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The effects of thyroxine treatment on slow- and fast-contracting skeletal muscle contractions of the cat and their cyclic AMP level

Merican Z, Sukumaran S, Raji VL, Rajikin MH, Khalid BA

Clin Exp Pharmacol Physiol, 1992 Dec;19(12):843-6.
PMID: 1335382

1. The effects of thyroxine treatment on soleus and extensor digitorum longus (EDL) muscle contractions and their cyclic adenosine 3',5'-monophosphate (cyclic AMP) levels were examined in anaesthetized cats. 2. Thyroxine treatment decreased the tension of incomplete tetanic contractions of the soleus as well as the EDL muscles. The effect on tension of these muscles was not associated with an increase in the cyclic AMP level of the muscle as is the case with a beta 2-adrenoceptor agonist effect. 3. The results do not support the involvement of cyclic AMP in the tension depressant effect of thyroxine on contractions of skeletal muscle. 4. It is suggested that the muscle weakness and tremor observed in thyrotoxicosis and during administration of beta 2-adrenoceptor agonists are mediated by different mechanisms.

Matched MeSH terms: Cyclic AMP/metabolism*
Testosterone decreases fluid and chloride secretions in the uterus of adult female rats via down-regulating cystic fibrosis transmembrane regulator (CFTR) expression and functional activity

Mohd Mokhtar H, Giribabu N, Kassim N, Muniandy S, Salleh N

J Steroid Biochem Mol Biol, 2014 Oct;144 Pt B:361-72.
PMID: 25125390 DOI: 10.1016/j.jsbmb.2014.08.007

Estrogen is known to stimulate uterine fluid and Cl(-) secretion via CFTR. This study investigated testosterone effect on these changes in a rat model.

Matched MeSH terms: Cyclic AMP/metabolism
Effects of steroid hormones pretreatment on isoprenaline-induced cyclic adenosine 3',5'-monophosphate in rat lung

Nabishah BM, Merican Z, Morat PB, Alias AK, Khalid BA

Gen. Pharmacol., 1990;21(6):935-8.
PMID: 2177714

1. Steroid hormones have been shown to regulate the concentration of adrenergic and muscarinic receptors in many tissues. 2. The cyclic adenosine 3',5'-monophosphate (cAMP) content in rat lung tissues in response to either dexamethasone, corticosterone, deoxycorticosterone or progesterone for 7 days were measured following intraperitoneal injection of isoprenaline just before sacrificed. 3. There was a significant increase in cAMP level (P less than 0.001) in dexamethasone and corticosterone-treated rats compared to controls that received isoprenaline alone. 4. Pretreatment with deoxycorticosterone and progesterone suppressed the increase in cAMP in response to isoprenaline. 5. The effect of glucocorticoids in causing bronchodilatation in asthmatic patients is partly due to the restoration of adenyl cyclase responsiveness to beta-agonist.

Matched MeSH terms: Cyclic AMP/metabolism*
Effects of steroid hormones on cyclic adenosine 3',5'-monophosphate levels in the rat lung

Nabishah BM, Khalid BA, Morat PB, Alias AK, Zainuddin M

J Endocrinol, 1992 Jul;134(1):73-6.
PMID: 1323640

The possible role of cyclic adenosine 3',5'-monophosphate (cAMP) in mediating the action of steroid hormones was investigated using the rat lung. Male rats were adrenalectomized and treated with olive oil, dexamethasone, corticosterone, deoxycorticosterone (DOC) or progesterone. At the end of 10 days, 100 micrograms isoprenaline/kg was injected intraperitoneally 5 min before the animals were killed to stimulate cAMP production. Adrenalectomy significantly decreased cAMP levels in the rat lung. Dexamethasone and corticosterone pretreatment reversed the effect of adrenalectomy whereas progesterone pretreatment but not DOC pretreatment significantly decreased lung cAMP levels. Cyclic AMP levels in normal female rats, whether pregnant or not, were not significantly different from those in male rats. We concluded that the absence of glucocorticoid, as after adrenalectomy, decreased the cAMP levels in rat lungs and that this could be reversed by either dexamethasone or corticosterone replacement. Progesterone reduced the cAMP content in rat lungs by acting as a glucocorticoid antagonist or by acting directly via progesterone receptors.

Matched MeSH terms: Cyclic AMP/metabolism*
The effect of mitragynine on cAMP formation and mRNA expression of mu-opioid receptors mediated by chronic morphine treatment in SK-N-SH neuroblastoma cell

Jamil MF, Subki MF, Lan TM, Majid MI, Adenan MI

J Ethnopharmacol, 2013 Jun 21;148(1):135-43.
PMID: 23608241 DOI: 10.1016/j.jep.2013.03.078

ETHNOPHARMACOLOGICAL RELEVANCE: [corrected] Mitragynine is an indole alkaloid compound of Mitragyna speciosa (M. speciosa) Korth. (Rubiaceae). This plant is native to the southern regions of Thailand and northern regions of Malaysia and is frequently used to manage the withdrawal symptoms in both countries.
AIM OF STUDY: To investigate the effect of mitragynine after chronic morphine treatment on cyclic AMP (cAMP) level and mRNA expression of mu-opioid receptor (MOR) in human neuroblastoma SK-N-SH cell.
METHOD AND MATERIALS: Mitragynine was isolated from the Mitragyna speciosa plant using the acid-base extraction method. The cAMP level upon forskolin stimulation in the cells was determined using the Calbiochem(®) Direct Immunoassay Kit. The mRNA expression of the MOR was carried out using quantitative RT-PCR.
RESULT: Cotreatment and pretreatment of morphine and mitragynine significantly reduced the production of cAMP level at a lower concentration of mitragynine while the higher concentration of this compound could lead to the development of tolerance and dependence as shown by the increase of the cAMP level production in foskolin stimulation. In MOR mRNA expression study, cotreatment of morphine with mitragynine significantly reduced the down-regulation of MOR mRNA expression as compared to morphine treatment only.
CONCLUSION: These finding suggest that mitragynine could possibly avoid the tolerance and dependence on chronic morphine treatment by reducing the up-regulation of cAMP level as well as reducing the down-regulation of MOR at a lower concentration of mitragynine.

Matched MeSH terms: Cyclic AMP/metabolism*
Estrogen and progesterone differentially regulate the levels of cystic fibrosis transmembrane regulator (CFTR), adenylate cyclase (AC), and cyclic adenosine mono-phosphate (cAMP) in the rat cervix

Ismail N, Giribabu N, Muniandy S, Salleh N

Mol. Reprod. Dev., 2015 Jun;82(6):463-74.
PMID: 26018621 DOI: 10.1002/mrd.22496

The consistency of the cervical mucus changes with the reproductive cycle, which we hypothesized involved changing levels of cystic fibrosis transmembrane regulator (CFTR), adenylate cyclase (AC), and cyclic adenosine mono-phosphate (cAMP). We therefore measured the abundance of each in the rat cervix under estrogen and progesterone influence to determine if the activity of these components could explain the changes in the consistency of cervical mucus. Ovariectomised adult female rats were treated with three days of either estrogen (1 μg/kg/day) or progesterone (20 mg/kg/day), or three days of estrogen followed by two days of either vehicle or progesterone or estrogen plus progesterone. In some groups, mifepristone (7 mg/kg/day) was concurrently given with progesterone. Animals were then sacrificed, and the cervix was harvested for protein and mRNA expression analyses by Western blot and real-time PCR, respectively. The distribution of proteins was investigated by immunohistochemistry, and levels of cAMP were determined by enzyme-linked immunosorbent assay (ELISA). Cftr mRNA, AC protein, and cAMP levels in cervical homogenates as well as the tissue distribution of CFTR and AC in endocervical epithelia were highest under estrogen influence; the opposite pattern was seen under progesterone influence. Cervical lumen circumference was highest under estrogen and lowest under progesterone. The effects of progesterone were antagonized by mifepristone. Therefore, increased abundance of CFTR, AC, and cAMP under estrogen influence could account for the increased fluid accumulation within the cervical lumen, which would contribute to lower cervical mucus consistency, whereas progesterone reverses this effect at the molecular and organ level.

Matched MeSH terms: Cyclic AMP/metabolism*
Fulltext Malaysian Tualang Honey Inhibits Hydrogen Peroxide-Induced Endothelial Hyperpermeability

Devasvaran K, Tan JJ, Ng CT, Fong LY, Yong YK

Oxid Med Cell Longev, 2019;2019:1202676.
PMID: 31531177 DOI: 10.1155/2019/1202676

Malaysian Tualang honey (TH) is a known therapeutic honey extracted from the honeycombs of the Tualang tree (Koompassia excelsa) and has been reported for its antioxidant, anti-inflammatory, antiproliferative, and wound healing properties. However, the possible vascular protective effect of TH against oxidative stress remains unclear. In this study, the effects of TH on hydrogen peroxide- (H2O2-) elicited vascular hyperpermeability in human umbilical vein endothelial cells (HUVECs) and Balb/c mice were evaluated. Our data showed that TH concentrations ranging from 0.01% to 1.00% showed no cytotoxic effect to HUVECs. Induction with 0.5 mM H2O2 was found to increase HUVEC permeability, but the effect was significantly reversed attenuated by TH (p < 0.05), of which the permeability with the highest inhibition peaked at 0.1%. In Balb/c mice, TH (0.5 g/kg-1.5 g/kg) significantly (p < 0.05) reduced H2O2 (0.3%)-induced albumin-bound Evans blue leak, in a dose-dependent manner. Immunofluorescence staining confirmed that TH reduced actin stress fiber formation while increasing cortical actin formation and colocalization of caveolin-1 and β-catenin in HUVECs. Signaling studies showed that HUVECs pretreated with TH significantly (p < 0.05) decreased intracellular calcium release, while sustaining the level of cAMP when challenged with H2O2. These results suggested that TH could inhibit H2O2-induced vascular hyperpermeability in vitro and in vivo by suppression of adherence junction protein redistribution via calcium and cAMP, which could have a therapeutic potential for diseases related to the increase of both oxidant and vascular permeability.

Matched MeSH terms: Cyclic AMP/metabolism
Extracellular calcium modulates insulin's action on enzymes controlling cyclic AMP metabolism in intact hepatocytes

Irvine F, Wallace AV, Sarawak SR, Houslay MD

Biochem. J., 1993 Jul 01;293 ( Pt 1):249-53.
PMID: 8392336

Absence of physiological concentrations of extracellular Ca2+ in the Krebs-Henseleit incubation buffer did not affect the ability of 10 nM glucagon (< 5%) to increase hepatocyte intracellular cyclic AMP concentrations, but severely ablated (by approximately 70%) the ability of 10 nM insulin to decrease these elevated concentrations. Cyclic AMP metabolism is determined by production by adenylate cyclase and degradation by cyclic AMP phosphodiesterase (PDE). In the absence of added extracellular Ca2+ (2.5 mM), insulin's ability to activate PDE activity was selectively compromised, showing a failure of insulin to activate two of the three insulin-stimulated activities, namely the 'dense-vesicle' and peripheral plasma-membrane (PPM) PDEs. In the absence of added Ca2+, insulin's ability to inhibit adenylate cyclase activity in intact hepatocytes was decreased dramatically. Vasopressin and adrenaline (+ propranolol) failed to elicit the activation of either the 'dense-vesicle' or the PPM-PDEs. The presence of physiological concentrations of extracellular Ca2+ in the incubation medium is shown to be important for the appropriate generation of insulin's actions on cyclic AMP metabolism.

Matched MeSH terms: Cyclic AMP/metabolism*
Fulltext The endogenous antimicrobial cathelicidin LL37 induces platelet activation and augments thrombus formation

Salamah MF, Ravishankar D, Kodji X, Moraes LA, Williams HF, Vallance TM, et al.

Blood Adv, 2018 Nov 13;2(21):2973-2985.
PMID: 30413433 DOI: 10.1182/bloodadvances.2018021758

Platelet-associated complications including thrombosis, thrombocytopenia, and hemorrhage are commonly observed during various inflammatory diseases such as sepsis, inflammatory bowel disease, and psoriasis. Despite the reported evidence on numerous mechanisms/molecules that may contribute to the dysfunction of platelets, the primary mechanisms that underpin platelet-associated complications during inflammatory diseases are not fully established. Here, we report the discovery of formyl peptide receptor 2, FPR2/ALX, in platelets and its primary role in the development of platelet-associated complications via ligation with its ligand, LL37. LL37 acts as a powerful endogenous antimicrobial peptide, but it also regulates innate immune responses. We demonstrate the impact of LL37 in the modulation of platelet reactivity, hemostasis, and thrombosis. LL37 activates a range of platelet functions, enhances thrombus formation, and shortens the tail bleeding time in mice. By utilizing a pharmacological inhibitor and Fpr2/3 (an ortholog of human FPR2/ALX)-deficient mice, the functional dependence of LL37 on FPR2/ALX was determined. Because the level of LL37 is increased in numerous inflammatory diseases, these results point toward a critical role for LL37 and FPR2/ALX in the development of platelet-related complications in such diseases. Hence, a better understanding of the clinical relevance of LL37 and FPR2/ALX in diverse pathophysiological settings will pave the way for the development of improved therapeutic strategies for a range of thromboinflammatory diseases.

Matched MeSH terms: Cyclic AMP/metabolism
Nitric oxide production by a human osteoblast cell line stimulated with Aggregatibacter actinomycetemcomitans lipopolysaccharide

Sosroseno W, Bird PS, Seymour GJ

Oral Microbiol. Immunol., 2009 Feb;24(1):50-5.
PMID: 19121070 DOI: 10.1111/j.1399-302X.2008.00475.x

Human osteoblasts induced by inflammatory stimuli express an inducible nitric oxide synthase (iNOS). The aim of the present study was to test the hypothesis that Aggregatibacter actinomycetemcomitans lipopolysaccharide stimulates the production of nitric oxide (NO) by a human osteoblast-like cell line (HOS cells).

Matched MeSH terms: Cyclic AMP/metabolism
Reduced nitric oxide-mediated relaxation and endothelial nitric oxide synthase expression in the tail arteries of streptozotocin-induced diabetic rats

Mokhtar SS, Vanhoutte PM, Leung SW, Suppian R, Yusof MI, Rasool AH

Eur J Pharmacol, 2016 Feb 15;773:78-84.
PMID: 26825543 DOI: 10.1016/j.ejphar.2016.01.013

Diabetes is associated with endothelial dysfunction, which is characterized by impaired endothelium-dependent relaxations. The present study aimed to examine the role of nitric oxide (NO), prostacyclin and endothelium-dependent hyperpolarization (EDH), in the relaxation of ventral tail arteries of rats under diabetic conditions. Relaxations of tail arteries of control and diabetic rats were studied in wire myograph. Western blotting and immunostaining were used to determine the presence of proteins. Acetylcholine-induced relaxations were significantly smaller in arteries of diabetic compared to control rats (Rmax; 70.81 ± 2.48% versus 85.05 ± 3.15%). Incubation with the combination of non-selective cyclooxygenase (COX) inhibitor, indomethacin and potassium channel blockers, TRAM 34 and UCL 1684, demonstrated that NO-mediated relaxation was attenuated significantly in diabetic compared to control rats (Rmax; 48.47 ± 5.84% versus 68.39 ± 6.34%). EDH-type (in the presence of indomethacin and NO synthase inhibitor, LNAME) and prostacyclin-mediated (in the presence of LNAME plus TRAM 34 and UCL 1684) relaxations were not significantly reduced in arteries of diabetic compared to control rats [Rmax: (EDH; 17.81 ± 6.74% versus 34.16 ± 4.59%) (prostacyclin; 15.85 ± 3.27% versus 17.23 ± 3.75%)]. Endothelium-independent relaxations to sodium nitroprusside, salbutamol and prostacyclin were comparable in the two types of preparations. Western blotting and immunostaining indicated that diabetes diminished the expression of endothelial NO synthase (eNOS), while increasing those of COX-1 and COX-2. Thus, since acetylcholine-induced NO-mediated relaxation was impaired in diabetes because of reduced eNOS protein expression, pharmacological intervention improving NO bioavailability could be useful in the management of diabetic endothelial dysfunction.

Matched MeSH terms: Cyclic AMP/metabolism
Cyclic-AMP-dependent proliferation of a human osteoblast cell line (HOS cells) induced by hydroxyapatite: effect of exogenous nitric oxide

Sosroseno W, Sugiatno E

Acta Biomed, 2008 Aug;79(2):110-6.
PMID: 18788505

BACKGROUND AND AIMS OF THE WORK: Nitric oxide (NO) has been reported to enhance the production of cAMP by hydroxyapatite (HA)-induced a human osteoblast cell line (HOS cells). The aim of the present study was to test the hypothesis that exogenous NO may up-regulate the proliferation of hydroxyapatite (HA)-induced HOS cells via the cyclic-AMP-protein kinase A (PKA) pathway.

Matched MeSH terms: Cyclic AMP/metabolism*
Regulatory actions of 3',5'-cyclic adenosine monophosphate on osteoclast function: possible roles of Epac-mediated signaling

Jeevaratnam K, Salvage SC, Li M, Huang CL

Ann N Y Acad Sci, 2018 Dec;1433(1):18-28.
PMID: 29846007 DOI: 10.1111/nyas.13861

Alterations in cellular levels of the second messenger 3',5'-cyclic adenosine monophosphate ([cAMP]i ) regulate a wide range of physiologically important cellular signaling processes in numerous cell types. Osteoclasts are terminally differentiated, multinucleated cells specialized for bone resorption. Their systemic regulator, calcitonin, triggers morphometrically and pharmacologically distinct retraction (R) and quiescence (Q) effects on cell-spread area and protrusion-retraction motility, respectively, paralleling its inhibition of bone resorption. Q effects were reproduced by cholera toxin-mediated Gs -protein activation known to increase [cAMP]i , unaccompanied by the [Ca2+ ]i changes contrastingly associated with R effects. We explore a hypothesis implicating cAMP signaling involving guanine nucleotide-exchange activation of the small GTPase Ras-proximate-1 (Rap1) by exchange proteins directly activated by cAMP (Epac). Rap1 activates integrin clustering, cell adhesion to bone matrix, associated cytoskeletal modifications and signaling processes, and transmembrane transduction functions. Epac activation enhanced, whereas Epac inhibition or shRNA-mediated knockdown compromised, the appearance of markers for osteoclast differentiation and motility following stimulation by receptor activator of nuclear factor kappa-Β ligand (RANKL). Deficiencies in talin and Rap1 compromised in vivo bone resorption, producing osteopetrotic phenotypes in genetically modified murine models. Translational implications of an Epac-Rap1 signaling hypothesis in relationship to N-bisphosphonate actions on prenylation and membrane localization of small GTPases are discussed.

Matched MeSH terms: Cyclic AMP/metabolism*
Fulltext The combination of mitragynine and morphine prevents the development of morphine tolerance in mice

Fakurazi S, Rahman SA, Hidayat MT, Ithnin H, Moklas MA, Arulselvan P

Molecules, 2013 Jan 04;18(1):666-81.
PMID: 23292329 DOI: 10.3390/molecules18010666

Mitragynine (MG) is the major active alkaloid found in Mitragyna speciosa Korth. In the present study, we investigated the enhancement of analgesic action of MG when combined with morphine and the effect of the combination on the development of tolerance towards morphine. Mice were administered intraperitoneally with a dose of MG (15 and 25 mg/kg b.wt) combined with morphine (5 mg/kg b.wt) respectively for 9 days. The antinociceptive effect was evaluated by a hot plate test. The protein expression of cyclic adenosine monophosphate (cAMP) and cAMP response element binding (CREB) was analyzed by immunoblot. Toxicological parameters especially liver and kidney function tests were assessed after the combination treatment with MG and morphine. The concurrent administration of MG and morphine showed significant (p < 0.05) increase in latency time when compared to morphine alone group and the outstanding analgesic effects in the combination regimens were maintained until day 9. For the protein expression, there was a significant increment of cAMP and CREB levels (p < 0.05) in group treated with 5 mg/kg morphine but there was no significant change of these protein expressions when MG was combined with morphine. There was a significant changes in toxicological parameters of various treated groups. The combination treatment of MG and morphine effectively reduce the tolerance due to the chronic administration of morphine.

Matched MeSH terms: Cyclic AMP/metabolism
Fulltext Rasd1, a small G protein with a big role in the hypothalamic response to neuronal activation

Greenwood MP, Greenwood M, Mecawi AS, Antunes-Rodrigues J, Paton JF, Murphy D

Mol Brain, 2016 Jan 07;9:1.
PMID: 26739966 DOI: 10.1186/s13041-015-0182-2

BACKGROUND: Rasd1 is a member of the Ras family of monomeric G proteins that was first identified as a dexamethasone inducible gene in the pituitary corticotroph cell line AtT20. Using microarrays we previously identified increased Rasd1 mRNA expression in the rat supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus in response to increased plasma osmolality provoked by fluid deprivation and salt loading. RASD1 has been shown to inhibit adenylyl cyclase activity in vitro resulting in the inhibition of the cAMP-PKA-CREB signaling pathway. Therefore, we tested the hypothesis that RASD1 may inhibit cAMP stimulated gene expression in the brain.
RESULTS: We show that Rasd1 is expressed in vasopressin neurons of the PVN and SON, within which mRNA levels are induced by hyperosmotic cues. Dexamethasone treatment of AtT20 cells decreased forskolin stimulation of c-Fos, Nr4a1 and phosphorylated CREB expression, effects that were mimicked by overexpression of Rasd1, and inhibited by knockdown of Rasd1. These effects were dependent upon isoprenylation, as both farnesyltransferase inhibitor FTI-277 and CAAX box deletion prevented Rasd1 inhibition of cAMP-induced gene expression. Injection of lentiviral vector into rat SON expressing Rasd1 diminished, whereas CAAX mutant increased, cAMP inducible genes in response to osmotic stress.
CONCLUSIONS: We have identified two mechanisms of Rasd1 induction in the hypothalamus, one by elevated glucocorticoids in response to stress, and one in response to increased plasma osmolality resulting from osmotic stress. We propose that the abundance of RASD1 in vasopressin expressing neurons, based on its inhibitory actions on CREB phosphorylation, is an important mechanism for controlling the transcriptional responses to stressors in both the PVN and SON. These effects likely occur through modulation of cAMP-PKA-CREB signaling pathway in the brain.

Matched MeSH terms: Cyclic AMP/metabolism
Fulltext Combinatorial effects of quercetin and sex-steroids on fluid and electrolytes' (Na+, Cl-, HCO3-) secretory mechanisms in the uterus of ovariectomised female Sprague-Dawley rats

Shahzad H, Giribabu N, Karim K, Kassim NM, Muniandy S, Salleh N

PLoS One, 2017;12(3):e0172765.
PMID: 28253299 DOI: 10.1371/journal.pone.0172765

Dysregulation of uterine fluid environment could impair successful reproduction and this could be due to the effect of environmental estrogens. Therefore, in this study, effect of quercetin, an environmental estrogen on uterine fluid and electrolytes concentrations were investigated under sex-steroid influence. Ovariectomised adult female Sprague-Dawley rats were given 10, 50 or 100mg/kg/day quercetin subcutaneously with 17-β estradiol (E) for seven days or three days E, then three days E plus progesterone (P) (E+P) treatment. Uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations were determined by in-vivo perfusion. Following sacrifice, uteri were harvested and levels of the proteins of interest were identified by Western blotting and Realtime PCR. Distribution of these proteins in the uterus was observed by immunofluorescence. Levels of uterine cAMP were measured by enzyme-linked immunoassay (EIA). Administration of quercetin at increasing doses increased uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations, but to the levels lesser than that of E. In concordant, levels of CFTR, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP in the uterus increased following increased in the doses of quercetin. Co-administration of quercetin with E caused uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations to decrease. In concordant, uterine CFTR, SLC26A6, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP decreased. Greatest effects were observed following co-administration of 10mg/kg/day quercetin with E. Co-administration of quercetin with E+P caused uterine fluid Na+ and HCO3- concentrations to increase but no changes in fluid secretion rate and Cl- concentration were observed. Co-administration of high dose quercetin (100 mg/kg/day) with E+P caused uterine CFTR, SLC26A6, AC, GPα/β and ENaC (α, β and γ) to increase. Quercetin-induced changes in the uterine fluid secretion rate and electrolytes concentrations could potentially affect the uterine reproductive functions under female sex-steroid influence.

Matched MeSH terms: Cyclic AMP/metabolism
Oleoyl-lysophosphatidylinositol enhances glucagon-like peptide-1 secretion from enteroendocrine L-cells through GPR119

Arifin SA, Paternoster S, Carlessi R, Casari I, Ekberg JH, Maffucci T, et al.

Biochim Biophys Acta Mol Cell Biol Lipids, 2018 09;1863(9):1132-1141.
PMID: 29883799 DOI: 10.1016/j.bbalip.2018.06.007

The gastrointestinal tract is increasingly viewed as critical in controlling glucose metabolism, because of its role in secreting multiple glucoregulatory hormones, such as glucagon like peptide-1 (GLP-1). Here we investigate the molecular pathways behind the GLP-1- and insulin-secreting capabilities of a novel GPR119 agonist, Oleoyl-lysophosphatidylinositol (Oleoyl-LPI). Oleoyl-LPI is the only LPI species able to potently stimulate the release of GLP-1 in vitro, from murine and human L-cells, and ex-vivo from murine colonic primary cell preparations. Here we show that Oleoyl-LPI mediates GLP-1 secretion through GPR119 as this activity is ablated in cells lacking GPR119 and in colonic primary cell preparation from GPR119-/- mice. Similarly, Oleoyl-LPI-mediated insulin secretion is impaired in islets isolated from GPR119-/- mice. On the other hand, GLP-1 secretion is not impaired in cells lacking GPR55 in vitro or in colonic primary cell preparation from GPR55-/- mice. We therefore conclude that GPR119 is the Oleoyl-LPI receptor, upstream of ERK1/2 and cAMP/PKA/CREB pathways, where primarily ERK1/2 is required for GLP-1 secretion, while CREB activation appears dispensable.

Matched MeSH terms: Cyclic AMP/metabolism

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