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: Pretreatment with reserpine ( 1 mg / kg ) 24 h before the observation test produced increases in vacuous chewing movements and tongue protrusion , as well as increases in tremor and catalepsy , whereas MK - 801 ( 0 . 1 mg / kg ) injection 90 min before the test reversed the effects of reserpine .
### Output Text:
Pretreatment with <span class="chemical">reserpine</span> ( 1 mg / kg ) 24 h before the observation test produced increases in vacuous chewing movements and tongue protrusion , as well as increases in tremor and catalepsy , whereas <span class="chemical">MK - 801</span> ( 0 . 1 mg / kg ) injection 90 min before the test reversed the effects of <span class="chemical">reserpine</span> . 