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: After 6 months of hyperprolactinemia , dopamine ( DA ) concentrations in the median eminence ( ME ) increased by 84 % over the control group .
### Output Text:
After 6 months of hyperprolactinemia , <span class="chemical">dopamine</span> ( <span class="chemical">DA</span> ) concentrations in the median eminence ( ME ) increased by 84 % over the control group . 