Dzidic A, Prgomet C, Mohr A, Meyer K, Bauer J, Meyer H H D, Pfaffl M W
Physiology, Center of Life and Food Science, Technical University of Munich, Freising-Weihenstephan, Germany.
J Vet Med A Physiol Pathol Clin Med. 2006 May;53(4):163-9. doi: 10.1111/j.1439-0442.2006.00809.x.
Mycophenolic acid (MPA) is a mycotoxin commonly found as Penicillium genus secondary metabolite in feedstuffs and silages. Feeding with MPA contaminated silages may modulate the immune system in the farm animals and can cause appetite lost, ketosis, paralysis and abortion. The aim of the present study was to characterize the long-term MPA effect on both the inosine monophosphate dehydrogenase (IMPDH) isoforms I and II mRNA expression in white blood cells (WBC) and various tissue of healthy sheep. In treated animals 300 mg MPA/day/sheep was applied. In all investigated tissues the IMPDH I and II mRNA was abundant: WBC, spleen, thymus, ileum, jejunum, kidney, liver, pharyngeal and mesenterial lymph node. An efficiency-corrected relative quantification of the IMPDH types I and II isoforms mRNA were performed by normalizing with the constant reference gene expression of beta-actin. High IMPDH I mRNA expression levels were seen in kidney > mesenterial lymph node > jejunum > spleen > pharyngeal lymph node. Medium and low abundance was found in ileum > WBC > liver > thymus. Type II mRNA was highly expressed in liver > thymus > jejunum. In pharyngeal lymph node > spleen > ileum > mesenterial lymph node > kidney > WBC medium to low IMPDH II mRNA concentrations were detected. Under MPA treatment the IMPDH I mRNA expression was not significantly regulated in WBC, only trends of down- and upregulation were observed. Surprisingly in jejunum an upregulation could be observed (P < 0.05). In pharyngeal lymph node a tendency to downregulation was shown. This may be due to frequent ruminant activities and frequent exposition of MPA to the pharyngeal lymph nodes. In contrast to type I mRNA expression, IMPDH II mRNA was significantly downregulated in ileum (3.4-fold, P < 0.01) and tendencies in downregulation could be seen in jejunum (5.1-fold, P = 0.14). In addition, significant downregulation of IMPDH II gene expression over the entire feeding experiment could be shown in WBC of MPA-treated animals compared with untreated animals (P < 0.05). In conclusion, the recent study demonstrates that feeding sheep with MPA-contaminated silage did not induce IMPDH I mRNA expression in various tissues and blood, except in jejunum, but has suppressive effects on IMPDH II mRNA expression in WBC and ileum.
霉酚酸（MPA）是一种霉菌毒素，常见于饲料和青贮饲料中，是青霉属的次生代谢产物。用受MPA污染的青贮饲料喂养可能会调节农场动物的免疫系统，并可能导致食欲丧失、酮病、瘫痪和流产。本研究的目的是表征长期MPA对健康绵羊白细胞（WBC）和各种组织中肌苷单磷酸脱氢酶（IMPDH）I型和II型同工型mRNA表达的影响。在处理的动物中，每天每只绵羊施用300毫克MPA。在所有研究的组织中，IMPDH I和II mRNA都很丰富：白细胞、脾脏、胸腺、回肠、空肠、肾脏、肝脏、咽和肠系膜淋巴结。通过用β-肌动蛋白的恒定参考基因表达进行归一化，对IMPDH I型和II型同工型mRNA进行了效率校正的相对定量。在肾脏>肠系膜淋巴结>空肠>脾脏>咽淋巴结中观察到高IMPDH I mRNA表达水平。在回肠>白细胞>肝脏>胸腺中发现中等和低丰度。II型mRNA在肝脏>胸腺>空肠中高表达。在咽淋巴结>脾脏>回肠>肠系膜淋巴结>肾脏>白细胞中检测到中等至低的IMPDH II mRNA浓度。在MPA处理下，白细胞中IMPDH I mRNA表达没有受到显著调节，仅观察到下调和上调趋势。令人惊讶的是，在空肠中可以观察到上调（P < 0.05）。在咽淋巴结中显示出下调趋势。这可能是由于反刍动物活动频繁以及MPA频繁暴露于咽淋巴结。与I型mRNA表达相反，IMPDH II mRNA在回肠中显著下调（3.4倍，P < 0.01），在空肠中可以看到下调趋势（5.1倍，P = 0.14）。此外，与未处理的动物相比，在MPA处理的动物的白细胞中，在整个喂养实验中IMPDH II基因表达显著下调（P < 0.05）。总之，最近的研究表明，用受MPA污染的青贮饲料喂养绵羊，除空肠外，不会在各种组织和血液中诱导IMPDH I mRNA表达，但对白细胞和回肠中的IMPDH II mRNA表达有抑制作用。
