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 addition , carteolol did not evoke 5 - HT1A receptor - stimulating behavioral signs such as flat body posture and forepaw treading and did not inhibit 5 - hydroxytryptophan - induced head twitch in rats .
### Output Text:
In addition , <span class="chemical">carteolol</span> did not evoke 5 - HT1A receptor - stimulating behavioral signs such as flat body posture and forepaw treading and did not inhibit <span class="chemical">5 - hydroxytryptophan</span> - induced head twitch in rats . 