Evidence points to the endogenous opioid system, and the muopioid receptor (MOR) in particular, in mediating the rewarding effects of drugs of abuse, including nicotine. A single nucleotide polymorphism (SNP) in the human MOR gene (OPRM1 A118G) has been shown to alter receptor protein level in preclinical models and smoking behavior in humans. To clarify the underlying mechanisms for these associations, we conducted an in vivo investigation of the effects of OPRM1 A118G genotype on MOR binding potential (BP ND or receptor availability). Twenty-two smokers prescreened for genotype (12 A/A, 10 */G) completed two [ 11 C]carfentanil positron emission tomography (PET) imaging sessions following overnight abstinence and exposure to a nicotine-containing cigarette and a denicotinized cigarette. Independent of session, smokers homozygous for the wild-type OPRM1 A allele exhibited significantly higher levels of MOR BP ND than smokers carrying the G allele in bilateral amygdala, left thalamus, and left anterior cingulate cortex. Among G allele carriers, the extent of subjective reward difference (denicotinized versus nicotine cigarette) was associated significantly with MOR BP ND difference in right amygdala, caudate, anterior cingulate cortex, and thalamus. Future translational investigations can elucidate the role of MORs in nicotine addiction, which may lead to development of novel therapeutics.genetics | neuroimaging | tobacco W ith 1 billion tobacco users worldwide, nicotine dependence has a major impact on global health. Advances in medication development for nicotine dependence require an improved understanding of the neurobiology of this complex, relapsing brain disorder (1). Although multiple neurobiological mechanisms have been implicated, a growing body of evidence points to the endogenous opioid system, and the mu-opioid receptor (MOR) in particular, in mediating the reinforcing effects of drugs of abuse, including nicotine (2-5). Nicotine upregulates MOR mRNA and protein expression in brain regions important in drug reward in rodents (4, 6) and stimulates endogenous opioid release (7,8), resulting in MOR activation and dopamine release (9).Genetic variation in MORs can modulate the endogenous opioid system, thereby altering behavior. A common single nucleotide polymorphism (SNP) in the mu-opioid receptor gene (OPRM1 A118G) results in an amino acid exchange at a putative glycosylation site in the extracellular terminus of the MOR (10). This OPRM1 SNP has been associated with a variety of drug dependence phenotypes in rodent and human studies (11), including nicotine reward, nicotine withdrawal severity, and smoking relapse (12)(13)(14).Despite substantial attention to the OPRM1 A118G in drug addiction research, the precise function of this SNP has yet to be clarified. Although the minor (G) allele was originally thought to be a "gain-of-function" variant, on the basis of increased affinity of MOR agonists (15), other data suggest that the G allele is associated with reduced mRNA and protein expression (16,17)....

Nicotine-dependence pharmacogenetics research is an emerging field, and a number of studies have begun to characterize the clinical relevance and predictive power of genetic variation in drug-metabolizing enzymes and drug target genes for response to medication. The present paper focuses on evidence for the role of nicotine-metabolizing enzymes in smoking behavior and response to treatment. Nicotine metabolism is mediated primarily by cytochrome P450 2A6 (CYP2A6). Genetic variation in the CYP2A6 gene has been linked with several smoking behavior phenotypes. Individuals who carry null or reduced activity alleles for CYP2A6 smoke fewer cigarettes per day, are less dependent on nicotine, and may have an easier time quitting smoking. A phenotypic measure of CYP2A6 enzyme activity, defined as the ratio of the nicotine metabolites 3′hydroxycotinine/cotinine, also predicts successful quitting with the transdermal nicotine patch, and counseling alone. Faster metabolizers of nicotine respond more poorly to these treatments; however, they may be excellent candidates for non-nicotine therapies, such as bupropion. Inherited variation in the CYP2B6 enzyme is also associated with response to bupropion treatment and counseling alone for smoking cessation. Inhibition of the CYP2A6 enzyme to slow nicotine metabolism is a promising approach to increase nicotine availability and potentially reduce harm from tobacco smoking.

Background Neuronal activity at gamma frequency is impaired in schizophrenia (SZ) and is considered critical for cognitive performance. Such impairments are thought to be due to reduced N-Methyl-D-Aspartate Receptor (NMDAR)-mediated inhibition from parvalbumin (PV) interneurons, rather than a direct role of impaired NMDAR signaling on pyramidal neurons. However, recent studies suggest a direct role of pyramidal neurons in regulating gamma oscillations. In particular, a computational model has been proposed in which phasic currents from pyramidal cells could drive synchronized feedback inhibition from interneurons. As such, impairments in pyramidal neuron activity could lead to abnormal gamma oscillations. However, this computational model has not been tested experimentally and the molecular mechanisms underlying pyramidal neuron dysfunction in SZ remain unclear. Methods In the present study, we tested the hypothesis that SZ-related phenotypes could arise from reduced NMDAR signaling in pyramidal neurons using forebrain pyramidal neurons specific NMDA-R1 knocked-out mice. Results The mice displayed increased baseline gamma power as well as socio-cognitive impairments. These phenotypes were associated with increased pyramidal cell excitability due to changes in inherent membrane properties. Interestingly, mutant mice showed decreased expression of GIRK2 channels, which has been linked to increase neuronal excitability. Conclusions Our data demonstrate for the first time that NMDAR hypofunction in pyramidal cells is sufficient to cause electrophysiological, molecular, neuropathological and behavioral changes related to SZ.

Idiopathic pulmonary fibrosis is a lethal parenchymal lung disease characterized by denudation of the lung epithelium, fibroblast proliferation, and collagen deposition. Cellular changes underlying disease progression involve injury to alveolar epithelial cells, epithelial to mesenchymal transition, proliferation of a-smooth muscle actin (a-SMA)-expressing myofibroblasts and of fibroblasts resulting in enhanced deposition of extracellular matrix proteins. Hepatocyte growth factor (HGF) inhibits progression of bleomycininduced pulmonary fibrosis in mice. The mechanism underlying the inhibitory effect of HGF was investigated in an in vitro model. We show that HGF markedly antagonizes basal and transforming growth factor (TGF)-b-induced expression of myofibroblast markers such as a-SMA, collagen type 1, and fibronectin in rat alveolar epithelial cells. HGF also inhibited TGF-b-induced a-SMA expression in primary murine alveolar epithelial cells. Since TGF-b is known to regulate a-SMA expression, the effect of HGF on components of TGF-b signaling was investigated. HGF induced expression of Smad7, an inhibitor of TGF-b signaling, in a mitogen-activated protein kinase-dependent manner. HGF also induced the nuclear export of Smad7 and Smad ubiquitin regulatory factor 1 (Smurf1) to the cytoplasm. HGF-dependent decrease in a-SMA was abolished with specific siRNAs targeted to Smad7. Thus, induction of Smad7 by HGF serves to limit acquisition of the myofibroblast phenotype in alveolar epithelial cells.

No abstract

Uteroglobin (UG) is an antiinflammatory protein secreted by the epithelial lining of all organs communicating with the external environment. We reported previously that UG-knockout mice manifest exaggerated inflammatory response to allergen, characterized by increased eotaxin and Th2 cytokine gene expression, and eosinophil infiltration in the lungs. In this study, we uncovered that the airway epithelia of these mice also express high levels of cyclooxygenase (COX)-2, a key enzyme for the production of proinflammatory lipid mediators, and the bronchoalveolar lavage fluid (BALF) contain elevated levels of prostaglandin D2. These effects are abrogated by recombinant UG treatment. Although it has been reported that prostaglandin D2 mediates allergic inflammation via its receptor, DP, neither the molecular mechanism(s) of DP signaling nor the mechanism by which UG suppresses DP-mediated inflammatory response are clearly understood. Here we report that DP signaling is mediated via p38 mitogen–activated protein kinase, p44/42 mitogen–activated protein kinase, and protein kinase C pathways in a cell type–specific manner leading to nuclear factor–κB activation stimulating COX-2 gene expression. Further, we found that recombinant UG blocks DP-mediated nuclear factor–κB activation and suppresses COX-2 gene expression. We propose that UG is an essential component of a novel innate homeostatic mechanism in the mammalian airways to repress allergen-induced inflammatory responses.

This study provides initial evidence for an association of the OPRM1 A118G variant with nicotine reinforcement in women.

Sulfur mustard (SM) induces vesication via poorly understood pathways. The blisters that are formed result primarily from the detachment of the epidermis from the dermis at the level of the basement membrane. In addition, there is toxicity to the basal cells, although no careful study has been performed to determine the precise mode of cell death biochemically. We describe here two potential mechanisms by which SM causes basal cell death and detachment: namely, induction of terminal differentiation and apoptosis. In the presence of 100 microM SM, terminal differentiation was rapidly induced in primary human keratinocytes that included the expression of the differentiation-specific markers K1 and K10 and the cross-linking of the cornified envelope precursor protein involucrin. The expression of the attachment protein, fibronectin, was also reduced in a time- and dose-dependent fashion. Features common to both differentiation and apoptosis were also induced in 100 microM SM, including the rapid induction of p53 and the reduction of Bcl-2. At higher concentrations of SM (i.e., 300 microM), formation of the characteristic nucleosome-sized DNA ladders, TUNEL-positive staining of cells, activation of the cysteine protease caspase-3/apopain, and cleavage of the death substrate poly(ADP-ribose) polymerase, were observed both in vivo and in vitro. Both the differentiation and the apoptotic processes appeared to be calmodulin dependent, because the calmodulin inhibitor W-7 blocked the expression of the differentiation-specific markers, as well as the apoptotic response, in a concentration-dependent fashion. In addition, the intracellular Ca2+ chelator, BAPTA-AM, blocked the differentiation response and attenuated the apoptotic response. These results suggest a strategy for designing inhibitors of SM vesication via the Ca2+-calmodulin or caspase-3/PARP pathway.