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: Based on the finding that VPU and VPA could protect the animals against pilocarpine - induced seizure it is suggested that the reduction of inhibitory amino acid neurotransmitters was comparatively minor and offset by a pronounced reduction of glutamate and aspartate .
### Output Text:
Based on the finding that <span class="chemical">VPU</span> and <span class="chemical">VPA</span> could protect the animals against <span class="chemical">pilocarpine</span> - induced seizure it is suggested that the reduction of inhibitory <span class="chemical">amino acid</span> neurotransmitters was comparatively minor and offset by a pronounced reduction of <span class="chemical">glutamate</span> and <span class="chemical">aspartate</span> . 