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 aim of this study was to examine the role of metabotropic glutamate receptor 5 ( mGluR5 ) in the toxic action of methamphetamine on dopaminergic neurones in rats .
### Output Text:
The aim of this study was to examine the role of metabotropic <span class="chemical">glutamate</span> receptor 5 ( mGluR5 ) in the toxic action of <span class="chemical">methamphetamine</span> on dopaminergic neurones in rats . 