Changes of vasoactive intestinal polypeptide and vasoactive intestinal polypeptide receptor 1 in small intestine and liver during macaque development / 生理学报

ABSTRACT

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.