22498
The involvement of brain nicotinic acetylcholine receptors ( nAChRs ) in the neurotoxicological effects of soman , a potent acetylcholinesterase ( AChE ) inhibitor and a chemical warfare agent , is not clear .
 acetylcholine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 acetylcholine