Role of a novel neurppeptide, orexin,in the central regulation of gastric acid secretion

新型神经肽食欲素在胃酸分泌中枢调节中的作用

• 批准号: 11670471
• 负责人: OKUMURA Toshikatsu
• 金额: $ 1.15万
• 依托单位: Asahikawa Medical College
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670471/
• 关键词: orexin; orexin receptor; orexin analogue; gatsric acid; vagus nerve; disulfide band; binding affinity; structure-funtion relationship; orexinorexin受容体; オレキシン; 迷走神経; 脳相刺戟胃分泌; 摂食因子; 外側視床下部; 神経ペプチド

We examined first the effect of intracisternal injection of orexin-A on gastric acid secretion in rats. Intracisternal injection of orexin-A dose-dependently stimulated gastric acid output by the pylorus-ligation method. In contrast, intraperitoneal administration of orexin-A failed to stimulate acid, secretion, suggesting that orexin-A acts in the brain to stimulate gastric acid secretion. The stimulation of gastric secretion was not observed in the vagotomyzed rats, indicating that the vagus nerve mediates the orexin-induced acid secretion Orexin-A is a neuropeptide consisting 33 amino acids with two intrachain disulfide bonds, namely Cys6-Cys12 and Cys7-Cys14. In contrast, orexin-B, a peptide containing 28 amino acids without disulfide bond, which has no stimulatory action of gastric acid. Intracisternal injection of orexin-A but not orexin-B or orexin-A (15-33) that does not contain both disulfide bonds stimulated gastric acid secretion in pylonis-ligated conscious rats. The abilit … More y of the stimulation of gastric acid output was less in three alanine-substituted orexin-A, [Ala 6, 12]orexin-A, [Ala 7, 14]orexin-A and [Ala 6, 7, 12, 14]orexin-A, than orexin-A, Orexins-induced calcium increase was measured in CHO-K1 cells expressing OX1R or OX2R. Orexin-A induced a transient increase in [Ca2+]i in CHO-K1/OX1R cells in a dose-dependent manner. EC50 values for OX1R of orexin-A, orexhi-B or orexin-A (15-33) was 0.068, 0.69 or 4.1 nM, respectively, suggesting that peptides containing no disulfide bonds have lower potency for the receptor. Agonistic activity for OX1R of the three orexin-A analogues with modification of one or both disulfide bonds was significantly reduced as compared with that of orexin-A. EC50 values for OX2R of orexin-A and orexin-B was almost equal but potency for the receptor of orexin-A (15-33) and three alanine substituted orexin-A was less than that of orexin-A. A significant inverse relationship between gastric acid output and EC50 values for OX1R but not OX2R was observed. These results suggested that the orexin-A-induced acid stimulation requires OX1R activation and that disulfide bonds in orexin-A may have a key role in the receptor activation. Less

我们首先检查了脑池内注射食欲素-A对大鼠胃酸分泌的影响。通过幽门结扎法，脑池内注射食欲素A剂量依赖性地刺激胃酸分泌。相反，腹膜内施用食欲素-A不能刺激胃酸分泌，表明食欲素-A在脑中起作用以刺激胃酸分泌。在迷走神经切断大鼠中未观察到胃分泌的刺激，表明迷走神经介导食欲素诱导的酸分泌食欲素-A是由33个氨基酸组成的神经肽，具有两个链内二硫键，即Cys6-Cys12和Cys7-Cys14。而食欲素B是一种由28个氨基酸组成的肽，不含二硫键，对胃酸无刺激作用。在幽门结扎的清醒大鼠中，脑池内注射食欲素-A而不是食欲素-B或不含两个二硫键的食欲素-A（15 - 33）刺激胃酸分泌。能力 ...更多信息 [Ala 6，12] orexin-A、[Ala 7，14] orexin-A和[Ala 6，7，12，14] orexin-A对胃酸分泌的刺激作用均小于orexin-A。Orexin-A以剂量依赖性方式诱导CHO-K1/OX1R细胞内[Ca2 +] i瞬时升高。食欲素-A、食欲素-B或食欲素-A（15 - 33）的OX1R的EC50值分别为0.068、0.69或4.1 nM，表明不含二硫键的肽对受体的效力较低。与orexin-A相比，具有一个或两个二硫键修饰的三种orexin-A类似物对OX1R的激动活性显著降低。Orexin-A和Orexin-B对OX2R的EC 50值几乎相等，但对Orexin-A（15 - 33）和三个丙氨酸取代的Orexin-A的受体的效力小于Orexin-A。观察到胃酸排出量与OX1R而非OX2R的EC 50值之间存在显著的负相关关系。这些结果表明，食欲素-A诱导的酸刺激需要OX1R激活，食欲素-A中的二硫键可能在受体激活中起关键作用。少

项目成果

Okumura T, et al.: "Requirement of intact disulfide bonds in orexin-A-induced stimulation of gastric acid secretion that is mediated by OX1 receptor activation."Biochem Biophys Res Commun. (in press). (2001)

Okumura T 等人：“在食欲素 A 诱导的 OX1 受体激活介导的胃酸分泌刺激中需要完整的二硫键。”Biochem Biophys Res Commun。

Yamada H, et. al.: "Inihbition of food intake by intracisternal injection of anti-orexin antibody in fasted rats"Biochem Biophys Res Commun. 267. 527-531 (2000)

山田 H 等。

Okumura T, et. al.: "Requirement of intact disulfide bonds in orexin-A-induced stimulation of gastric acid secretion that is mediated by OX1 receptor activation"Biochem Biophys Res Commun. 280. 976-981 (2001)

奥村T等。

Okumura T, et al.: "Requirement of intact disulfide bonds in orexin-A-induced stimulation of gastric acid secretion that is mediated by OXi receptor activation"Biochem Biophys Res Commun. 280. 976-981 (2001)

Okumura T 等人：“在 OXi 受体激活介导的食欲素 A 诱导的胃酸分泌刺激中需要完整的二硫键”Biochem Biophys Res Commun。

Takahashi N, et. al.: "Stimulation of gastric acid secretion by centrally administered orexin-A in consious rats"Biochem Biophys Res Commun. 254. 623-627 (1999)

高桥 N 等。