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: In addition , rats that experienced SE exhibited CCR2 - labeling in populations of hypertrophied astrocytes , especially in CA1 and dentate gyrus .
### Output Text:
In addition , rats that experienced SE exhibited CCR2 - labeling in populations of hypertrophied astrocytes , especially in CA1 and dentate gyrus . 