“The analgesic effect of morphine was antagonized in mice by intracerebroventricular pretreatment with taurine , gamma-aminobutyric acid (GABA) or glycine and was potentiated by ethylene glycol tetra-acetic acid (EGTA) but not altered by L-glutamate or L-aspartate.”
“The selective depletion of 45Ca2+ from synaptic vesicles observed with morphine administration was significantly inhibited by taurine injection (1.2 mumol/brain, i.vt.)”
“These results suggest that antagonism of morphine analgesia by taurine may be caused by blockade of the morphine-induced inhibition of both ATP-dependent synaptosomal 45Ca2+ uptake and changes in synaptic vesicular 45Ca2+ localization, while the antagonism by GABA was not associated with synaptosomal Ca2+.”