). LDHC alone and in complex with docked ligands was minimized, solvated in explicit water cage, neutralized by addition of required ions, and finally simulated for 50 ns of MD simulation. Analysis of simulated structures revealed that nicotine and cotinine could affect LDHC structure near His192 which play a key role in the interaction of LDHC with pyruvate/lactate. Thus, it seems that nicotine and cotinine could induce their effects via an inhibitory competition mechanism. Enzymatic assays with various concentration of pyruvate in the presence of mean plasma concentration of nicotine and cotinine in active smokers confirmed MD simulation results.

Pharmacological Beta-Adrenergic Receptor Activation Attenuates Neutrophil Recruitment by a Mechanism Dependent on Nicotinic Receptor and the Spleen.

The aim of this study was to identify the effect of beta-adrenergic receptor activation on neutrophil migration in experimental peritonitis elucidating the neuroimmune components involved such as nicotinic receptors and the spleen. Mice pre-treated with mecamylamine (nicotinic antagonist) and propranolol (beta-adrenergic antagonist) or splenectomized animals were treated with isoproterenol (beta-adrenergic agonist) prior to intraperitoneal injection of carrageenan. After 4h, the infiltrating neutrophils and the local cytokine/chemokine levels were evaluated in the peritoneal lavage. The effect of isoproterenol on neutrophil chemotaxis was investigated in a Boyden chamber. Isoproterenol inhibited neutrophil trafficking, reducing the cytokine/chemokine release and neutrophil chemotaxis. Surprisingly, the isoproterenol effect on neutrophil migration was totally reverted by splenectomy and mecamylamine pre-treatment. In contrast, the inhibitory effect of nicotine on neutrophil migration was abrogated only by splenectomy but not by propranolol pre-treatment. Collectively, our data show that beta-adrenergic receptor activation regulates the acute neutrophil recruitment via splenic nicotinic receptor.

Nicotine inhibits activation of microglial proton currents via interactions with \u03b17 acetylcholine receptors

Alpha 7 subunits of nicotinic acetylcholine receptors (nAChRs) are expressed in microglia and are involved in the suppression of neuroinflammation. Over the past decade, many reports show beneficial effects of nicotine, though little is known about the mechanism. Here we show that nicotine inhibits lipopolysaccharide (LPS)-induced proton (H+) currents and morphological change by using primary cultured microglia. The H+ channel currents were measured by whole-cell patch clamp method under voltage-clamp condition. Increased H+ current in activated microglia was attenuated by blocking NADPH oxidase. The inhibitory effect of nicotine was due to the activation of α7 nAChR, not a direct action on the H+ channels, because the effects of nicotine was cancelled by α7 nAChR antagonists. Neurotoxic effect of LPS-activated microglia due to inflammatory cytokines was also attenuated by pre-treatment of microglia with nicotine. These results suggest that α7 nAChRs in microglia may be a therapeutic target in neuroinflammatory diseases.

Mo1689 Nicotine Significantly Affects the Expression of Vascular Endothelial Adhesion Molecules and Ameliorates DSS Induced Colitis

Introduction Anti-adhesion molecule therapy is useful for inflammatory bowel diseases. Smoking has been reported to have a harmful effect on Crohn's disease, but it is still controversial in ulcerative colitis. Although effect of nicotine on adhesion molecules of cardiovascular system has been well recognized, it has not been studied in the intestine. We investigated effect of nicotine on murine colitis induced by dextran sodium sulfate (DSS) and compared expression of adhesion molecules in vitro in several conditions including preconditioning exposure. Involvement of nicotinic acetylcholine receptor (nAChR) was also examined. Method In in vivo study C57BL/6J mice were treated with 3% DSS and 0.1mg/ ml nicotine in drinking water for 7 days. Disease activity of colitis was assessed by DAI score. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in colonic tissues were measured by qPCR. Microvascular endothelial cell line, bEnd3, was used for in vitro study. The cultured cells (2x105/ml) were treated with 5ng/ml TNF-α and 200μg/ml nicotine for 12 hours. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in cells were measured by qPCR. Various concentrations of nicotine (0.01-1000μM) were tested. In pre-treatment protocol, cells were treated with nicotine for 3 days, and after 12 hours interval without nicotine, exposed to TNF-α and nicotine for 12 hours as treatment. In some experiments cells were cultured with TNF-α and nicotine under the presence of 0.01μM mecamylamine (Meca, nonselective nAChR antagonist) or 0.01μM methyllycaconitine (MLA, selective α7nAChR antagonist). Result In in vivo study, nicotine treatment decreased DAI score induced by DSS. Although nicotine alone did not affect expression of ICAM-1, VCAM-1 and MAdCAM-1 in control mice, addition of nicotine to DSS mice significantly attenuated the increased expression of VCAM-1 and MAdCAM-1 induced by DSS, and tended to inhibit ICAM-1. In in vitro study, expression of ICAM-1, VCAM-1 and MAdCAM-1 was increased by TNF-α. Increased expression of MAdCAM-1 was significantly attenuated by simultaneous administration of nicotine. In dose-response study, degree of ICAM-1 inhibition by nicotine was only observed at high doses, whereas that of MAdCAM-1 was observed in a low dose already. Interestingly pretreatment with nicotine before TNF-α decreased inhibitory effect of nicotine. These inhibitory effects tended to be attenuated by Meca or MLA, but not

Mo1690 Serotonin/5-HT3 Receptor and Substance P/NK1 Receptor Pathways Contribute to the Pathogenesis of Colonic Inflammation in Mice

Introduction Anti-adhesion molecule therapy is useful for inflammatory bowel diseases. Smoking has been reported to have a harmful effect on Crohn's disease, but it is still controversial in ulcerative colitis. Although effect of nicotine on adhesion molecules of cardiovascular system has been well recognized, it has not been studied in the intestine. We investigated effect of nicotine on murine colitis induced by dextran sodium sulfate (DSS) and compared expression of adhesion molecules in vitro in several conditions including preconditioning exposure. Involvement of nicotinic acetylcholine receptor (nAChR) was also examined. Method In in vivo study C57BL/6J mice were treated with 3% DSS and 0.1mg/ ml nicotine in drinking water for 7 days. Disease activity of colitis was assessed by DAI score. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in colonic tissues were measured by qPCR. Microvascular endothelial cell line, bEnd3, was used for in vitro study. The cultured cells (2x105/ml) were treated with 5ng/ml TNF-α and 200μg/ml nicotine for 12 hours. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in cells were measured by qPCR. Various concentrations of nicotine (0.01-1000μM) were tested. In pre-treatment protocol, cells were treated with nicotine for 3 days, and after 12 hours interval without nicotine, exposed to TNF-α and nicotine for 12 hours as treatment. In some experiments cells were cultured with TNF-α and nicotine under the presence of 0.01μM mecamylamine (Meca, nonselective nAChR antagonist) or 0.01μM methyllycaconitine (MLA, selective α7nAChR antagonist). Result In in vivo study, nicotine treatment decreased DAI score induced by DSS. Although nicotine alone did not affect expression of ICAM-1, VCAM-1 and MAdCAM-1 in control mice, addition of nicotine to DSS mice significantly attenuated the increased expression of VCAM-1 and MAdCAM-1 induced by DSS, and tended to inhibit ICAM-1. In in vitro study, expression of ICAM-1, VCAM-1 and MAdCAM-1 was increased by TNF-α. Increased expression of MAdCAM-1 was significantly attenuated by simultaneous administration of nicotine. In dose-response study, degree of ICAM-1 inhibition by nicotine was only observed at high doses, whereas that of MAdCAM-1 was observed in a low dose already. Interestingly pretreatment with nicotine before TNF-α decreased inhibitory effect of nicotine. These inhibitory effects tended to be attenuated by Meca or MLA, but not

Peripheral alpha4beta2 nicotinic acetylcholine receptor signalling attenuates tactile allodynia and thermal hyperalgesia after nerve injury in mice.

Neuropathic pain is often refractory to conventional analgesics including opioids and non-steroidal anti-inflammatory drugs. Evidence suggests nicotinic acetylcholine receptor ligands regulate pain transmission. Effects of α4β2 nicotinic acetylcholine receptor activation on pain behaviours after nerve injury were studied. Mice were subjected to partial sciatic nerve ligation (PSL). Nicotinic acetylcholine receptor α4 and β2 subunits localization in injured nerves were evaluated by immunohistochemistry. Neuropathic pain, assessed by tactile allodynia and thermal hyperalgesia, was examined by von Frey test and Hargreaves test respectively. Nicotinic acetylcholine receptor α4 and β2 subunits were up-regulated in injured nerves and were expressed on F4/80-positive macrophages. When nicotine was perineurally administered daily for 4 days (day 7-10; maintenance phase) after nerve injury, pain behaviours were significantly alleviated. The inhibitory effects of nicotine were reversed by co-administration of mecamylamine (non-selective nicotinic acetylcholine receptor antagonist) and dihydro-β-erythroidine (selective α4β2 nicotinic acetylcholine receptor antagonist). Likewise, when α4β2 nicotinic acetylcholine receptor agonists (TC2559 or ABT418) were administered daily for 4 days (day 7-10) after nerve injury, pain behaviours were significantly attenuated. On the other hand, nicotine administered daily for 4 days (day 0-3; initiation phase) after nerve injury alleviated pain behaviours, which were antagonized by co-administration of dihydro-β-erythroidine. TC2559 administered daily for 4 days (day 0-3) also attenuated nerve injury-induced pain behaviours. The activation of α4β2 nicotinic acetylcholine receptor expressed on infiltrating macrophages in injured nerves may participate in the relief of PSL-induced neuropathic pain during maintenance and initiation phases.

The Inhibitory Effect of Nicotine against Staphylococcus Aureus and Escherichia Coli

The main objective of the study was to determine the antibacterial effect of nicotine against the Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Specifically, it determined the bacterium that is resistant and susceptible in nicotine and the significant difference in the inhibitory effect of Nicotine on E. coli and S. aureus . Experimental design was used subjecting both bacteria to the nicotine extract, and their susceptibility was measured by the diameter of the zone of inhibition in millimeter. The finding revealed that S. aureus is found to be susceptible to nicotine extract. On the other hand, the extract has an intermediate effect on E. coli . Hence, nicotine can be further studied for its medicinal property. Moreover, there is a significant difference in the inhibitory effect of nicotine against S. aureus and E. coli . Thus, the null hypothesis is rejected. Â Keywords: Nicotine, antibacterial effect, Staphylococcus aureus , Escherichia coli

Unusual Effects of Nicotine as a Psychostimulant on Ambulatory Activity in Mice

The present study examined the effect of nicotine, alone and in combination with various drugs that act on the CNS, on ambulatory activity, a behavioral index for locomotion, in ICR (CD-1) strain mice. Nicotine at 0.25–2 mg/kg acutely reduced ambulatory activity of ICR mice. The effect of nicotine was similar to that of haloperidol and fluphenazine but distinct from that of bupropion and methylphenidate. ICR mice developed tolerance against the inhibitory effect of nicotine on ambulatory activity when nicotine was repeatedly administered. This effect was also distinct from bupropion and methylphenidate as they produced augmentation of their ambulation-stimulating effects in ICR mice. Nicotine reduced the ambulation-stimulating effects of bupropion and methylphenidate as well as haloperidol and fluphenazine. Taken together, nicotine exhibited unusual effects as a psychostimulant on ambulatory activity in ICR mice.

Potential Contribution of Aromatase Inhibition to the Effects of Nicotine and Related Compounds on the Brain

Cigarette smoking continues to be a major public health problem, and while smoking rates in men have shown some decrease over the last few decades, smoking rates among girls and young women are increasing. Practically all of the important aspects of cigarette smoking and many effects of nicotine are sexually dimorphic (reviewed by Pogun and Yararbas, 2009). Women become addicted more easily than men, while finding it harder to quit. Nicotine replacement appears to be less effective in women. This may be linked to the observation that women are more sensitive than men to non-nicotine cues or ingredients in cigarettes. The reasons for these sex differences are mostly unknown. Several lines of evidence suggest that many of the reported sex differences related to cigarette smoking may stem from the inhibitory effects of nicotine and other tobacco alkaloids on estrogen synthesis via the enzyme aromatase (cyp19a gene product). Aromatase is the last enzyme in estrogen biosynthesis, catalyzing the conversion of androgens to estrogens. This review provides a summary of experimental evidence supporting brain aromatase as a potential mediator and/or modulator of nicotine actions in the brain, contributing to sex differences in smoking behavior. Additional research on the interaction between tobacco smoke, nicotine, and aromatase may help devise new, sex specific methods for prevention and treatment of smoking addiction.

Positive RAR/RXR and Negative STAT3 Regulation of FOXP3 Transcription is Mediated by Control of SMAD3 Access and Binding to an Enhancer

Some clinical trials and epidemiologic studies revealed improvements in symptoms of ulcerative colitis after smoking and nicotine patch treatment. However, mechanisms underlying the ameliorating effect of nicotine remain poorly understood. We have previously reported that nicotine administration ameliorates murine oxazolone (OXZ)-induced colitis through alpha7 nicotine acetylcholine receptors (α7nAChRs). In addition, we have shown that mRNA of α7nAChRs was expressed in plasmacytoid dendritic cells (pDCs) of OXZ colitis mouse colon. The aim of this study was to investigate a pathophysiological role of pDCs and immunological effects of nicotine on pDCs in ulcerative colitis. Method: OXZ-induced colitis was developed in BALB/c mice. Lamina propria mononuclear cells (LPMCs) of the colon and mesenteric lymph node (MLN) were collected in OXZ colitis mice. pDCs were isolated from LPMCs by using magnetic cell separation system (BD biosciences). In addition, mouse bone marrow (BM) cells were differentiated to pDC-like cells (BMpDC) by Flt3 ligand. Furthermore, immunological effects of nicotine on BMpDCwere examined by flow cytometry and BMpDC migration was examined by chemotaxis assay using EZ-TAXIScan. Moreover, the effect of nicotine administration on pDC subset proportion was investigated in the MLN of OXZ colitis mice. Result: α7nAChRs mRNA was expressed in pDC of OXZ colitis mouse colon and BMpDC, but not BM conventional dendritic cells (cDC). Flow cytometry analysis revealed that neither CD80, CD86 nor MHC class II expression in BMpDC was affected with nicotine in the induction of pDC maturation by CpG-DNA. On the other hand, CCL21induced migration of mature BMpDC was inhibited by nicotine and α7nAChRs selective agonist GTS-21, and α7nAChRs selective antagonist methyllycaconitine (MLA) blocked the inhibitory effect of nicotine and GTS-21. Furthermore, nicotine administration downregulated pDC subset proportion in the MLN of OXZ colitis mice. Conclusion: These data suggest that the activation of α7nAChRs reduces pDC-mediated antigen presentation to naive CD4 T cells by inhibiting pDC migration from colon to MLN, thereby alleviating the symptoms in OXZ colitis. Our results may contribute to the development of therapeutic medicines for ulcerative colitis by activating the cholinergic anti-inflammatory pathway.

Nicotine Improves Symptoms in Murine Oxazolone-Induced Ulcerative Colitis by Inhibiting Migration of Plasmacytoid Dendritic Cells Through Alpha7 Nicotinic Acetylcholine Receptors

Some clinical trials and epidemiologic studies revealed improvements in symptoms of ulcerative colitis after smoking and nicotine patch treatment. However, mechanisms underlying the ameliorating effect of nicotine remain poorly understood. We have previously reported that nicotine administration ameliorates murine oxazolone (OXZ)-induced colitis through alpha7 nicotine acetylcholine receptors (α7nAChRs). In addition, we have shown that mRNA of α7nAChRs was expressed in plasmacytoid dendritic cells (pDCs) of OXZ colitis mouse colon. The aim of this study was to investigate a pathophysiological role of pDCs and immunological effects of nicotine on pDCs in ulcerative colitis. Method: OXZ-induced colitis was developed in BALB/c mice. Lamina propria mononuclear cells (LPMCs) of the colon and mesenteric lymph node (MLN) were collected in OXZ colitis mice. pDCs were isolated from LPMCs by using magnetic cell separation system (BD biosciences). In addition, mouse bone marrow (BM) cells were differentiated to pDC-like cells (BMpDC) by Flt3 ligand. Furthermore, immunological effects of nicotine on BMpDCwere examined by flow cytometry and BMpDC migration was examined by chemotaxis assay using EZ-TAXIScan. Moreover, the effect of nicotine administration on pDC subset proportion was investigated in the MLN of OXZ colitis mice. Result: α7nAChRs mRNA was expressed in pDC of OXZ colitis mouse colon and BMpDC, but not BM conventional dendritic cells (cDC). Flow cytometry analysis revealed that neither CD80, CD86 nor MHC class II expression in BMpDC was affected with nicotine in the induction of pDC maturation by CpG-DNA. On the other hand, CCL21induced migration of mature BMpDC was inhibited by nicotine and α7nAChRs selective agonist GTS-21, and α7nAChRs selective antagonist methyllycaconitine (MLA) blocked the inhibitory effect of nicotine and GTS-21. Furthermore, nicotine administration downregulated pDC subset proportion in the MLN of OXZ colitis mice. Conclusion: These data suggest that the activation of α7nAChRs reduces pDC-mediated antigen presentation to naive CD4 T cells by inhibiting pDC migration from colon to MLN, thereby alleviating the symptoms in OXZ colitis. Our results may contribute to the development of therapeutic medicines for ulcerative colitis by activating the cholinergic anti-inflammatory pathway.

Influence of nicotine on the biological activity of rabbit osteoblasts

To assess the influence of nicotine on the proliferation and gene expression of osteogenic and angiogenic mediators of osteoblasts. Rabbit primary osteoblasts were exposed to various concentrations of nicotine (0.001, 0.1 and 10 μmol/l). The cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The gene expression of transforming growth factor (TGF)-β(1), bone morphogenetic protein (BMP)-2, platelet-derived growth factor (PDGF)-AA and vascular endothelial growth factor (VEGF) was evaluated using real-time reverse transcription - polymerase chain reaction. The osteoblast proliferation was inhibited by nicotine at the concentration of 0.001-10 μM at 48 and 72 h of culture, but with no significant effect at 24 h. The expression of TGF-β(1), BMP-2, PDGF-AA and VEGF was inhibited by nicotine at the concentrations of 0.1 and 10 μM, but with no significant difference at the low concentration of 0.001 μM. Nicotine suppresses osteoblast proliferation and inhibits the expression of some key osteogenic and angiogenic mediators in the in vitro experimental model. These inhibitory effects of nicotine on the osteoblast activity may reflect, to a certain degree, the overall detrimental effects of tobacco use on the survival rate of dental implants.

Nicotine Reduces TNF-α Expression Through a α7 nAChR/MyD88/NF-ĸB Pathway in HBE16 Airway Epithelial Cells

Aims: To explore the signaling mechanism associated with the inhibitory effect of nicotine on tumor necrosis factor (TNF)- α expression in human airway epithelial cells. Methods: HBE16 airway epithelial cells were cultured and incubated with either nicotine or cigarette smoke extract (CE). Cells were then transfected with α1, α5, or α7 nicotinic acetylcholine receptor (nAChR)-specific small interfering RNAs (siRNAs). The effects of nicotine on the production of proinflammatory factors TNF-α, in transfected cells were analyzed. Furthermore, we assayed the expression levels of myeloid differentiation primary response gene 88 (MyD88) protein, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) p65 protein, NF-ĸB activity and NF-ĸB inhibitor alpha (I-ĸBα) expression in cells after treatment with nicotine or α7 nAChR inhibitor, α -bungarotoxin (α-BTX). Results: The production of TNF-α was lower in cells pretreated with nicotine before lipopolysaccharide (LPS) stimulation, compared with LPS-only-treated cells. In contrast, in α7 siRNA-transfected cells incubated with nicotine and LPS, TNF-α expression was higher than that in non-transfected cells or in α1 or α5 siRNA-transfected cells. Addition of MyD88 siRNA or the NF-ĸB inhibitor pyridine-2,6-dithiocarboxylic acid (PDTC) also reduced TNF-α expression. Furthermore, we found that nicotine decreased MyD88 protein, NF-ĸB p65 protein, NF-ĸB activity and phospho-I-ĸBα expression induced by CE or LPS. The inhibitor α-BTX could reverse these effects. Conclusion: Nicotine reduces TNF-α expression in HBE16 airway epithelial cells, mainly through an α7 nAChR/MyD88/NF-ĸB pathway.

Corrections to: “Harte C, Meston CM. The inhibitory effects of nicotine on physiological sexual arousal in nonsmoking women: Results from a randomized, double-blind, placebo-controlled cross-over trial. J Sex Med 2008;5:1184–97.”

Corrections to: “Harte C, Meston CM. The inhibitory effects of nicotine on physiological sexual arousal in nonsmoking women: Results from a randomized, double-blind, placebo-controlled cross-over trial. J Sex Med 2008;5:1184–97.”

The Lateral Paragigantocellular Nucleus Modulates Parasympathetic Cardiac Neurons: A Mechanism for Rapid Eye Movement Sleep-Dependent Changes in Heart Rate

Rapid eye movement (REM) sleep is generally associated with a withdrawal of parasympathetic activity and heart rate increases; however, episodic vagally mediated heart rate decelerations also occur during REM sleep. This alternating pattern of autonomic activation provides a physiological basis for REM sleep-induced cardiac arrhythmias. Medullary neurons within the lateral paragigantocellular nucleus (LPGi) are thought to be active after REM sleep recovery and play a role in REM sleep control. In proximity to the LPGi are parasympathetic cardiac vagal neurons (CVNs) within the nucleus ambiguus (NA), which are critical for controlling heart rate. This study examined brain stem pathways that may mediate REM sleep-related reductions in parasympathetic cardiac activity. Electrical stimulation of the LPGi evoked inhibitory GABAergic postsynaptic currents in CVNs in an in vitro brain stem slice preparation in rats. Because brain stem cholinergic mechanisms are involved in REM sleep regulation, we also studied the role of nicotinic neurotransmission in modulation of GABAergic pathway from the LGPi to CVNs. Application of nicotine diminished the GABAergic responses evoked by electrical stimulation. This inhibitory effect of nicotine was prevented by the alpha7 nicotinic receptor antagonist alpha-bungarotoxin. Moreover, hypoxia/hypercapnia (H/H) diminished LPGi-evoked GABAergic current in CVNs, and this inhibitory effect was also prevented by alpha-bungarotoxin. In conclusion, stimulation of the LPGi evokes an inhibitory pathway to CVNs, which may constitute a mechanism for the reduced parasympathetic cardiac activity and increase in heart rate during REM sleep. Inhibition of this pathway by nicotinic receptor activation and H/H may play a role in REM sleep-related and apnea-associated bradyarrhythmias.