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: Damage of substantia nigra pars reticulata during pilocarpine - induced status epilepticus in the rat : immunohistochemical study of neurons , astrocytes and serum - protein extravasation .
### Output Text:
Damage of substantia nigra pars reticulata during <span class="chemical">pilocarpine</span> - induced status epilepticus in the rat : immunohistochemical study of neurons , astrocytes and serum - protein extravasation . 