Chang F Y, Lee S D, Doong M L, Wang P S
Division of Gastroenterology, Taipei Veterans General Hospital, 201 Shih-Pai Road, Section 2, Taipei, Taiwan 11217, ROC.
Hepatogastroenterology. 2001 Jan-Feb;48(37):143-6.
BACKGROUND/AIMS: Both calcium and calcitonin have been involved in mediating gastrointestinal motility. Using a thyroidectomized rat model the present study tried to determine which one of them was essential for normal small intestinal transit.
Adult Sprague-Dawley male rats simultaneously received thyroidectomy or a sham operation plus a laparotomy for duodenal tubing. After two-week housing, a small intestinal transit study was conducted via geometric center computation of radioactivities of the intestinal segments counted from intraduodenal feeding of radiochromium. Before feeding, these rats were i.p. injected with saline or human calcitonin in the doses of 0.1, 1 and 10 microM/kg, respectively. Another group of Tx rats received i.v. infusion of saline or CaCl2 for 30 min before motility study.
Thyroidectomization effectively delayed transit compared to the sham-operated controls (3.59 +/- 0.15 vs. 2.98 +/- 0.32, P < 0.05). High doses of calcitonin treatment in thyroidectomized rats further inhibited transit (P < 0.01), whereas calcitonin did not restore the suppressed calcium level. Delayed transit in thyroidectomized rats was restored after calcium infusion (2.95 +/- 0.22 vs. 3.78 +/- 0.42, P < 0.05) while their hypocalcemia was already corrected.
Thyroidectomization disturbs small intestinal transit, while peripheral calcitonin replacement further inhibits transit. Since calcium replacement enables to restore small intestinal transit, it is apparent that calcium rather than calcitonin is essential for normal small intestinal transit.
背景/目的：钙和降钙素均参与介导胃肠动力。本研究采用甲状腺切除大鼠模型，试图确定它们之中哪一种对正常小肠转运至关重要。
成年雄性Sprague-Dawley大鼠同时接受甲状腺切除术或假手术加剖腹十二指肠插管术。饲养两周后，通过对十二指肠内注入放射性铬后计数的肠段放射性活度进行几何中心计算来开展小肠转运研究。在喂食前，分别给这些大鼠腹腔注射生理盐水或剂量为0.1、1和10微摩尔/千克的人降钙素。另一组甲状腺切除大鼠在动力研究前静脉输注生理盐水或氯化钙30分钟。
与假手术对照组相比，甲状腺切除有效地延迟了转运（3.59±0.15对2.98±0.32，P<0.05）。甲状腺切除大鼠接受高剂量降钙素治疗进一步抑制了转运（P<0.01），而降钙素并未恢复被抑制的钙水平。甲状腺切除大鼠在输注钙后延迟的转运得到恢复（2.95±0.22对3.78±0.42，P<0.05），而它们的低钙血症已得到纠正。
甲状腺切除扰乱小肠转运，而外周给予降钙素替代物会进一步抑制转运。由于补充钙能够恢复小肠转运，显然钙而非降钙素对正常小肠转运至关重要。
