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 the acute experiment TRI ( given i . p . ) does not antagonize the reserpine hypothermia in mice and does not potentiate the 5 - hydroxytryptophan head twitches in rats .
### Output Text:
In the acute experiment <span class="chemical">TRI</span> ( given i . p . ) does not antagonize the <span class="chemical">reserpine</span> hypothermia in mice and does not potentiate the <span class="chemical">5 - hydroxytryptophan</span> head twitches in rats . 