| Background and ObjectivePresently, Iodine deficiency disorders (IDD) have been mostly controlled after supplement of iodine salt for more than twenty years. However, it is found that the new patients of sub-cretinism still frequently appeared. Selenium is indispensable to selenium protein and is the structural element and activity center of many enzymes in vivo. For example, glutathione peroxidase (GSH-Px), deiodinase I II III (ID I II III), selenium protein P, selenium protein W are typical selenium protein or enzymes which are important for brain development. Therefore, selenium deficiency was considered as a possible nosogenetic factor of the sub-cretinism besides iodine deficiency. The EGFR/MAPK (mitogen-activated protein kinase; ERK1/2) pathway consists of a protein kinase cascade linking growth and differentiation signals to transcription in the nucleus. The importance of this pathway in both growth and development has been demonstrated. In this study, we investigate the effect of EGFR/MAPK signal transduction and nucleus gene c-Fos and 5-HT1AR protein expression on the postnatal 4th day and 21th day hippocampus, cortex and entire brainin selenium deficiency rat, iodine deficiency rat, both selenium and iodine deficiency rat, and compared with controls using the third generation rat brains from established selenium deficiency rat model.Materials and MethodsThe third generation rat brains of established selenium deficiency rat model were used as experimental objects to comparatively observe the protein expression of EGFR 5-HTR, a-MAPK a-PERKl/2 c-Fos in rebirth rat entire brain and hippocampus ,cortex of the postnatal 4th day and 21thday rats brain in control group(selenium and iodine supply, CTL), iodine deficiency group(I) ,selenium deficiency group (Se~) , selenium and iodine deficiency group(SeT). Morphology localization and protein expression were detected respectively by immunohistochemistry and Western blot method. Moreover, Hemi-fix quantitiy analysis by Bio-Rad Quantity4.5.2 software was utilized on protein expression.ResultsResults I:The effect of selenium deficiency on MAPK signal transduction pathway on rat brain of third generation postnatal 4th day l.The expression of EGFR protein: Using immunohistochemistry method, the expression of EGFR protein of hippocampal CAKno significant differences) ~CA3(P<0.01) area were significantly lower in I" ,Se"and SeT group than in CTL group and was the lowest in SeT group . And the expression of EGFR protein of cortex were significantly lower in I" ,Se"and SeT group than in CTL group(P<0. 01) and was the lowest in Se'group. Using Western blot method, the expression of EGFR protein of the postnatal 4th day rats entire brain has no significant differences.2. The expression of MAPK and p- ERK1/2 protein:Immunohistochemistry and Western blot (entire brain) methods found the expression of MAPK protein has no significant differences in hippocampal CA1~CA3 area and cortex.The expression of p-MAPK(p-ERKl/2) of hippocampal CA1~CA3 area and cortex deteced by immunohistochemistry method were significantly lower in I" ,Se~and SeT group than in CTL group(P<0. 01), and was the lowest in Se" group .Moreover, according to the results of Western blot method ,it was observed that the expression of p-ERKl(p-P44MAPK) and p-ERK2(p-P42MAPK) of entire brain were significantly lower in I" ,Se~and SeT group than in CTL group(P<0. 01), and was the lowest in Se" group.3. The expression of c-Fos nucleus protein:Using immunohistochemistry method, the expression of c-Fos protein of hippocampal CA1 area in 1" , Se" (P<0. 05) group and of hippocampal CA3 area in I" , SeT group were feebly higher than that of CTL group. And the expression of c-Fos protein of the postnatal 4th day rat's entire brain has no significant differences by Western blot method.4. The expression of 5-HTR protein: Using immunohistochemistry method, in cortex, the expression of 5-HTR protein has no significant differences, but in hippocampal CA1 ~ CA3, its expression were sig...
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