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: Intracerebroventricular injection of U - II also caused an increase in : food intake at doses of 100 and 1 , 000 ng / mouse , water intake at doses of 100 - 10 , 000 ng / mouse , and horizontal locomotion activity at a dose of 10 , 000 ng / mouse .
### Output Text:
Intracerebroventricular injection of <span class="chemical">U - II</span> also caused an increase in : food intake at doses of 100 and 1 , 000 ng / mouse , water intake at doses of 100 - 10 , 000 ng / mouse , and horizontal locomotion activity at a dose of 10 , 000 ng / mouse . 