Mechanism of carbachol-stimulated diacylglycerol formation in rat parotid acinar cells

Komabayashi, Takao; Yakata, Atsushi; Izawa, Tetsuya; Fujinami, Hiroyuki; Suda, Kazuhiro; Tsuboi, Masahiro

doi:10.1016/0922-4106(92)90022-n

Cited by 12 publications

(9 citation statements)

References 38 publications

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“…The present data demonstrate that endogenous and exogenous muscarinic agonists as well as a,adrenoceptor agonists cause a dose-dependent increase in tritium outflow from submandibular gland slices pre-labelled with [3H]choline. The results of our study support the idea that muscarinic and a,-adrenoceptor agonists stimulate a phosphatidylcholine specific phospholipase, as has previously been described in several cell lines and tissues (Exton 1988, Loffelholtz 1989, Billah & Anthes 1990 including the parotid gland (Komabayashi et al 1992).…”

Section: Discussionsupporting

confidence: 91%

“…T h e technique of [3H]choline labelling of neuronal acetylcholine stores in order to study the release of acetylcholine in brain tissue is well established (Richardson & (Komabayashi et al 1991(Komabayashi et al , 1992. This study suggests that this transduction mechanism is present in the submandibular gland, and that VIP is able to potentiate the effect of muscarine receptor stimulation on the phosphatidylcholine coupled phospholipase.…”

Section: Takuma and Ichida 1986)mentioning

confidence: 81%

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Breakdown of membrane choline‐phospholipids induced by endogenous and exogenous muscarinic agonist is potentiated by VIP in rat submandibular gland

Dunér-Engström

Fredholm

1993

Acta Physiologica Scandinavica

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The outflow of tritium from rat submandibular gland fragments, pre-labelled with [3H]choline, following electrical or pharmacological stimulation was studied. Electrical stimulation of the tissue increased the outflow of tritium in a frequency dependent manner. Atropine treatment decreased the electrically-induced release, indicating that the outflow did not reflect acetylcholine from nerve endings, but was largely brought about by postsynaptic receptors. In agreement with this hypothesis, treatment with noradrenaline or carbachol induced a dose dependent increase in tritium outflow from the gland fragments which could be blocked by prazosin or atropine, respectively. Moreover, analysis of the tissue-associated tritium revealed an incorporation primarily in the lipid fraction of the tissue (almost 80%), of which about 90% was in phosphatidylcholine, indicating that this was the source of the tritium outflow. Pre-incubation with vasoactive intestinal polypeptide (VIP), which coexists with acetylcholine in the parasympathetic neurons innervating the submandibular gland, increased the carbachol-induced tritium overflow significantly. The effect of VIP could be imitated by the adenylyl cyclase stimulator forskolin, which increased the carbachol-stimulated tritium efflux in a dose dependent manner. Taken together, our results suggests that muscarinic- and alpha 1-receptor agonists may activate a phospholipase coupled to phosphatidylcholine hydrolysis in the rat submandibular gland. Endogenous acetylcholine released from parasympathetic nerve endings appear to activate this mechanism. Furthermore, VIP treatment, and the concomitant cAMP-accumulation, potentiates the acetylcholine induced phosphatidylcholine hydrolysis, demonstrating a new type of interaction between the classical transmitter acetylcholine and the co-stored neuropeptide VIP.

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Section: Discussionsupporting

confidence: 91%

Section: Takuma and Ichida 1986)mentioning

confidence: 81%

Breakdown of membrane choline‐phospholipids induced by endogenous and exogenous muscarinic agonist is potentiated by VIP in rat submandibular gland

Dunér-Engström

Fredholm

1993

Acta Physiologica Scandinavica

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“…Moreover, we obtained similar results after stimulation with sub stance P or carbachol (12,35). Perhaps, phosphatidyl ethanolamine hydrolysis may not be associated directly with DAG generation in the parotid gland.…”

Section: Discussionsupporting

confidence: 73%

Sustained Changes in Acetylcholine and Amino Acid Contents of Brain Regions Following Microsphere Embolism in Rats

Taguchi

Miyake

Tanonaka

et al. 1993

Japanese Journal of Pharmacology

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ABSTRACT-The kinetics and mechanism of sn-1,2-diacylglycerol (DAG) formation induced by isoprenaline were studied in rat parotid acinar cells. DAG accumulation induced by 100 pM isoprenaline reached its maximum at 1 min, rapidly decreased (about 50%) at 5 min and then remained constant for 30 min. DAG accumulation 1 min after isoprenaline treatment was dose-dependent. Either propranolol or phentolamine inhibited isoprenaline-stimulated DAG accumulation in a dose-dependent manner. Addition of a vasoactive intestinal polypeptide, forskolin, or dibutyryl cyclic AMP had no effect on DAG accumula tion. Isoprenaline did not cause the release of [3H]choline or [3H]ethanolamine metabolites into the medium. Based on the kinetics of DAG formation and [32P]phosphoinositide breakdown, we conclude that isoprenaline-induced DAG formation was mainly related to the hydrolysis of [32P]phosphatidylinositol 4,5 bisphosphate ([32P]PIP2). These results suggest that the effect of isoprenaline on DAG formation is mediated by a,-adrenoceptor activation, that it is not related to the increase in cyclic AMP, and that it is closely related to PIP2 hydrolysis.

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“…Thus, PC hydrolysis is mediated through phospholipase C and/or D (12); however, no conclusions regarding phospholipase stimulation were reached in this study on parotid acinar cells. We have observed that carbachol stimulated PC hydrolysis is related to the activation of phospholipase C in this system (24). In the present study, both A23187 and PDBu stimulated the release of…”

Section: Analysis Of [3h]choline Metabolites Released Into the Mediumsupporting

confidence: 52%

Ca2+ Ionophore and Phorbol Ester Stimulate Diacylglycerol Formation and Phosphatidylcholine Hydrolysis in Rat Parotid Acinar Cells

Komabayashi¹,

Yakata²,

Izawa³

et al. 1992

Japanese Journal of Pharmacology

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ABSTRACT-We investigated the effects of A23187 and phorbol 12,13-dibutyrate (PDBu) on sn-1,2 diacylglycerol (DAG) accumulation and phosphatidylcholine (PC) hydrolysis in rat parotid acinar cells. Both A23187 and PDBu, in concentration ranges of 0.001-0.1 uM, stimulated DAG accumulation and PC hydrolysis in a time and concentration-dependent manner. Treatment with A23187 and PDBu stimulated the release of [3H]choline and [3H]phosphocholine into the medium, indicating [3H]PC hy drolysis is due to the activation of phospholipases C and D; however, [3H]phosphatidylethanolamine hydrolysis was not indicated. These releases were unaffected by the addition of glucose 6-phosphate, a phosphatase inhibitor. Staurosporine, a protein kinase C inhibitor, significantly inhibited the DAG accumulation and the PC hydrolysis stimulated by these agents. Combinations of A23187 and PDBu potentiated the stimulatory effect which each of these agents alone had on DAG accumulation and PC hydrolysis. This mode of action was additive but not synergistic. These results suggest that DAG accu mulation induced by A23187 and PDBu is related to the PC hydrolysis mediated via the activation of phospholipases C and D, and that it is not related to phosphatidylethanolamine hydrolysis. Keywords:Parotid acinar cells, A23187, Phorbol 12,13-dibutyrate, sn-1,2-Diacylglycerol accumulation, Phosphatidylcholine hydrolysisAgonist binding to its receptor leads to phosphatidyl inositol 4,5-bisphosphate breakdown into sn-1,2-diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate (1,4,5 IP3) via activation of inositol phospholipid-specific phospholipase C coupled with a GTP binding protein; DAG activates protein kinase C and 1,4,5-IP3 mobilizes Ca 2+ from the endoplasmic reticulum (1-4). These events are thought to play an important role in stimulus-secretion coupling (5 7).DAG was shown to be derived from phosphoino sitides, phosphatidylcholine (PC), and other lipids (7 10), but the relationship between DAG generation and their source during agonist stimulation is not fully understood. This may be due to the complexity of the kinetics of DAG formation; e.g., the kinetics of DAG formation varies with the agonist and the cell type. Re cently, PC hydrolysis has gained much attention, be cause DAG generated by protein kinase C-dependent PC-specific phospholipase C can provide a sustained activation of protein kinase C (11). In many cell types, CA 2+ ionophore or phorbol ester stimulates PC hy drolysis through phospholipase C and/or D and results in DAG accumulation. However, the mode (phospho lipase C, phospholipase D) by which these agents elicit DAG formation from PC varies with the cell type (12). As reviewed by Billah and Anthes (12), there are many reports concerning PC hydrolysis induced by Ca 2+ ionophore and phorbol esters, but the mechanism of PC hydrolysis in this system remains unknown.We therefore examined the effects of A23187 and phorbol 12,13-dibutyrate (PDBu) on DAG accumula tion and PC hydrolysis in rat parotid acinar cells. These results provide ...

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Mechanism of carbachol-stimulated diacylglycerol formation in rat parotid acinar cells

Cited by 12 publications

References 38 publications

Breakdown of membrane choline‐phospholipids induced by endogenous and exogenous muscarinic agonist is potentiated by VIP in rat submandibular gland

Breakdown of membrane choline‐phospholipids induced by endogenous and exogenous muscarinic agonist is potentiated by VIP in rat submandibular gland

Sustained Changes in Acetylcholine and Amino Acid Contents of Brain Regions Following Microsphere Embolism in Rats

Ca2+ Ionophore and Phorbol Ester Stimulate Diacylglycerol Formation and Phosphatidylcholine Hydrolysis in Rat Parotid Acinar Cells

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