Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Porcine vasoactive intestinal peptide stimulated adenosine 3':5'-monophosphate (cyclic AMP) production in rat intestinal epithelial cells. The stimulation was dependent on time and temperature and was potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Under optimal conditions (at 15 degrees C, with 0.2 mM 3-isobutyl-1-methylaxanthine, at a cell concentration up to 18 microgram DNA/ml), the cyclic AMP production produced by vasoactive intestinal peptide was constant for 10 min and stopped after 15 min incubation, at either low (1 nM) or high (30 nM) concentration of the peptide. This plateau effect was demonstrated not to be due to an inactivation of vasoactive intestinal peptide in the medium nor to an alteration of receptors for the peptide. Cyclic AMP production was sensitive to a concentration as low as 0.1 nM vasoactive intestinal peptide. Maximal stimulation of cyclic AMP levels by vasoactive intestinal peptide was observed with 30 nM vasoactive intestinal peptide and represented an 11-fold increased above basal. The dorse-response curve was monophasic with a Km of 2.3 x 10(-9) M. No cooperative effects were detected by Hill analysis. The positive non-linear relationship observed between stimulation of cyclic AMP production and occupancy of binding site was not time-dependent as indicated by experiments performed after 15, 45 and 120 min incubation. Maximal and half-maximal responses were obtained at about 70% and 7% occupation of binding sites, respectively. Chicken vasoactive intestinal peptide and porcine secretin were agonists of porcine vasoactive intestinal peptide with a 6-times and a 120-times lower potency, respectively. Among secretin analogs that were found to have low affinity for vasoactive intestinal peptide binding sites, [4-alanine, 5-valine]secretin, that resembles vasoactive intestinal peptide at the first seven amino acids at the N-terminal end, was a partial agonist of vasoactive peptide at the first seven amino acids at the N-terminal end, was a partial agonist of vasoactive intestinal peptide and others failed to stimulate cyclic AMP production. Glucagon (10microM), gastric inhibitory peptide (0.1 microM), substance, P, neurotensin, octapeptide of cholecystokinin, bovine pancreatic polypeptide, human gastrin I with leucine at residue 15, Leu-enkephalinand somatostatin (1 microM) did not alter cyclicAMP levels. Non-peptide mediators such as dopamine, serotonin, acetylcholine and histamine, tested at 10 microM, were also ineffective. Prostaglandins E2, E1 and isoproterenol, tested at 10 microM, induced an increase of cyclic AMP levels above basal but were 9.5, 13.7 and 17.5 times less efficient than vasoactive intestinal peptide, respectively. Thus vasoactive intestinal peptide is a unique stimulus of cyclic AMP production in rat intestinal epithelial cells.
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PMID:Interaction of vasoactive intestinal peptide with isolated intestinal epithelial cells from rat. 2. Characterization and structural requirements of the stimulatory effect of vasoactive intestinal peptide on production of adenosine 3':5'-monophosphate. 8 68

CCK-secreting WE rat medullary thyroid carcinoma cell line resembles other calcitonin-producing (C-cell) lines in that calcium, cAMP, or agents which raise cAMP, dexamethasone, and beta-adrenergic agents all stimulate peptide secretion. Unlike other C-cell lines, the WE cells respond similarly to IBMX (3-isobutyl-1-methyl-xanthine, a phosphodiesterase inhibitor) in the presence and absence of forskolin, implying that these cells secrete substances that raise cAMP levels, whose effect is accentuated by IBMX. Both CGRP and neurotensin, peptides that may be secreted by these cells, caused a small, but significant, increase in CCK secretion. It is possible that these or other secreted substances that activate adenylate cyclase are responsible for the cell's high rate of CCK secretion. Their high rate of CCK synthesis and their regulated secretion suggest that these cells will be a good model for studies of CCK expression, biosynthesis, and processing.
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PMID:Regulation of cholecystokinin secretion from a rat medullary thyroid carcinoma cell line: role of calcium, cyclic nucleotides, glucocorticoids, neurotensin, and calcitonin gene-related peptide. 152 66

Using a recently developed canine primary enteric endocrine cell culture system, we have investigated the role of adenosine 3',5'-cyclic monophosphate (cAMP) in mediating the release of neurotensin and enteroglucagon. Epinephrine-stimulated peptide release was concomitant with an increase in cAMP accumulation. Carbachol and somatostatin (SRIF) markedly inhibited the epinephrine effect on both peptide release and cAMP content. The addition of 3-isobutyl-1-methylxanthine potentiated epinephrine-stimulated peptide release without altering the relative inhibition by carbachol and SRIF, suggesting that these agents did not inhibit endocrine cell function by increasing phosphodiesterase activity. To determine the role of cAMP production in mediating inhibition of peptide release, cells were incubated with the bacterial toxin, pertussis toxin (PT). In cultures pretreated with PT, carbachol inhibition of both peptide release and cAMP accumulation was completely reversed. In contrast, SRIF inhibition of cAMP content was completely reversed after PT treatment, but inhibition of peptide release was only partially reversed. Additionally, toxin treatment only partially reversed SRIF inhibition of forskolin- and calcium ionophore-stimulated peptide release. These data suggest that muscarinic cholinergic inhibition of neurotensin and enteroglucagon release is mediated entirely through the guanine nucleotide-binding protein (Ni) or a similar toxin-sensitive, GTP-binding protein. SRIF-inhibited peptide release is mediated partially through a toxin-sensitive substrate, as evidenced by PT reversal of reduced cAMP levels. SRIF may also inhibit neurotensin and enteroglucagon release by a cAMP-independent pathway that is not coupled to Ni or a similar PT-sensitive, GTP-binding protein.
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PMID:Somatostatin and muscarinic inhibition of canine enteric endocrine cells: cellular mechanisms. 244 8

Characterization of specific vasopressin binding sites was investigated in purified mouse Leydig cells using tritiated arginine-vasopressin. Binding of radioligand was saturable, time- and temperature-dependent and reversible. (3H)-AVP was found to bind to a single class of sites with high affinity (Kd = 2.20 +/- 0.18 nM) and low capacity (Bmax = 17.4 +/- 1.8 fmol/10(6) Leydig cells). Binding displacements with specific selective analogs of AVP indicated the presence of V1 subtype receptors on Leydig cells. The ability of AVP to displace (3H)-AVP binding was greater than LVP and oxytocin. The unrelated peptides, somatostatin and substance P, were less potent, while neurotensin and LHRH did not displace (3H)-AVP binding. The time-course effects of AVP-pretreatment on basal and hCG-stimulated testosterone and cAMP accumulations were studied in primary culture of Leydig cells. Basal testosterone accumulation was significantly increased by a 24 h AVP-pretreatment of Leydig cells (P less than 0.001). This effect was potentiated by the phosphodiesterase inhibitor (MIX) and was concomitantly accompanied by a slight but significant increase in cAMP accumulation (P less than 0.01). AVP-pretreatment of the cells for 72 h had no effect on basal testosterone accumulation, but exerted a marked inhibitory effect on the hCG-stimulated testosterone accumulation (P less than 0.001). This reduction of testosterone accumulation occurred even in the presence of MIX and was not accompanied by any significant change of cAMP levels. We conclude from these data that AVP is capable of modulating steroidogenesis in Leydig cells through specific and functionally V1 receptor subtype and postulate that this effect may be part of an intratesticular paracrine/autocrine control mechanism.
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PMID:Modulation of mouse Leydig cell steroidogenesis through a specific arginine-vasopressin receptor. 245 54

Functional and specific receptors for vasoactive intestinal peptide (VIP) (determined by their capacity to bind 125I-VIP and activate adenylate cyclase) and cyclic AMP-dependent phosphodiesterase activities were characterized in enterocytes of human fetal small intestine between 18 and 23 weeks of gestation. Half-maximal stimulation of the cyclase and inhibition of 125I-VIP binding in membrane preparations were respectively observed at 1.4 and 5 X 10(-10) M VIP. The peptides structurally related to VIP activated the cyclic AMP generating system at pharmacological doses (10(-7) M and above) in the following order of potency: VIP greater than PHI greater than GRF greater than secretin. Other peptides or test substances, including GIP, pancreatic glucagon, somatostatin-14, gastrin, CCK, neurotensin, pancreatic polypeptide, PYY, substance P, histamine and isoproterenol are inactive in this system, while the ubiquitous adenylate cyclase activators NaF, forskolin and prostaglandins were effective. These results, combined with the appearance of intestinal VIP in nerve fibers at 8 weeks and with the morphological and enzymatic maturation at 9-12 weeks of the intestinal mucosa, indicate that this neuropeptide may regulate either the differentiation or function of enterocytes during the early development of human intestinal mucosa.
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PMID:Vasoactive intestinal peptide receptor activity in human fetal enterocytes. 298 18

The effect of lithium ion (Li+) on receptor-mediated synthesis of cyclic GMP, a putative second messenger, was examined using intact murine neuroblastoma cells (clone N1E-115). Lithium chloride potently inhibited cyclic GMP formation stimulated by the neuropeptides, neurotensin, angiotensin II and bradykinin in an identical concentration-dependent (IC50 s of around 12 mM), saturable and reversible manner. In the presence of veratridine, an alkaloid which by stimulating sodium channels can increase Li+ entry into the cells, Li+ inhibited neurotensin-stimulated cyclic GMP formation more potently (IC50 = 7 mM). No effect of Li+ was observed on phosphodiesterase (EC 3.1.4.17) activity. These results suggest that Li+ may interfere with the function of these receptors through its inhibitory effect at a common site in the pathway of receptor-mediated cyclic GMP formation.
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PMID:Lithium ions have a potent and selective inhibitory effect on cyclic GMP formation stimulated by neurotensin, angiotensin II and bradykinin. 301 10

We have assessed the influence of forskolin, a potent activator of adenylate cyclase, on histamine release by neurotensin (NT) in the rat perfused hind limb. The results indicate that forskolin, in concentrations known to increase the cyclic AMP content of various tissues, markedly inhibits the histamine releasing effect of NT. The inhibitory action of forskolin was mimicked by a synthetic cyclic AMP derivative and by 3-isobutyl-1-methyl-xanthine (IBMX), a potent phosphodiesterase inhibitor. Our results suggest that the inhibitory action of forskolin toward histamine release by NT in the rat hind limb mast cells results from the activation of a cyclic AMP-generating system in mast cells.
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PMID:Forskolin inhibits histamine release by neurotensin in the rat perfused hind limb. 620 75

Vasoactive intestinal peptide (VIP) has been shown to increase cyclic AMP content in isolated epithelial cells of rat ventral prostate. The stimulatory effect of VIP was dependent on time and temperature and was potentiated by a phosphodiesterase inhibitor. At 15 degrees C, the response occurred in the 1 X 10(-10)-10(-7)M range of VIP concentrations. Half-maximal stimulation of cellular cyclic AMP was obtained at 1.4 nM and maximal stimulation (3-fold basal level) at about 100 nM VIP. Chicken VIP and porcine secretin were agonists of porcine VIP but exhibited a 2-times higher and a 170-times lower potency, respectively. A high concentration (1 X 10(-6)M) of glucagon, somatostatin, neurotensin, substance P, Met-enkephalin or Leu-enkephalin did not modify cAMP levels. The finding of a VIP-stimulated cAMP system in rat prostatic epithelial cells together with the previous characterization of high-affinity receptors for VIP in the same cell preparation, as well as the presence of VIP-containing neurones innervating the male genitourinary tract, strongly suggest that VIP may be involved in prostatic growth regulation and function.
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PMID:Cyclic AMP-stimulating effect of vasoactive intestinal peptide in isolated epithelial cells of rat ventral prostate. 631 52

1. A widespread mechanism of slow excitation throughout the nervous system involves overlapping changes in nonselective ion conductance and K+ conductance. We used whole cell patch-clamp recording to characterize such a nonselective conductance induced by neurotensin (NT) and other neurotransmitters in immunocytochemically identified dopaminergic neurons cultured from the rat ventral tegmental area (VTA). 2. The NT-induced inward current consisted of an initial peak and later "hump." The response was blocked reversibly by the nonpeptide NT-receptor antagonist SR48692, suggesting that it resulted from activation of NT receptors. 3. The channel was almost equally permeable to Na+ and K+, as determined from the reversal potential shift upon switching from Na+- to K(+)-containing external solution. The permeability of Cs+ was similar to that of Na+, as determined from the zero-current equation and average reversal potential in the 75 mM Na+ solution. Cl- was not significantly permeable. 4. In Ca(2+)-free external solution, the NT-induced current showed a fourfold increase in amplitude, and in high Mg2+ (20 mM) external solution, the NT-induced current showed an 80% decrease in amplitude, suggesting that external Ca2+ and Mg2+ could block the nonselective conductance. 5. The NT response was unaffected by loading the neurons with either the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or with 1 mM ca2+. The nonselective conductance was therefore not Ca2+ activated. 6. Loading the neurons with cyclic GMP or cyclic AMP (each with the phosphodiesterase inhibitor isobutyl-methylxanthine) did not affect the NT response. The NT-induced nonselective conductance was therefore not cyclic nucleotide-activated. 7. The latency of the NT response was long (> or = 185 ms, average 406 ms, 30 degrees C), indicating that NT did not induce the conductance through ligand-gated channels. Thus, NT activated a slow nonselective cation conductance. 8. Neurokinin B, a metabotropic glutamate agonist, and muscarine elicited responses similar to the NT response. The NT response could be elicited after desensitizing the responses to these other neurotransmitters, indicating receptor specificity in the activation of the nonselective conductance.
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PMID:Properties of a slow nonselective cation conductance modulated by neurotensin and other neurotransmitters in midbrain dopaminergic neurons. 889 Mar 7

Leptin signaling in the hypothalamus is required for normal food intake and body weight homeostasis. Recent evidence suggests that besides the signal transducer and activator of transcription-3 (STAT3) pathway, several non-STAT3 pathways mediate leptin signaling in the hypothalamus. We have previously demonstrated that leptin stimulates phosphodiesterase-3B (PDE3B) activity in the hypothalamus, and PDE3 inhibitor cilostamide reverses anorectic and body weight reducing effects of leptin. To establish the physiological role of PDE3B signaling in the hypothalamus, we examined if leptin signaling through the PDE3B pathway is responsible for the activation of proopiomelanocortin (POMC) and neurotensin (NT) neurons, which are known to play a critical role in energy homeostasis. To this end, we assessed the effect of cilostamide on leptin-induced POMC and NT gene expression in the rat hypothalamus. Results showed that while central injection of leptin significantly increased both POMC and NT mRNA levels in the medial basal hypothalamus, cilostamide completely reversed this effect of leptin suggesting a PDE3B-activation dependent induction of POMC and NT gene expression by leptin. This result further suggests that the PDE3B pathway plays an important role in mediating leptin action in the hypothalamus.
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PMID:A role of phosphodiesterase-3B pathway in mediating leptin action on proopiomelanocortin and neurotensin neurons in the hypothalamus. 2047 54


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