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: Furthermore , yohimbine increased baseline startle amplitude in the LES , while mCPP suppressed baseline startle in both the LES and FPS and PTZ suppressed baseline startle in the FPS .
### Output Text:
Furthermore , <span class="chemical">yohimbine</span> increased baseline startle amplitude in the LES , while <span class="chemical">mCPP</span> suppressed baseline startle in both the LES and FPS and <span class="chemical">PTZ</span> suppressed baseline startle in the FPS . 