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

摘要： 为探讨季节性环境对长爪沙鼠肠道5-羟色胺(5-hydroxytryptamine,5-HT)细胞密度动态的影响,于2003
年11 月(冬季)和2004 年7 月(夏季),采用卵白素-生物素-过氧化物酶复合物(avidin-biotin-peroxidase complex,
ABC)免疫组织化学法,对其肠道5-HT 细胞进行了定位研究。结果显示:5-HT 细胞主要分布于肠上皮基
底部和肠腺上皮中,多呈圆形或椭圆形,少数呈长棒状、锥体形或不规则形,其形态学特征无季节性差异。冬
季在小肠密度最高,十二指肠、盲肠和直肠其次,结肠最低;夏季在小肠和十二指肠密度最高,其它各段密度
相似,这可能与其食物质量的季节性变化有关。除十二指肠和结肠外,冬季肠道各段的密度都高于夏季,这有
利于提高处理和消化食物的能力,是对冬季食物质量和摄食量增加的适应。5-HT 细胞的形态学特征和季节动态
说明,长爪沙鼠肠道在细胞水平上可对环境条件的变化产生反应,具有适应性调节的能力。

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