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 the present study the role of glial activation and post synaptic toxicity in ICV Streptozotocin ( STZ ) induced memory impaired rats was explored .
### Output Text:
In the present study the role of glial activation and post synaptic toxicity in ICV <span class="chemical">Streptozotocin</span> ( <span class="chemical">STZ</span> ) induced memory impaired rats was explored . 