The voltage-gated sodium channel NaV1.8 blocker A-803467 inhibits cough in the guinea pig.

Cough in respiratory diseases is attributed to the activation of airway C-fibers by inflammation. Inflammatory mediators can act on multiple receptors expressed in airway C-fibers, nonetheless, the action potential initiation in C-fibers depends on a limited number of voltage-gated sodium channel (NaV1) subtypes. We have recently demonstrated that NaV1.8 substantially contributes to the action potential initiation in the airway C-fiber subtype implicated in cough. We therefore hypothesized that the NaV1.8 blocker A-803467 inhibits cough. We evaluated the cough evoked by the inhalation of C-fiber activator capsaicin in awake guinea pigs. Compared to vehicle, intraperitoneal or inhaled A-803467 caused 30-50% inhibition of cough at the doses that did not alter respiratory rate. We conclude that the NaV1.8 blocker A-803467 inhibits cough in a manner consistent with its action on the C-fiber nerve terminals in the airways. Targeting voltage-gated sodium channels mediating action potential initiation in airway C-fibers may offer a means of cough inhibition that is independent of the stimulus.

Neuropeptide Y signaling in the dorsal raphe nucleus inhibits male sexual behavior in mice.

Animals change their biological activities depending on their nutritional state. Reproductive functions, including sexual behavior, are suppressed under low-energy conditions; however, the underlying neuronal mechanism is poorly understood. Neuropeptide Y (NPY) is an orexigenic molecule released in response to low-energy conditions and has an inhibitory effect on sexual behavior. We examined how NPY is involved in energy state-dependent regulation of male sexual behavior. Mounting, intromission, and ejaculation were evaluated as parameters of sexual behavior. Almost all parameters indicated that fasting for 24h suppressed male sexual behavior. Intracerebroventricular injection of NPY inhibited sexual behavior in males that free-fed for 8h following 24-h fasting (fed males). We next examined whether the dorsal raphe nucleus (DRN), in which serotonergic (5-HT) neurons are distributed, is involved in NPY-mediated inhibition of male sexual behavior. NPY-positive processes immunoreactive for a presynaptic marker, synaptophysin, were distributed in the DRN of both fed and fasted males. Expression of the NPY Y1 receptor in 5-HT neurons was also observed. Direct injection of NPY or 8-OH-DPAT (a 5-HT1A receptor agonist that inhibits the activity of 5-HT neurons) into the DRN inhibited male sexual behavior in fed males. In contrast, injection of BIBP-3226, a NPY Y1 receptor antagonist, or (+)-DOI hydrochloride (DOI), a 5-HT2A/2C receptor agonist that activates 5-HT neurons, into the DRN partially recovered male sexual behavior in 24-h fasted males. These results suggest that NPY inhibits serotonergic neuronal activity via the Y1 receptor in the DRN, resulting in suppression of male sexual behavior in low-energy conditions.

Prolonged matrix metalloproteinase-3 high expression after cyclic compressive load on human synovial cells in three-dimensional cultured tissue.

Excessive mechanical stress is thought to be a factor in the development of joint disorders through the expression of matrix metalloproteinases (MMPs) and related cytokines. Although studies revealed that mechanical stress on the synovium induces MMP expression, it is still not known which MMPs prolonged high level expression. The authors focused on MMP-3, which is one of the major factors in joint disorders such as rheumatism and temporomandibular joint disorders. They examined mRNA and protein levels of MMP-3, other MMPs and related cytokines after loading stress. Human synovial cells were seeded onto a collagen scaffold and different magnitudes of cyclic compressive load were applied for 1h. Time-dependent mRNA and protein levels for catabolic genes were examined after loading. mRNA expressions of MMP-1, MMP-3, MMP-9, IL-6, IL-8 and IL-1ß increased after excessive compression. In particular, only mRNA of MMP-3 was up-regulated and maintained at a high level for 24h after excessive loading. The concentrations of MMP-3, IL-6 and IL-8 in culture media after loading increased with excessive compression. These results may account for the pathomechanism of MMP-3 induced by cyclic load on synovial cells in joint disorders.

Transgene expression and effective gene silencing in vagal afferent neurons in vivo using recombinant adeno-associated virus vectors.

Vagal afferent fibres innervating thoracic structures such as the respiratory tract and oesophagus are diverse, comprising several subtypes of functionally distinct C-fibres and A-fibres. Both morphological and functional studies of these nerve subtypes would be advanced by selective, effective and long-term transduction of vagal afferent neurons with viral vectors. Here we addressed the hypothesis that vagal sensory neurons can be transduced with adeno-associated virus (AAV) vectors in vivo, in a manner that would be useful for morphological assessment of nerve terminals, using enhanced green fluorescent protein (eGFP), as well as for the selective knock-down of specific genes of interest in a tissue-selective manner. We found that a direct microinjection of AAV vectors into the vagal nodose ganglia in vivo leads to selective, effective and long-lasting transduction of the vast majority of primary sensory vagal neurons without transduction of parasympathetic efferent neurons. The transduction of vagal neurons by pseudoserotype AAV2/8 vectors in vivo is sufficiently efficient such that it can be used to functionally silence TRPV1 gene expression using short hairpin RNA (shRNA). The eGFP encoded by AAV vectors is robustly transported to both the central and peripheral terminals of transduced vagal afferent neurons allowing for bright imaging of the nerve endings in living tissues and suitable for structure-function studies of vagal afferent nerve endings. Finally, the AAV2/8 vectors are efficiently taken up by the vagal nerve terminals in the visceral tissue and retrogradely transported to the cell body, allowing for tissue-specific transduction.

Effects of compressive loading on human synovium-derived cells.

Compressive stress may be involved in temporomandibular joint (TMJ) synovitis, but its mechanism has not been fully elucidated. We hypothesized that mechanical stress to the synovial cells of the TMJ potentially causes degenerative changes in temporomandibular joint disease. We examined the effect of cyclic compressive loading on three-dimensionally engineered constructs using human TMJ synovium-derived cells in vitro. Human TMJ synovium-derived cells were cultured onto collagen scaffolds, resulting in three-dimensional constructs. Cyclic compression loading was applied to the constructs by means of a custom-designed apparatus. DNA amount, apoptotic cells, and mRNA levels for inflammatory cytokines were analyzed. The protein expression and activity of MMPs were examined. DNA amount or apoptotic cell number was unchanged by loading. MMP-2, -3, and IL-8 mRNA expression was up-regulated by the compression, and both MMP-1 and -3 protein expression and MMP-2 activity were detected. Thus, compression of human TMJ synovium-derived cells appears to modulate inflammatory cytokines.

Volatile female odors activate the accessory olfactory system of male mice without physical contact.

We previously reported that male mice are more attracted to volatile odors from intact female mice than from ovariectomized female mice. In the present study, we investigated male attraction to volatile odors from soiled bedding collected from the cages of estrous or ovariectomized female mice. There was no difference in the total time spent sniffing volatile odors from estrous and ovariectomized female mice, suggesting that female mice emit volatile odors which are not excreted into bedding. To test this possibility, we investigated c-Fos expression in the mitral cell layer and granule cell layer of the accessory olfactory bulb 60 min after exposure of male mice to volatile odors without physical contact. Volatile odors from an estrous female mouse significantly increased the total number of c-Fos positive cells in each of the rostral and caudal granule cell layer, but not in the mitral cell layer. After exposure to volatile odors from estrous bedding, the total number of c-Fos positive cells did not increase. Volatile odors from a male mouse did not increase the total number of c-Fos positive cells. Volatile odors from an ovariectomized female mouse increased c-Fos expression only in the caudal granule cell layer. These results suggest that female mice emit specific volatile odors which are not excreted into bedding, and that the volatile odors activate the accessory olfactory system of male mice without physical contact. To characterize the female-specific volatile odors, we conducted habituation-dishabituation tests. Whereas sham-operated male mice discriminated between volatile odors of estrous and ovariectomized female mice, vomeronasal organ-removed male mice did not. These results suggest that male mice discriminated whether or not female mice were ovariectomized, by volatile odors via the accessory olfactory system, and that the female-specific volatile odors are involved in reproduction.

The binding of immobilized IgG2a to Fc gamma 2a receptor activates NF-kappa B via reactive oxygen intermediates and tumor necrosis factor-alpha 1.

The macrophage-like cell line, J774, was found to respond to immobilized mouse monoclonal IgG2a proteins, but not to soluble forms of IgG2a or IgG2b or to immobilized F(ab')2 of IgG2a, by the increase in the nuclear proteins of two different types of NF-kappa B proteins which differed in their electrophoretic mobilities. Fc gamma 2a receptor-mediated activation of NF-kappa B was blocked by the presence of pyrrolidinedithiocarbamate, neutralizing anti-tumor necrosis factor (TNF)-alpha antibodies, various protein kinase inhibitors (H-89, genistein, or heparin) or intracellular calcium chelator (1,2-bis(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra-(acetoxymethyl)-ester, BAPTA/AM) during stimulation. J774 cells were also found to respond to immobilized IgG2a, but not IgG2b, by the increased production of superoxide, H2O2, and TNF-alpha. Fc gamma 2aR-induced production of H2O2 was inhibited by pretreatment of the cells with pyrrolidinedithiocarbamate, H-89, genistein, heparin, or BAPTA/AM, but not with anti-TNF-alpha antibody. Fc gamma 2aR-induced production of TNF-alpha was, on the other hand, not inhibited by pretreatment of the cells with BAPTA/AM. Although J774 cells responded to exogenously added rTNF-alpha, but not to H2O2, by activation of NF-kappa B, the recombinant TNF-alpha-mediated NF-kappa B activation was enhanced by simultaneous presence of H2O2. These results thus suggest that macrophages respond to the stimulation of Fc gamma 2aR by the production of both reactive oxygen intermediates and TNF-alpha and that endogenous TNF-alpha activates NF-kappa B via the pathway involving reactive oxygen intermediates.

Influence of 3' half-site sequence of NF-kappa B motifs on the binding of lipopolysaccharide-activatable macrophage NF-kappa B proteins.

Lipopolysaccharide treatment of mouse macrophage-like J774 cells was found to result in the activation of three different nuclear proteins which specifically bind to oligonucleotide containing the NF-kappa B motif of the human immunodeficiency virus (HIV) gene. These are designated as NF-kappa B1, -kappa B2, and -kappa B3, according to their electrophoretic mobilities (fast, intermediate, and slow, respectively). Immunological and UV cross-linking studies showed that NF-kappa B1 consists of only p50 subunit, whereas both NF-kappa B2 and -kappa B3 contain NF-kappa B p65 subunit and c-Rel. In addition, NF-kappa B2 was also found to contain p50 subunit of NF-kappa B. The binding of three types of NF-kappa B proteins to HIV NF-kappa B motif was effectively inhibited by other NF-kappa B motifs, whose 3' half-site nucleotide sequences are T/A-T-T/C-CC (HIV, interleukin-6, interferon (INF)-beta, H2-Kb, I-E alpha d, and TNF-alpha 2 (nucleotide position -510)) and much less effectively by NF-kappa B motifs with 3' half-site sequences of TGCCC (TNF-alpha 3, nucleotide position -610), ATCTC (G-CSF), TATTC (Fc gamma R), or TCCTT (TNF-alpha 1, nucleotide position -850). Our data also suggested that NF-kappa B1 and -kappa B2 which contain p50 subunit of NF-kappa B bind with the higher preference for NF-kappa B motif of H2-Kb gene promoter than that of INF-beta, whereas NF-kappa B3 which does not contain p50 subunit appears to preferentially bind to NF-kappa B sites of IFN-beta.

Mechanism of lipopolysaccharide-triggered junB activation in a mouse macrophage-like cell line (J774).

The effect of lipopolysaccharide (LPS) on the activation of junB in a mouse macrophage cell line (J774) was investigated. J774 cells responded to either phorbol 12-myristate 13-acetate (PMA) or LPS by the transient increase in the expression levels of c-jun and junB mRNA, but not of junD mRNA. The prior depletion of protein kinase C from J774 cells blocked the action of PMA, but not of LPS, to activate junB. Pretreatment of cells with H-89 or H-7, but not with HA1004, W-7, ML-7, or tyrphostin 47, inhibited LPS-triggered junB activation. Treatment with forskolin also activated junB of J774 cells through an H-89- or H-7-sensitive pathway. Since cAMP-dependent protein kinase activity of J774 cells was inhibited by H-89, but not by H-7, LPS appears to activate junB through a cascade involving two steps, the one sensitive to H-89 and the other to H-7. Western blot analysis showed that LPS-triggered junB activation is accompanied by the increased expression of JunB proteins in the cell lysate as well as in the nuclear extract. JunB in nuclear fraction appears to specifically bind to 12-O-tetradecanoylphorbol-13-acetate-response element (TRE), since preincubation of nuclear extracts with anti-JunB serum reduced the amount of TRE-binding proteins and since the amount of JunB, but not of c-Jun or JunD, immunoprecipitated from TRE-cross-linked nuclear proteins increased in response to LPS. Thus, JunB may play an important role in LPS-triggered gene activation.