Octopamine-mediated elevation of cyclic AMP in haemocytes of the American cockroach, Periplaneta americana L.

1987 ◽  
Vol 65 (6) ◽  
pp. 1509-1514 ◽  
Author(s):  
J. W. D. Gole ◽  
G. L. Orr ◽  
R. G. H. Downer
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adult Male ◽  
Periplaneta Americana ◽  
American Cockroach ◽  
Time Dependent ◽  
Blocking Agents ◽  
Adrenergic Blocking ◽  
Camp Levels ◽  
Dose Dependent

The injection of 10 μL of 5 × 10−3 M octopamine into the haemocoel of adult male Periplaneta americana results in a 20 × increase in haemolymph cyclic AMP (cAMP) levels within 3 min. Synephrine also causes a marked increase in haemolymph cAMP, and less pronounced elevations were obtained following the injection of tyramine, dopamine, norepinephrine, 5-hydroxytryptamine, phenylethanolamine, β-phenylethylamine, and L-phenylephrine. The octopamine effect is time dependent for at least 10 min and dose dependent with the EC50 for the injected dose calculated to be about 2.5 × 10−3 M. These results indicate that the octopamine response is receptor mediated and studies on isolated haemocytes suggest that the octopamine-sensitive receptors are located on haemocytes. Incubation of whole haemocytes in medium containing octopamine results in a dose-dependent elevation of cAMP with the EC50 calculated at about 7.5 × 10−6 M. Synephrine, tyramine, and dopamine also elevate cAMP levels in incubated haemocytes, and the activator of adenylate cyclase, forskolin, causes a marked increase in cAMP. The octopamine-mediated response is blocked by mianserin, phentolamine, and cyproheptadine but not by the β-adrenergic blocking agents propranolol and dichloroisoproterenol.

Mode of Action of the Hypertrehalosaemic Peptides from the American Cockroach

1985 ◽  
Vol 40 (9-10) ◽  
pp. 670-676 ◽  
Author(s):  
Gerd Gäde
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Mode Of Action ◽  
Glycogen Phosphorylase ◽  
Fat Body ◽  
American Cockroach ◽  
Dependent Manner ◽  
Low Concentrations ◽  
First Time ◽  
Dose Dependent

Abstract Although crude extracts of cockroach (Periplaneta amencana) corpora cardiaca have been shown previously to affect the activity of adenylate cyclase and phosphorylase, we demonstrate in the present study for the first time that low concentrations (0.5 to 5 pmol) of the synthetic myoactive peptides. M I and M II, also affect these systems; these myoactive peptides are identical to the hypertrehalosaemic hormones I and II, and cause an increase in the concentration of the second messenger cyclic AMP in the fat body.In addition, both octapeptides activate fat body glycogen phosphorylase and promote breakdown of fat body glycogen. Both peptides increase the levels to haemolymph carbohydrate in a dose-dependent manner.

scholarly journals CAP1, an Adenylate Cyclase-Associated Protein Gene, Regulates Bud-Hypha Transitions, Filamentous Growth, and Cyclic AMP Levels and Is Required for Virulence of Candida albicans

2001 ◽  
Vol 183 (10) ◽  
pp. 3211-3223 ◽  
Author(s):  
Yong-Sun Bahn ◽  
Paula Sundstrom
Keyword(s):  
Candida Albicans ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Germ Tube ◽  
Filamentous Growth ◽  
Tube Formation ◽  
Camp Signaling ◽  
Solid Media ◽  
Opportunistic Fungal Pathogen ◽  
Camp Levels

ABSTRACT In response to a wide variety of environmental stimuli, the opportunistic fungal pathogen Candida albicans exits the budding cycle, producing germ tubes and hyphae concomitant with expression of virulence genes, such as that encoding hyphal wall protein 1 (HWP1). Biochemical studies implicate cyclic AMP (cAMP) increases in promoting bud-hypha transitions, but genetic evidence relating genes that control cAMP levels to bud-hypha transitions has not been reported. Adenylate cyclase-associated proteins (CAPs) of nonpathogenic fungi interact with Ras and adenylate cyclase to increase cAMP levels under specific environmental conditions. To initiate studies on the relationship between cAMP signaling and bud-hypha transitions in C. albicans, we identified, cloned, characterized, and disrupted the C. albicans CAP1 gene. C. albicans strains with inactivated CAP1 budded in conditions that led to germ tube formation in isogenic strains withCAP1. The addition of 10 mM cAMP and dibutyryl cAMP promoted bud-hypha transitions and filamentous growth in thecap1/cap1 mutant in liquid and solid media, respectively, showing clearly that cAMP promotes hypha formation in C. albicans. Increases in cytoplasmic cAMP preceding germ tube emergence in strains having CAP1 were markedly diminished in the budding cap1/cap1 mutant. C. albicans strains with deletions of both alleles ofCAP1 were avirulent in a mouse model of systemic candidiasis. The avirulence of a germ tube-deficientcap1/cap1 mutant coupled with the role of Cap1 in regulating cAMP levels shows that the Cap1-mediated cAMP signaling pathway is required for bud-hypha transitions, filamentous growth, and the pathogenesis of candidiasis.

Effect of histamine on canine gastric mucosal adenylate cyclase.

1977 ◽  
Vol 232 (1) ◽  
pp. E35
Author(s):  
R R Dozois ◽  
A Wollin ◽  
R D Rettmann ◽  
T P Dousa
Keyword(s):  
Gastric Mucosa ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Antral Mucosa ◽  
Fundic Mucosa ◽  
H2 Receptors ◽  
Dose Dependent ◽  
Stimulation Of

The effects of histamine, Nalpha-dimethylhistamine, 4,5-methylhistamine, Ntau-methylhistamine, pentagastrin, carbachol, and NaF on the adenylate cyclase activity from canine gastric mucosa were investigated in cell-free preparations. In gastric fundic mucosa, histamine (10(-4) M), Nalpha-dimethylhistamine (10(-4) M), 4,5-methylhistamine (10(-4 M), and NaF (10)-2) M) significantly (P less than 0.001) increased adenylate cyclase activity (means+/-SE) by 44.7+/-6.6, 49.4+/-6.7, 34.0+/-6.4, and 572.0+/-100%, respectively, above basal activity. The effect of histamine and Na-dimethyl histamine was dose-dependent. In contrast, other tested agents failed to stimulate the formation of cyclic AMP in gastric fundic mucosa. Metiamide (10(-4) M) blocked the stimulation of fundic mucosa adenylate cyclase by histamine and Nalpha-dimethylhistamine, without significantly altering basal and NaF-induced adenylate cyclase activity. Histamine, however, did not stimulate the adenylate cyclase activity from the gastric antral mucosa. The findings support the proposal that the canine gastric acid response to histamine may be mediated by cyclic AMP formed in response to stimulation of histamine H2-receptors.

scholarly journals Cyclic AMP Signaling Pathway Modulates Susceptibility of Candida Species and Saccharomyces cerevisiae to Antifungal Azoles and Other Sterol Biosynthesis Inhibitors

2003 ◽  
Vol 47 (10) ◽  
pp. 3195-3201 ◽  
Author(s):  
Pooja Jain ◽  
Indira Akula ◽  
Thomas Edlind
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Signaling Pathway ◽  
Sterol Biosynthesis ◽  
Fungistatic Activity ◽  
Species Analysis ◽  
Resistant Strains ◽  
Camp Levels ◽  
Selection Of

ABSTRACT Azoles are widely used antifungals; however, their efficacy is compromised by fungistatic activity and selection of resistant strains during treatment. Recent studies demonstrated roles for the protein kinase C and calcium signaling pathways in modulating azole activity. Here we explored a role for the signaling pathway mediated by cyclic AMP (cAMP), which is synthesized by the regulated action of adenylate cyclase (encoded by CDC35 in Candida albicans and CYR1 in Saccharomyces cerevisiae) and cyclase-associated protein (encoded by CAP1 and SRV2, respectively). Relative to wild-type strains, C. albicans and S. cerevisiae strains mutated in these genes were hypersusceptible to fluconazole (>4- to >16-fold-decreased 48-h MIC), itraconazole (>8- to >64-fold), or miconazole (16- to >64-fold). Similarly, they were hypersusceptible to terbinafine and fenpropimorph (2- to >16-fold), which, like azoles, inhibit sterol biosynthesis. Addition of cAMP to the medium at least partially reversed the hypersusceptibility of Ca-cdc35 and Sc-cyr1-2 mutants. An inhibitor of mammalian adenylate cyclase, MDL-12330A, was tested in combination with azoles; a synergistic effect was observed against azole-susceptible and -resistant strains of C. albicans and five of six non-C. albicans Candida species. Analysis of cAMP levels after glucose induction in the presence and absence of MDL-12330A confirmed that it acts by inhibiting cAMP synthesis in yeast. RNA analysis suggested that a defect in azole-dependent upregulation of the multidrug transporter gene CDR1 contributes to the hypersusceptibility of the Ca-cdc35 mutant. Our results implicate cAMP signaling in the yeast azole response; compounds similar to MDL-12330A may be useful adjuvants in azole therapy.

Haemolymph octopamine levels during and following flight in the American cockroach, Periplaneta americana L.

1984 ◽  
Vol 62 (1) ◽  
pp. 19-22 ◽  
Author(s):  
B. A. Bailey ◽  
R. J. Martin ◽  
R. G. H. Downer
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
Adult Male ◽  
High Performance ◽  
Periplaneta Americana ◽  
American Cockroach

Haemolymph octopamine levels of adult male cockroaches (Periplaneta americana) were monitored using high performance liquid chromatography with electrochemical detection. The octopamine concentration of haemolymph increases rapidly in response to experimental handling and the commencement of flight, with 77 and 123% elevations, respectively, observed within 1 min of initiating these activities. Resting levels are rapidly restored when flight ceases. The results support the suggestion that octopamine mediates a generalized sympathetic-like response to excitation.

scholarly journals Changes in adenosine receptors during differentiation of 3T3-F442A cells to adipocytes

1988 ◽  
Vol 249 (2) ◽  
pp. 377-381 ◽  
Author(s):  
K Ravid ◽  
J M Lowenstein
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adenosine Receptors ◽  
Positive Response ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Similar Extent ◽  
Phenylisopropyl Adenosine ◽  
Dose Dependent ◽  
Basal Concentration

Incubation of undifferentiated 3T3-F442A cells (preadipocytes) with 5′-N-ethylcarboxamidoadenosine (NECA) increases intracellular cyclic AMP in a dose-dependent manner. The effect of NECA is antagonized by 8-phenyltheophylline, but potentiated by 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidine, an inhibitor of cyclic AMP phosphodiesterase. Incubation of preadipocytes with (-)-N6-(R-phenylisopropyl)adenosine (PIA) has no inhibitory effect on the basal concentration of cyclic AMP or on the stimulation of adenylate cyclase by isoprenaline or forskolin. Micromolar concentrations of PIA increase intracellular cyclic AMP, but with a lower potency than NECA. Similar findings are obtained with the non-differentiating cell line 3T3-C2. Thus preadipocyte 3T3-F442A cells and 3T3-C2 cells appear to express only stimulatory adenosine receptors. For some time after 3T3-F442A cells have differentiated to adipocytes, micromolar concentrations of NECA and PIA continue to increase cyclic AMP to a similar extent to that in preadipocytes, whereas nanomolar concentrations of PIA decrease the stimulatory effects of isoprenaline and forskolin on adenylate cyclase by 50%. However, several days after differentiation, the adipocytes gradually lose the major part of their positive response to NECA and reach a steady response to NECA 10 days after differentiation. The inhibition of adenylate cyclase caused by PIA remains constant for at least 2 weeks after differentiation. With membranes derived from the cells, the effects of NECA and PIA depend on GTP. These results indicate that, during the differentiation of 3T3-F442A cells to adipocytes, new inhibitory adenosine receptors are expressed, whereas the stimulatory receptors become attenuated.

scholarly journals Enhancement of Platelet Activity by Inhibition of Adenylate Cyclase

1977 ◽  
Author(s):  
E. W. Salzman ◽  
D. E. Macintyre ◽  
J. L. Gordon ◽  
M. Steer
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Narrow Range ◽  
Calcium Ionophore ◽  
Serotonin Release ◽  
Platelet Response ◽  
Platelet Activity ◽  
Camp Levels

Induction of the platelet response to ADP and many other agonists is accompanied by reduction from basal level of cyclic AMP (cAMP) . The Squibb compound 22536 (9-(tetrahydro-2-furyl)-adenine), an inhibitor of lung adenylate cyclase (Harris et al. Fed. Proc. 34:617, 1975), reverses the inhibition of platelet function and prevents elevation of platelet cAMP by drugs that stimulate adenylate cyclase, including PGE1, PGD2 and adenosine. It reduces basal and PGE1-or NaF-stimulated adenylate cyclase activity and enhances the inhibition of basal activity induced by epinephrine. SQ22536 reduces basal cAMP levels but does not initiate the release reaction or platelet aggregation. It does, however, increase the effect on cAMP of platelet stimulants such as ADP and epinephrine and enhances serotonin release and aggregation induced by ADP, epinephrine, collagen, thrombin, arachidonic acid, endoperoxide PGG2, centrifugation, and rewarming after chilling. Enhancement of platelet activity by SQ22536 in citrated PRP is demonstrable only over a narrow range of agonist concentrations where primary aggregation without release is transformed to complete aggregation with release. SQ22536 does not enhance platelet stimulation by vasopressin, serotonin, or the calcium ionophore Lilly A23187; these substances activate platelets without lowering cyclic AMP, unlike the stimuli listed above. In heparinized PRP, ADP-induced platelet aggregation is accompanied by serotonin release in the presence (but not in the absence) of SQ22536. These results suggest that reduction of cAMP may be involved in the initiation of release in platelets conditioned by a variety of phenomena, including primary aggregation.

scholarly journals ADP-induced platelet shape change and mobilization of cytoplasmic ionized calcium are mediated by distinct binding sites on platelets: 5'- p-fluorosulfonylbenzoyladenosine is a weak platelet agonist

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 751-756 ◽  
Author(s):  
AK Rao ◽  
MA Kowalska
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Binding Sites ◽  
Calcium Concentration ◽  
Shape Change ◽  
Ionized Calcium ◽  
Platelet Binding ◽  
Thiol Reagent ◽  
Dose Dependent ◽  
Platelet Shape

Abstract Platelet stimulation with ADP results in several responses, including shape change, increase in cytoplasmic ionized calcium concentration [Ca2+]i, an inhibition of adenylate cyclase. 5′-p-Fluorosulphonyl benzoyladenosine (FSBA), which covalently labels an ADP binding site on platelets, blocks platelet shape change but not the inhibition of cyclic AMP levels by ADP, whereas p-chloromercuribenzenesulfonate (pCMBS), a nonpenetrating thiol reagent, has the opposite effects. We examined the effect of FSBA and pCMBS on ADP-induced increase in [Ca2+]i using platelets loaded with fluorescent Ca2+ indicators quin2 and fura-2. FSBA (50 to 200 mumol/L) induced a dose-dependent rise in [Ca2+]i, indicating that it is a weak platelet agonist. Under conditions of covalent labeling of the ADP binding sites, FSBA (50 to 100 mumol/L) did not inhibit the ADP-induced increase in [Ca2+]i or its inhibition of adenylate cyclase, whereas pCMBS (up to 1 mmol/L) abolished both these responses but not shape change. These findings suggest that ADP-induced Ca2+ mobilization and inhibition of adenylate cyclase are mediated by platelet binding sites distinct from those mediating shape change.

Sign in / Sign up

Export Citation Format

Share Document