关键词: 肠道, 生长抑素, P 物质, 年龄, 长爪沙鼠

Abstract: Gastrointestinal hormones play important roles in regulating the digestive processes of small mammals,and
change with age. Substance P (SP)and somatostatin (SS)immunoreactive (IR)cells have opposite functions:the former promotes motility of the small intestine,and the latter acts as an inhibitor. To clarify age-dependent variation in distribution, as well as interactive features of SS and SP-IR cells along the gut in the Mongolian gerbils (Meriones unguiculatus), localization and comparison of both endocrine cells in the five portions (duodenum,small intestine,caecum,colon and rectum)of the gut in young,adult,and old gerbils were studied in winter using avidin-biotin-peroxidase complex immunohistochemical method. Both endocrine cells showed similar morphological features at different ages,being round,oval, shuttle,cone,or irregular in shape. The distribution of SS-IR cells tended to be narrower with increased age. SS-IR cells were found mainly in the duodenum and small intestine for all ages,and no immunoreactivity was found in the colon and the rectum in old gerbils. In the caecum,old gerbils showed higher densities of SS-IR cells than did young and adult gerbils, but no significant differences were found in any other portion of the gut. SP-IR cells displayed the highest densities in the colon,caecum,and rectum for young,adult and old gerbils,respectively,and no immunoreactivity was found in the colon and the rectum for adult gerbils. Different from SS-IR cells,SP-IR cells displayed significant differences for the each portion of gut for different ages. In conclusion,SS and SP-IR cells showed different distributions and age-dependent developmental features along the gut of Mongolian gerbils,which may be related to food quality and the opposing physiological functions of the two endocrine cells.

Key words: Age, Gut, Mongolian gerbil (Meriones unguiculatus), Somatostatin (SS), Substance P (SP)