猕猴发育过程中肠肝组织血管活性肠肽及其受体的变化

本文旨在探讨猕猴发育过程中血管活性肠肽(vasoactive intestinal polypeptide,VIP)及其受体在肠肝组织的变化。通过手术途径获得胚胎6月、新生2 d、新生45 d和成年猕猴的回肠、肝脏、门静脉和外周血等标本,应用放射免疫分析法测定各标本中的VIP含量;通过免疫组化方法观察VIP在肠、肝组织内的分布;利用原位杂交法检测VIP受体1(VIP receptor 1,VIPR1)的表达。结果显示:(1)胚胎6月的猕猴小肠VIP含量为(20．7±14．3)ng／mg蛋白;小肠绒毛根部及黏膜下层可见少量的VIP阳性染色颗粒;在发育过程中,小肠VIP含量逐渐增加,成年期时达(514．8±49．2)ng／mg蛋白,较胚胎6月显著增加(P<0．01)。(2)成年猕猴小肠VIP主要分布于绒毛隐窝部、黏膜下层神经及环、纵行肌间神经丛及环行肌,在发育过程中相应部位的VIPR1表达逐渐上调。(3)肝脏在发育过程中VIP及VIPR1含量逐渐降低。(4)发育的各个时期,小肠组织的VIP含量均明显高于肝脏组织,门静脉VIP水平也始终高于外周血。结果提示,小肠绒毛隐窝部、黏膜下层神经及环、纵行肌间神经内VIP及VIPR1含量足在出生以后才迅速增加的;不论是在胚胎还是成年期,VIP均不在肝中代谢和分解,VIPR1仅见于胚胎肝脏血管。

Changes of vasoactive intestinal polypeptide and vasoactive intestinal polypeptide receptor 1 in small intestine and liver during macaque development

The present study was aimed to investigate the changes of vasoactive intestinal polypeptide (VIP) and VIP receptor 1 (VIPR1) in small intestinal and hepatic tissues during macaque development. The tissue samples of small intestine, liver and blood samples from peripheral and portal vein of 4 macaques of 6-month fetus, 2-day neonate, 45-day neonate and adult were obtained after anesthetization. The concentration of VIP in blood or tissues of macaques was measured by radioimmunoassay. The distribution of VIP in small intestinal or hepatic tissues was visualized by immunohistochemical staining. The expression of VIPR1 was detected by in situ hybridization. The results showed that: (1) VIP concentration in intestinal tissue of 6-month fetus was (20.7+/-14.3) ng/mg protein, and a few VIP-positive nerve fibers first appeared in intestinal villus root and submucosal layer but not in muscle layer. The intestinal concentration of VIP increased gradually with macaque development and reached (514.8+/- 49.2) ng/mg protein in adult, significantly higher than that in 6-month fetus (P<0.01). (2) In adult animal, VIP-positive nerve fibers became thicker and gradually extended into the mucosal crypt, submucosal layer nerve, myenteric nerve plexus of annular muscle and indulge muscle, and annular muscle. Correspondingly, the expression of VIPR1 in intestine was up-regulated during development. (3) On the contrary, the levels of VIP and VIPR1 in liver were gradually decreased during development. (4) VIP concentration in small intestinal tissue was higher than that in hepatic tissue during development. The VIP level in portal vein was also significantly higher than that in peripheral blood during development. In conclusion, the levels of VIP and VIPR1 in mucosal crypt, submucosal layer nerve, myenteric nerve plexus of annular muscle and indulge muscle increase rapidly after birth. Most of VIP from intestinal tract is degraded in portal vein before entering liver, suggesting that VIP does not metabolize and decompose in liver, and that VIPR1 is only present in embryo hepatic blood vessels.