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These data suggest that increased nitric oxide production after a neurotoxic regimen of methamphetamine results from increased nitric oxide synthase activity , rather than an induction of mRNA , and that constitutively expressed neuronal nitric oxide synthase is the most likely source of nitric oxide after methamphetamine administration .
 Chemical: nitric oxide; Chemical: methamphetamine; Chemical: nitric oxide; Chemical: nitric oxide; Chemical: nitric oxide; Chemical: methamphetamine
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: nitric oxide; Chemical: methamphetamine; Chemical: nitric oxide; Chemical: nitric oxide; Chemical: nitric oxide; Chemical: methamphetamine