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: CONCLUSIONS : Sub - chronic low dose GVG potentiates and extends the inhibition of cocaine - induced increases in dopamine , effectively reducing cumulative exposures and the risk for VFDS .
### Output Text:
CONCLUSIONS : Sub - chronic low dose <span class="chemical">GVG</span> potentiates and extends the inhibition of <span class="chemical">cocaine</span> - induced increases in <span class="chemical">dopamine</span> , effectively reducing cumulative exposures and the risk for VFDS . 