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: While nocistatin ( 0 . 5 - 5 . 0 nmol mouse - 1 , i . c . v . ) administered 30 min before spontaneous alternation performance or the training session of the passive avoidance task , had no effect on spontaneous alternation or passive avoidance behaviours , a lower per cent alternation and shorter median step - down latency in the retention test were obtained in nociceptin ( 1 . 5 and / or 5 . 0 nmol mouse - 1 , i . c . v . ) - treated normal mice .
### Output Text:
While <span class="chemical">nocistatin</span> ( 0 . 5 - 5 . 0 nmol mouse - 1 , i . c . v . ) administered 30 min before spontaneous alternation performance or the training session of the passive avoidance task , had no effect on spontaneous alternation or passive avoidance behaviours , a lower per cent alternation and shorter median step - down latency in the retention test were obtained in <span class="chemical">nociceptin</span> ( 1 . 5 and / or 5 . 0 nmol mouse - 1 , i . c . v . ) - treated normal mice . 