1722
In this study , laser scanning confocal microscopy was used to examine the effects of Pb ( 2 + ) on intracellular and endoplasmic reticulum free calcium concentration ( [ Ca ( 2 + ) ] ( i ) and [ Ca ( 2 + ) ] ( ER ) ) in cultured neonatal rat hippocampal neurons and their possible antagonism by methionine choline ; understanding these effects would help explain the lead - induced cognitive and learning dysfunction and explore efficient safety and relief strategies .
 Chemical: Pb ( 2 + ); Chemical: calcium; Chemical: Ca ( 2 + ); Chemical: Ca ( 2 + ); Chemical: methionine choline
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 ( 2 + ); Chemical: calcium; Chemical: Ca ( 2 + ); Chemical: Ca ( 2 + ); Chemical: methionine choline