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 : These results indicate that noradrenergic signaling via beta - adrenergic receptors is required for cocaine - induced anxiety in mice .
### Output Text:
CONCLUSIONS : These results indicate that noradrenergic signaling via beta - adrenergic receptors is required for <span class="chemical">cocaine</span> - induced anxiety in mice . 