Identifying candidate serum biomarkers of exposure to tunicamycins in rats using two-dimensional electrophoresis

A model for chronic corynetoxins poisoning has been established in rats exposed to the toxicologically bioequivalent inhibitor of N-linked glycosylation the tunicamycins. Consumption of corynetoxins in contaminated pasture can result in the often fatal neurological disease of grazing livestock annual ryegrass toxicity (ARGT). Corynetoxins may also threaten human health as potential contaminants of the food supply via grain or products derived from subclinically exposed animals. The serum proteomes of four dose groups plus a control group following 6, 9, and 12 months dietary tunicamycins exposure were compared by one-dimensional electrophoresis. Numerous differences were observed between the control and the highest dose group (40.5 mug tunicamycins/kg of body weight/day), designated as High). Accordingly, these samples were further examined using two-dimensional electrophoresis. Thirty-three protein spots were found to be differentially displayed between the Control and High dose sera based on univariate statistics (p < 0.05 for log(10) transformed normalized volumes) and significant fold-changes in spot volume (+/-2.3-fold as determined by posthoc power analysis). Identities for 28 spots were obtained by MALDI-TOF MS corresponding to 13 different proteins. An increasing population of carbohydrate deficient transferrin was identified in the High dose sera using a combination of antibody and lectin detection and confirmed by ESI-IT MS/MS. The functionalities of other identified proteins were consistent with the oxidative stress and acute phase responses. The biomarkers identified in this study may not only play a useful role in diagnosing toxin exposure but could be helpful in identifying new treatment strategies for ARGT and equivalent human diseases.