3643
It has been demonstrated that stimulation of the pontomesencephalic parabrachial region ( PBR ) by microinjection of cholinergic drugs or electricity in the cat produces potent pain suppression which is not antagonized by the opiate antagonist , naloxone .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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