There are evidences that exogenous electric currents are capable of enhancing bone formation and resorption, and that the conversion of the bioelectric response to biochemical activity provides the directional component of orthodontic tooth movement. In addition, evidence has implicated cyclic nucleotides in alveolar bone cellular activation mechanism during orthodontic tooth movement. In view of these evidences, this study was performed to investigate the effects of exogenous electric currents in cyclic nuclotide levels in feline alveolar bone and the possible clinical applicaiton of electric currents as an additional orthodontic tool. In the first study, three groups of three adult cats were subjected to application of a constant direct current of 10+/-2 microamperes to gingival tissue near maxillary canine noninvasively for 1,3, and 7 days respectively. In the second study, three groups of three adult cats each were treated by an electric-orthodontic procedure for 1, 3, and 7 days respectively. The left maxillary (control) canine received an orthodontic force of 80gm alone at time of initiation, while the right maxillary (experimental) canine received combined force-electric stimulation (80gm of force and 10+/-2 microamperes of a constant D.C currents). Alveolar bone samples were obtained from the mesial (tension and / or cathode) and the distal (compression and/ or anode) sites surriunding maxillary canines as well as from contralateral control sites. The samples were extracted, boiled, homogenized, and the supernatants were assayed for cyclic nucleotides (cAMP, cGMP) by a radiommunoassay method. And also the amount of tooth movement was measured in the second study. On the basis of this study, the following conclusions can be drawn: 1. The fluctuation pattern of cyclic nucleotide levels in alveolar bone treated by exogenous electric currents was similar to that treated by orthodontic force. 2. The cAMP levels in alveolar bone of electrically treated teeth significantly elevated above the control values. And of electrically treated teeth, the values of the anode sites were higher than those of the cathode sites. 3. The cGMP levels in alveolar bone of electrically teeth elevated above the control values at the initation phase of treatment, but dropped below the control values at time of termination. And of electrically treated teeth, the values of the cathode sites were higher than those of the anode sites. 4. The rate of tooth movement in teeth treated by force-electric combination increased with the length of treatment as compared to that treated by mechanical force alone.
Adult ; Animals ; Cats ; Electrodes ; Humans ; Nucleotides, Cyclic* ; Osteogenesis ; Tooth ; Tooth Movement

To elucidate the mechanism of cyclic nucleotides, such as adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5' -cyclic monophosphate (cGMP), in the regulation of human gastric motility, we examined the effects of forskolin (FSK), isoproterenol (ISO) and sodium nitroprusside (SNP) on the spontaneous, high K+ and acetylcholine (ACh)-induced contractions of corporal circular smooth muscle in human stomach. Gastric circular smooth muscle showed regular spontaneous contraction, and FSK, ISO and SNP inhibited its phasic contraction and basal tone in a concentration-dependent manner. High K+ (50 mM) produced sustained tonic contraction, and ACh (10 micrometer) produced initial transient contraction followed by later sustained tonic contraction with superimposed phasic contractions. FSK, ISO and SNP inhibited high K+-induced tonic contraction and also ACh-induced phasic and tonic contraction in a reversible manner. Nifedipine (1 micrometer), inhibitor of voltage-dependent L-type calcium current (VDCC(L)), almost abolished ACh-induced phasic contractions. These findings suggest that FSK, ISO and SNP, which are known cyclic nucleotide stimulators, inhibit smooth muscle contraction in human stomach partly via inhibition of VDCCL.
Acetylcholine ; Adenosine ; Calcium ; Contracts ; Forskolin ; Guanosine ; Humans ; Isoproterenol ; Muscle, Smooth ; Nifedipine ; Nitroprusside ; Nucleotides, Cyclic ; Relaxation ; Stomach

As a DNA receptor in the cytoplasm,cyclic GMP-AMP synthase (cGAS) can recognize abnormal DNA in the cytoplasm and activate stimulator of interferon genes (STING) to regulate the immune response. The recent studies have demonstrated that this pathway plays a role in non-infectious inflammatory diseases by promoting the expression of type Ⅰ interferon and interferon-stimulated gene.This article reviews the activation and regulation of cGAS-STING pathway in multiple systems and the effect of this pathway on the occurrence and progression of non-infectious inflammatory diseases,providing theoretical reference for future application of cGAS-STING pathway-related drugs in non-infectious inflammatory diseases.
Humans ; Interferons ; Membrane Proteins/metabolism* ; Noncommunicable Diseases ; Nucleotides, Cyclic ; Nucleotidyltransferases/metabolism* ; Signal Transduction

BACKGROUND: Extracellular nucleotides act as agonists to regulate a broad range of physiological processes by interacting with P2 receptors in various tissues including the kidney tubules. This study was undertaken to evaluate the effect of P2 receptor activation on PTH-dependent regulation of phosphate transport in the renal proximal tubular cells. METHODS: Proximal tubular cells were isolated from the rabbit kidney and grown as monolayers on 24 well culture plates. Phosphate uptake was determined by measuring the uptake of radiolabeled phosphate into cell monolayers. Cyclic AMP content was determined by radioimmunoassay using [3H]cAMP assay kit. RESULTS: Activation of P2 receptors with ATP exerted differential effects on phosphate uptake and cAMP generation. In the absence of PTH, it inhibited phosphate uptake and stimulated cAMP generation. In contrast, in the presence of PTH, it attenuated PTH-induced stimulation of cAMP generation and inhibition of phosphate uptake. The profile of the effects of different P2 agonists suggested that P2Y1- and P2Y2-like receptors are involved in the effects of ATP. The effect of ATP to interfere with the PTH-induced regulation was significantly blocked by calphostin C, pertussis toxin or PKC-depletion, whereas, the effects of ATP in the absence of PTH were abolished by indomethacin. CONCLUSION: Our results suggest that PKC-dependent modification of Gi proteins and, subsequently, reduced responsiveness of adenylate cyclases is responsible for the attenuating effect of ATP on the PTH-dependent regulation of phosphate transport in rabbit proximal tubule cells.
Adenosine Triphosphate ; Adenylyl Cyclases ; Cyclic AMP ; Indomethacin ; Kidney ; Kidney Tubules ; Nucleotides ; Parathyroid Hormone ; Pertussis Toxin ; Physiological Processes ; Radioimmunoassay

OBJECTIVEThis work aims to determine the effect of cytosolic bacteria on the expression of cyclic GMP-AMP synthase (cGAS) in human periodontal ligament cells (hPDLCs) and gingival tissues.

METHODSThe ability of Porphyromonas gingivalis (P. gingivalis) to invade hPDLCs was detected using laser scanning confocal microscope assay at a multiplicity of infection of 10. P. gingivalis-infected cells were sorted by fluorescence-activated cell sorting (FACS). Then, quantitative real time reverse transcription polymerase chain reaction (qRT-PCR) and Western blot were used to detect cGAS expression in infected cells. Finally, the location and expression of cGAS in inflammatory and normal gingival tissues were investigated by immunohistochemistry.

RESULTSP. gingivalis actively invaded hPDLCs. Moreover, cGAS expression significantly increased in P. gingivalis-infected cells. Although cGAS was expressed in the epithelial and subepithelial cells of both inflamed and normal gingival tissues, cGAS expression significantly increased in inflamed gingival tissues.

CONCLUSIONSCytosolic bacteria can upregulate cGAS expression in infected cells. These data suggest that cGAS may act as pattern-recognition receptors and participate in recognizing cytosolic nucleic acid pathogen-associated molecular patterns.
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The regulatory role of cyclic nucleotides in the expression of neutrophil responses has been examined. fMLP-stimulated superoxide production in neutrophils was inhibited by dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), histamine, adenosine + theophylline, cAMP elevating agents, and 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) and sodium nitroprusside, cGMP elevating agents. Staurosporine, a protein kinase C inhibitor, genistein, a protein tyrosine kinase inhibitor and chlorpromazine, a calmodulin inhibitor, inhibited superoxide production by fMLP, but they did not further affect the action of DBcAMP on the stimulatory action of fMLP. DBcAMP, histamine, adenosine + theophylline and genistein inhibited myeloperoxidease release evoked by fMLP, whereas BrcGMP, sodium nitroprusside and staurosporine did not affect it. The elevation of (Ca2+)-i evoked by fMLP was inhibited by genistein and chlorpromazine but was not affected by staurosporine. DBcAMP exerted little effect on the initial peak in (Ca2+)-i response to fMLP but effectively inhibited the sustained rise. On the other hand, BrcGMP significantly inhibited both phases. fMLP-induced Mn-2+ influx was inhibited by either DBcAMP or BrcGMP. These results suggest that fMLP-stimulated neutrophil responses may be regulated by cAMP more than cGMP. cAMP and cGMP appear not affect stimulated responses by direct protein kinase C activation. Their regulatory action on the stimulated neutrophil responses may be not influenced by other activation processes.
Adenosine ; Bucladesine ; Calmodulin ; Chlorpromazine ; Genistein ; Hand ; Histamine ; Neutrophils* ; Nitroprusside ; Nucleotides, Cyclic ; Protein Kinase C ; Protein-Tyrosine Kinases ; Staurosporine ; Superoxides ; Theophylline

Members of prostaglandin (PG) E-series elicit cellular effects mainly through adenylyl cyclase-cAMP signaling. The role of PGE2-induced increase in cAMP has been shown to be compartmentalized in the cardiac myocytes: PGE2-induced increase of cAMP is not involved in the control of cardiomyocytic contraction. The purpose of the present study was to define the effect of PGE1 on the cGMP levels and the role of PGE1 in the atrial secretory function. Experiments were performed in perfused beating rabbit atria and atrial contractile responses, cGMP and cAMP efflux, and atrial natriuretic peptide (ANP) secretion were measured. PGE1 increased cGMP as well as cAMP efflux concentration in a concentration-dependent manner, however, no significant changes in atrial secretory responses were observed (with 1.0microM PGE1; for cGMP, 144.76+/-37.5%, n=11 versus -16.81+/-4.76%, n=6, control, p<0.01; for cAMP, 187.60+/-41.52%, n=11 versus 7.38+/-19.44%, n=6, control, p<0.01). PGE1 decreased atrial dynamics slightly but transiently, whereas PGE2 showed similar effects but with lower potency. Isoproterenol increased atrial cAMP efflux (with 2.0 nM; 145.71+/-41.89, n=5 versus 7.38+/-19.44%, n=6, control, p<0.05) and mechanical dynamics and decreased ANP secretion. The PGE1-induced increase in cGMP efflux showed a bell-shaped concentration-response curve. PGE1-induced increase of cGMP efflux was not observed in the presence of L-NAME, an inhibitor of nitric oxide (NO) synthase, or ODQ, an inhibitor of NO-sensitive guanylyl cyclase. L-NAME and ODQ showed no significant effect on the PGE1-induced transient decrease of atrial dynamics. These data indicate that PGE1 increases cGMP levels via NO-soluble GC signaling in the cardiac atrium and also show that PGE1-induced increases in cGMP and cAMP levels are not involved in the regulation of atrial secretory and contractile functions.
Alprostadil* ; Atrial Function ; Atrial Natriuretic Factor ; Dinoprostone ; Guanylate Cyclase ; Isoproterenol ; Myocytes, Cardiac ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nucleotides, Cyclic*

Muscle strips and muscle cells from cat stomach were used to investigate whether spontaneously formed cyclic nucleotides were involved in the inhibition of gastric smooth muscle contraction. A phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), increased the levels of both cyclic GMP (cGMP) and cyclic AMP (cAMP) in resting state cells, while decreasing acetylcholine-induced muscle contraction. Under the influence of IBMX, SQ22536, an adenylyl cyclase inhibitor and methylene blue, a guanylyl cyclase inhibitor completely blocked increases in cAMP and cGMP respectively, without any effect on contraction. However, the combination of SQ22536 and methylene blue completely blocked increases in both cAMP and cGMP levels and stimulated contractions markedly even in the presence of IBMX. Muscle contraction inhibitors such as isoprenaline, vasoactive intestinal polypeptide and sodium nitroprusside also appeared to increase cyclic nucleotide levels which decreased contraction. Which nucleotide increased the most was dependent on the agonist used. Therefore, irrespective of the cyclic nucleotide class, the spontaneous formation of cyclic nucleotides should be considered in evaluating the mechanism of gastric smooth muscle relaxation.
1-Methyl-3-isobutylxanthine ; Adenylyl Cyclases ; Animals ; Cats* ; Cyclic AMP ; Cyclic GMP ; Guanylate Cyclase ; Isoproterenol ; Methylene Blue ; Muscle Cells ; Muscle Contraction ; Muscle Relaxation* ; Muscle, Smooth ; Nitroprusside ; Nucleotides, Cyclic* ; Relaxation ; Stomach ; Vasoactive Intestinal Peptide

The aim of this study was to investigate the effect and action mechanism of quercetin on penile corpus cavernosum smooth muscle (PCCSM). PCCSM precontracted with phenylephrine (Phe) was treated with four different concentrations of quercetin (10−7, 10−6, 10−5 and 10−4 M). PCCSM were preincubated with N-Nitro-L-arginine methyl ester hydrochloride (L-NAME) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) to block nitric oxide synthase and guanylate cyclase, respectively. The changes in PCCSM tension were recorded, and cyclic nucleotides in the perfusate were measured by radioimmunoassay. The interactions of quercetin with phosphodiesterase type 5 inhibitors (PDE5-Is) such as sildenafil, udenafil and mirodenafil, were also evaluated. PCCSM relaxation induced by quercetin occurred in a concentrationdependent manner. The application of quercetin to PCCSM pre-treated with L-NAME and ODQ significantly inhibited the relaxation. Quercetin significantly increased cGMP in the perfusate. Furthermore, quercetin enhanced PDE5-Is-induced relaxation of PCCSM. Quercetin relaxed the PCCSM by activating the NO-cGMP signaling pathway, and it may be a therapeutic candidate or an alternative treatment for patients with erectile dysfunction who do not completely respond to PDE5-Is.
Erectile Dysfunction ; Guanylate Cyclase ; Humans ; Male ; Muscle, Smooth* ; NG-Nitroarginine Methyl Ester ; Nitric Oxide Synthase ; Nucleotides, Cyclic ; Phenylephrine ; Phosphodiesterase 5 Inhibitors ; Quercetin* ; Radioimmunoassay ; Relaxation ; Sildenafil Citrate

In human reproduction, fertilization is the first step for successful pregnancy. From the perspective of sperm physiology, the progressive motility and capacitation, including hyperactivation and acrosome reaction, are the most important factors in the fertilization of oocytes. Numerous studies have demonstrated the roles of calcium ions, cyclic nucleotides, and bicarbonate in the acquisition of progressive motility and capacitation. Among these factors, calcium ion plays the most important role. Sperm possess several calcium channels, including voltage-gated calcium channel, cyclic nucleotide-gated calcium channel, transient receptor potential channel, and channels of the CatSper family The CatSper family is a newly-identified group of four sperm-specific cation channels. CatSper1 and CatSper2 proteins localize on the sperm tail and play a critical role in sperm motility and fertilization. In contrast, CatSper3 and CatSper4 proteinsare expressed only in the acrosomal region of sperm head, which implies that they may have a role in the acrosome reaction. Taken together, the CatSper family is the most important group of calcium channels for regulating sperm physiology and appear to be an attractive target for non-hormonal male contraceptives.
Acrosome Reaction ; Calcium ; Calcium Channels ; Contraceptive Agents, Male ; Fertilization ; Humans ; Ions ; Nucleotides, Cyclic ; Oocytes ; Physiology ; Pregnancy ; Reproduction ; Sperm Head ; Sperm Motility ; Sperm Tail ; Spermatozoa