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: A comparable overexpression of Pgp in the BBB was obtained after pilocarpine - induced seizures in wild - type Wistar rats .
### Output Text:
A comparable overexpression of Pgp in the BBB was obtained after <span class="chemical">pilocarpine</span> - induced seizures in wild - type Wistar rats . 