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: Hyperprolactinemia was induced by treatment with haloperidol , a dopamine receptor antagonist , and Palkovits ' microdissection technique in combination with high - performance liquid chromatography was used to measure neurotransmitter concentrations in several areas of the brain .
### Output Text:
Hyperprolactinemia was induced by treatment with <span class="chemical">haloperidol</span> , a <span class="chemical">dopamine</span> receptor antagonist , and Palkovits ' microdissection technique in combination with high - performance liquid chromatography was used to measure neurotransmitter concentrations in several areas of the brain . 