Elsasser T H, Fayer R, Rumsey T S, Hammond A C
U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705.
Domest Anim Endocrinol. 1990 Oct;7(4):537-50. doi: 10.1016/0739-7240(90)90011-n.
The effects of parasitic infection on plasma and tissue content of immunoreactive somatostatin (SRIF) were studied in 4-mo old male calves inoculated with the protozoan Sarcocystis cruzi. Because feed intake significantly decreased (70%) in infected calves around day 28 postinfection (pi), concomitant with the asexual replication of S. cruzi and outward expression of clinical signs, the relative contributions of infection and associated reduction in nutrition on plasma SRIF were evaluated. Treatment groups were: noninfected ad libitum fed (C), infected (250,000 S. cruzi oocysts per os) ad libitum fed (I) and noninfected calves pairfed to the level of intake of each infected calf (PF). Mean plasma concentrations of SRIF (pg/ml) on day 30 pi were: C, 224 +/- 22; I, 742 +/- 150; PF, 246 +/- 31 (effect of infection P less than .05). In another study, SRIF was measured in plasma and in pancreatic, duodenal, jejunal and ileal tissue extracts from normal and S. cruzi infected calves. Plasma and tissue samples were collected on day 42 pi. Mean plasma SRIF were 2.5 times higher in infected than control calves. Plasma insulin and insulin-like growth factor 1 was lower in infected v control calves (P less than .02). Plasma glucagon was similar between groups. Duodenal (P less than .05) and jejunal (P less than .02) SRIF content was higher in infected than control calves. Chromatography of tissue extracts on Sephadex G-50 revealed that the increase in SRIF was accounted for, in part, by molecular forms larger than cyclic SRIF-14. Data suggest that peripheral SRIF is increased in calves during S. cruzi infection. The increase in SRIF is not solely related to plane of nutrition. Altered levels of gut SRIF(s) may be associated with perturbed metabolic regulation in parasitized animals through direct effects on the gut.
研究了寄生虫感染对4月龄雄性犊牛血浆和组织中免疫反应性生长抑素（SRIF）含量的影响，这些犊牛接种了原生动物克氏肉孢子虫。由于感染犊牛在感染后约第28天采食量显著下降（70%），这与克氏肉孢子虫的无性繁殖及临床症状的外在表现同时发生，因此评估了感染及相关营养减少对血浆SRIF的相对影响。治疗组包括：未感染自由采食组（C）、感染组（经口接种250,000个克氏肉孢子虫卵囊）自由采食组（I）以及与每头感染犊牛采食量水平配对饲养的未感染犊牛组（PF）。感染后第30天血浆SRIF的平均浓度（pg/ml）为：C组，224±22；I组，742±150；PF组，246±31（感染的影响P＜0.05）。在另一项研究中，测定了正常犊牛和感染克氏肉孢子虫犊牛的血浆以及胰腺、十二指肠、空肠和回肠组织提取物中的SRIF。在感染后第42天采集血浆和组织样本。感染犊牛的血浆SRIF平均水平比对照犊牛高2.5倍。感染犊牛的血浆胰岛素和胰岛素样生长因子1低于对照犊牛（P＜0.02）。各组间血浆胰高血糖素相似。感染犊牛的十二指肠（P＜0.05）和空肠（P＜0.02）SRIF含量高于对照犊牛。组织提取物在葡聚糖G - 50上的色谱分析显示，SRIF的增加部分是由大于环状SRIF - 14的分子形式引起的。数据表明，克氏肉孢子虫感染期间犊牛外周SRIF增加。SRIF的增加并非仅与营养水平有关。肠道SRIF水平的改变可能通过对肠道的直接作用与寄生动物代谢调节紊乱有关。
