In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In animals pretreated with microinjections of isoniazid , 150 micrograms , an inhibitor of activity of the GABA - synthesizing enzyme , L - glutamic acid decarboxylase , into the substantia nigra pars reticulata ( SNR ) , bilaterally , non - convulsant doses of pilocarpine , 100 and 200 mg / kg , resulted in severe motor limbic seizures and status epilepticus .
### Output Text:
In animals pretreated with microinjections of <span class="chemical">isoniazid</span> , 150 micrograms , an inhibitor of activity of the <span class="chemical">GABA</span> - synthesizing enzyme , <span class="chemical">L - glutamic acid</span> decarboxylase , into the substantia nigra pars reticulata ( SNR ) , bilaterally , non - convulsant doses of <span class="chemical">pilocarpine</span> , 100 and 200 mg / kg , resulted in severe motor limbic seizures and status epilepticus . 