pharmacological and electrophysiological studies have implicated the biogenic amines serotonin and norepinephrine , and the endogenous opioid peptides enkephalin and dynorphin , in those controls ( basbaum and fields , 1978 , 1984 ; basbaum et al. , 1983 ; basbaum , 1985 ) .
C0205753
endogenous opioid peptides
C0013355
dynorphin