20572
It had been observed that in Pb group the spatial memory , the induce level of LTP , the serum SOD level decreased , the LDH release level , the neurons apoptosis level , the serum MDA level increased , while in the Se supplements groups , the spatial memory , the induce level of LTP increased significantly .
 Chemical: Pb; Chemical: MDA; Chemical: Se
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Pb; Chemical: MDA; Chemical: Se