7175
The goal of the study was to investigate the roles of mu and kappa opioid receptors in systemic ghrelin - mediated regulation of the mesolimbic dopamine system .
 Chemical: dopamine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: dopamine