The Mucosecretion in the Submandibular Gland and the Role of Platelet-Activating Factor.

颌下腺的粘液分泌和血小板激活因子的作用。

• 批准号: 62570834
• 负责人: DOHI Toshihiro
• 金额: $ 1.22万
• 依托单位: Hiroshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62570834/
• 关键词: Platelet-activating factor; PAF; Mucin; Calcium; Acetylcholine; Submandibular gland; 血小板活性化因子; Platelet Activating Factor; 単離腺房細胞; ムチン分泌

Adrenergic and cholinergic stimulation of mucin release and platelet-activating factor (PAF) production and the role of Ca^<2+> have been investigated in the isolated dog submandibular gland cells.Stimulation of muscarinic cholinergic, alpha-adrenergic and beta-adrenergic receptors elicited mucin release from dispersed dog submandibular gland cells. The secretory response to Ach was much pronounced than those to adrenergic agonists, and largely dependent on the presence of extrace llul) Ca^<2+>, but the dependency on the extracellular Na^+ was slight. Ionomycin also stimulated mucin release from the cells. Neither muscarinic cholinergic agonists nor ionomycin were effective mucosecretagogues as beta-adrenergic agonists in rat submandibular gland cells. alpha-adrenoceptor-mediated release was decreased by chelating extracellular Ca^<2+> with EGTA. beta-adrenoceptor-mediated response was diminished by extensive exposure of cells to EGTA, due at least in part to the requirement of Ca^<2+> … More for -adrenocetor stimulation of cAMP formation. 8-br-cAMP stimulated ^<45>Ca^<2+> release from the cells preloaded with ^<45>Ca^<2+>.8-br-cAMP-induced mucin release was eliminated in ionomycin-pretreated cells. But not inhibited by chelating extracellular Ca^<2+> and by the treatment of the cells with TMB-8 or in the cells loaded with BAPTA. These results suggest that not only adrenergic system but also muscarinic cholinergic system may participate in the regulation of mucin release in dog submandibular gland, and also provide the possibility that, in addition to cAMP mediated mechanism, Ca^<2+>-dependent mechanisms may be involved in the mucosecretion in dog submandibular acini.Isolated dog submandibular gland cells synthesize platelet-activating factor (PAF) when stimulated with ACh. This production of PAF was concentration- and time-dependent, and was inhibited by pretreatments with anticholinergic agents. PAF accumulated in cells through prior stimulation with ACh vanished rapidly with the addition of atropine. Phenylmethylsulfonylfluoride produced an accumulation of PAF in non-stimulated cells and greatly potentiated further ACh-induced accumulation. PAF production and [^<14>C] arachidonic acid (AA) liberation induced by ACh were increased by higher concentrations of extracellular Ca^<2+>, and ACh failed to stimulate PAF formation in the absence of Ca^<2+>, though ACh still stimulated the liberation of [^<14>C] AA without Ca^<2+>. Both the calcium ionophor ionomycin in intact cells and Ca^<2+> (at concentrations <greater than or equal> 30 nM) in digitonin-permeabilized cells facilitated PAF formation. Lyso-PAF : acetyl-CoA acetyltransferase activity rapidly increased in cells incubated with ACh or ionomycin. These results suggest, at least, that the stimulation of a remodeling pathway is involved in the increased PAF synthesis induced by ACh. Dithiothreitol-insensitive cholinephosphotransferase activity was also activated by ACh. However, the activation of both enzymes by ACh was transient, in spite of the fact that ACh-stimulated PAF formation was continuous. This may suggest that additional mechanism (s) other than the activation of these enzymes play an important role in controlling PAF synthesis. The present study provides further evidence that exocrine submandibular gland cells of dogs have the capacity to increase PAF turnover upon stimulation in a Ca^<2+>-dependent manner and retain PAF within the cells partly associated with the membrane and partly released in the cytosol. Less

已在分离的狗颌下腺细胞中研究了粘蛋白释放和血小板激活因子（PAF）产生的肾上腺素能和胆碱能刺激以及Ca^2+的作用。刺激毒蕈碱胆碱能、α-肾上腺素能和β-肾上腺素能受体引起分散的狗颌下腺细胞释放粘蛋白。对Ach的分泌反应比对肾上腺素能激动剂的分泌反应明显得多，并且很大程度上依赖于额外的Ca 2+ 的存在，但对细胞外Na 2+ 的依赖是轻微的。离子霉素还刺激细胞释放粘蛋白。在大鼠颌下腺细胞中，毒蕈碱胆碱能激动剂和离子霉素都不是有效的粘液促分泌剂作为β-肾上腺素能激动剂。通过用EGTA螯合细胞外Ca 2+ 来减少α-肾上腺素受体介导的释放。 β-肾上腺素受体介导的反应因细胞广泛暴露于EGTA而减弱，这至少部分是由于β-肾上腺素受体刺激cAMP形成需要Ca^<2+...更多。 8-br-cAMP刺激的来自预先装载有^ 45 Ca 2+ 的细胞的^ 45 Ca 2+ 释放。在离子霉素预处理的细胞中消除了8-br-cAMP诱导的粘蛋白释放。但不被螯合细胞外Ca 2+ 和用TMB-8处理细胞或在负载BAPTA的细胞中抑制。这些结果提示,犬颌下腺粘液分泌不仅有肾上腺素能系统参与,毒蕈碱胆碱能系统也可能参与调节,同时也提供了除了cAMP介导的机制外,Ca^2+依赖性机制也可能参与犬颌下腺粘液分泌的可能性。分离的犬颌下腺细胞合成血小板活化因子。 (PAF) 当用乙酰胆碱刺激时。 PAF 的产生具有浓度和时间依赖性，并受到抗胆碱能药物预处理的抑制。通过预先用乙酰胆碱刺激而在细胞中积累的 PAF 在添加阿托品后迅速消失。苯甲基磺酰氟在未受刺激的细胞中产生 PAF 积累，并大大增强了 ACh 诱导的进一步积累。由ACh诱导的PAF产生和[^ 14 C]花生四烯酸(AA)释放因细胞外Ca ^ 2+ 浓度较高而增加，并且ACh在不存在Ca ^ 2+ 的情况下不能刺激PAF形成，尽管ACh在没有Ca ^ 2+ 的情况下仍刺激[^ 14 C]AA的释放。完整细胞中的钙离子载体离子霉素和毛地黄皂苷透化细胞中的Ca 2+ (浓度<大于或等于>30nM)均促进PAF形成。 Lyso-PAF：在与ACh或离子霉素一起孵育的细胞中，乙酰辅酶A乙酰转移酶活性迅速增加。这些结果至少表明，重塑途径的刺激与 ACh 诱导的 PAF 合成增加有关。二硫苏糖醇不敏感的磷酸胆碱转移酶活性也被乙酰胆碱激活。然而，尽管 ACh 刺激的 PAF 形成是连续的，但 ACh 对两种酶的激活是短暂的。这可能表明除了这些酶的激活之外的其他机制在控制PAF合成中发挥着重要作用。本研究提供了进一步的证据，表明狗的外分泌下颌下腺细胞具有在以Ca 2+ 依赖性方式刺激时增加PAF更新的能力，并且将PAF保留在细胞内，部分与膜相关并且部分在细胞质中释放。较少的

项目成果

Toshihiro Dohi et al.: "Calciumdepency of adrenergic and muscarinic cholinergic stimulation of mucin release from dog submandibular gland cells." Archives of Oral Biology.

Toshihiro Dohi 等人：“肾上腺素能和毒蕈碱胆碱能刺激狗颌下腺细胞粘蛋白释放的钙依赖。”

Toshihiro et al.: "Calciumーdepenent biosynthesis of plateletーactivating factor by the submandibular gland cells." Biochemical Journal.

Toshihiro 等人：“下颌下腺细胞钙依赖性血小板激活因子的生物合成。”

T. Dohi, K. Morita, S. Kitayama and A. Tsujimoto: "Calcium-dependent biosynthesis of platelet-activating factor by the submandibular gland cells." Biochemical Journal,.

T. Dohi、K. Morita、S. Kitayama 和 A. Tsujimoto：“下颌下腺细胞钙依赖性血小板激活因子生物合成。”

T. Dohi, H. Yamaki, K. Morita, S. Kitayama, H. Tsuru and A. Tsujimoto: "Calcium dependency of adrenergic and muscarinic cholinergic stimulation of mucin release from dog submandibular gland cells." Archives of Oral Biology.

T. Dohi、H. Yamaki、K. Morita、S. Kitayama、H. Tsuru 和 A. Tsujimoto：“狗颌下腺细胞粘蛋白释放的肾上腺素能和毒蕈碱胆碱能刺激的钙依赖性。”