Uptake of putative neurotransmitters in the organ of Corti

In vitro uptake of putative neurotransmitters into the organ of Corti of the guinea pig was studied by autoradiography. After incubation in 3H-glycine the label was heaviest over the inner hair cell, but was not confined to the synaptic region of the cell. After incubation in 3H-GABA, 3H-glutamate and 3H-aspartate, heavy labeling was seen over the fibers and terminals of the efferent olivocochlear bundle. Leucine, an amino acid not thought to be a neurotransmitter, was uniformly taken up by all cochlear structures. The fact that GABA, glutamate and aspartate are taken up into efferents, which are almost certainly cholinergic, suggests that high affinity uptake of these substances is not restricted to terminals in which these substances are released as neurotransmitters.