关键词: 肠道, 5-羟色胺, 免疫组织化学, 季节, 食物质量, 长爪沙鼠

Abstract: To explore the relationship between the density of 5-Hydroxytryptamine (5-HT) cells and seasonal environmental
conditions,localizations and comparisons of 5-HT-immunoreactive (IR)cells in the five portions (duodenum,small intestine, caecum,colon and rectum) of the gut in Mongolian gerbils (Meriones unguiculatus) were studied in both late November (winter) in 2003 and July (summer)in 2004, respectively,using an avidin-biotin-peroxidase complex immunohistochemical method. 5-HT-IR cells were distributed mainly in the basal portion of the epithelium of the gut and epithelium of the gut gland,and showed similar morphological features both in winter and in summer. Most of 5-HT-IR cells were round or oval in shape,while fewer were long-bar,cone,or irregular in shape. In winter,the number of 5-HT-IR cells was the highest in the small intestine,fewer in the duodenum,caecum and rectum,and the lowest in the colon. In summer,the highest densities of 5-HT-IR cells were located in the duodenum and small intestine,densities were lower and similar in the other portions of the gut. The distribution of 5-HT-IR cells in different seasons may be related to the seasonal changes of food components. Except for the duodenum and colon,the cell densities of the other portions of the gut in winter were significantly higher than those of summer,which is beneficial for enhancing digestion and assimilation,may be an adaptive strategy to deal with differences in food quality and the increased food intakes needed to survive winter successfully. Both morphological features and seasonal dynamics of 5-HT-IR cells suggested that,at the cellular level,the gut of Mongolian gerbils can respond to complex environmental conditions,and this has adaptive regulation functions.

Key words: Food quality, Gut, 5-Hydroxytryptamine (5-HT), Immunohistochemistry, Mongolian gerbils (Meriones unguiculatus), Season