4343
The administration of yeast hydrolysate ( YH - control ; no heat treatment , YH - 1 ; heat treatment at 140 degrees C , and YH - 2 ; heat treatment at 160 degrees C ) significantly increased mRNA expression of cocaine - and amphetamine - regulated transcript ( CART ) compared with control rats ( saline administration ) .
 cocaine, amphetamine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 cocaine, amphetamine