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: Depletion of dopamine in the striatum was also antagonized when LY274614 was given after the injection of amphetamine ; LY274614 protected when given up to 4 hr after but not when given 8 or 24 hr after amphetamine .
### Output Text:
Depletion of <span class="chemical">dopamine</span> in the striatum was also antagonized when <span class="chemical">LY274614</span> was given after the injection of <span class="chemical">amphetamine</span> ; <span class="chemical">LY274614</span> protected when given up to 4 hr after but not when given 8 or 24 hr after <span class="chemical">amphetamine</span> . 