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: The reduction of amphetamine hyperactivity induced by DSP4 was blocked by pretreatment with the noradrenaline - uptake blocking agent , desipramine , which prevents the neurotoxic action of DSP4 .
### Output Text:
The reduction of <span class="chemical">amphetamine</span> hyperactivity induced by <span class="chemical">DSP4</span> was blocked by pretreatment with the <span class="chemical">noradrenaline</span> - uptake blocking agent , <span class="chemical">desipramine</span> , which prevents the neurotoxic action of <span class="chemical">DSP4</span> . 