氨对胆囊收缩素抑制大鼠胃酸分泌的影响

Effects of ammonia on the cholecystokinin-induced inhibition of gastric acid secretion in rats

目的旨在观察氨对胆囊收缩素（ＣＣＫ）抑制大鼠胃酸分泌的影响及其可能机制。方法３０只Ｗｉｓｔａｒ大鼠随机分为对照组（１５只）和实验组（１５Ｒ），后者给予０．１％氨水处理的饲料和含０．０１％氨的饮用水。２个月后采用胃内连续灌注引流法观察ＣＣＫ－８Ｓ及ＣＣＫ－８Ｓ合用ｌｏｘ（特异性ＣＣＫ－Ａ受体拮抗剂）对五肽胃泌素刺激的大鼠胃酸分泌变化，同时测定血浆生长抑素（ＳＳＴ）水平和胃Ｄ细胞数量变化。结果实验组大鼠的胃氨水平（８．００±１．８８ｕｇ／ｇ）明显高于对照组（１．２９±０．５６ｕｇ／ｇ，Ｐ＜０．００１），但其胃Ｄ细胞数（２．７８±０．４个／高倍镜）与对照组（２．５８±０．３８个／高倍镜）比较，差异无显著性（Ｐ＞０．０５）。ＣＣＫ－８Ｓ可使对照组大鼠血浆ＳＳＴ水平升高并部分抑制五肽胃泌素刺激的胃酸分泌，这种作用可被ｌｏｘ所拮抗；然而，ＣＣＫ－８Ｓ虽可使实验组大鼠血浆ＳＳＴ水平升高，但不抑制其胃酸分泌，施予ｌｏｘ对酸分泌也无进一步的影响。结论上述结果表明，ＣＣＫ抑制胄酸分泌主要是经过ＳＳＴ介导的，氨干扰ＣＣＫ－ＳＳＴ的抑酸效应可能是氨影响了靶细胞对ＳＳＴ的敏感性。

Obj ective This study was aimed to investigate the effects of ammonia on CCK-induced inhibition of pentagastrin-stimulated acid secretion in rats. Method Thirty Wistar rats were randomly divided into experimental and control groups. The rats were given either 0. 1% ammonia-treated forages or 0.01 × ammonia solution containing 0. 1 . ammonia chloride or normal forages. Two monthos after treatment, effects of CCK-8(4nmol/kg.h,iv) and CCK-8 with loxiglumide (1mg/kg,ip. a CCK-A specific antagonist) on the pentagastrin-stimulated acid secretion were observed with continuous recording of acid secretion. The plasma concentration of somatostatin (SST), number of D cells and level of ammonia in the gastric mucosa were detected respectively . Results The mean level of ammonia was significantly higher in treated group than in controls (8.00 ×1 .86ug/g and 1.29±0.56ug/g, respectively, P<0.001). However, there were no significant pathologic changes in the two groups and the number of D cells (2. 78 ±0.41/HF and 2.68±0.38/HF, respectively, P>0.05). Pentagastrin significantly stimulated acid output in all rats, which could be inhibited by CCK followed by increased plasma levels of SST in control rats . In turn, the inhibition of CCK could be antagonised by loxiglumide. However, CCK failed to inhibit the pentagstrin-stimulated acid secretion in treated rats, although SST was released after infusion of CCK . Co- nclusion Ammonia per se has little damaging effect on the normal gastric mucosa in rats, but it does disturb the inhibition of acid secretion induced by C CK , which may be due to the irresponsiveness of parietal cells to .SST.