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: Repeated trimipramine induces dopamine D2 / D3 and alpha1 - adrenergic up - regulation .
### Output Text:
Repeated <span class="chemical">trimipramine</span> induces <span class="chemical">dopamine</span> D2 / D3 and alpha1 - adrenergic up - regulation . 