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Selective retrograde transport of nipecotic acid, a GABA analog, labels a subpopulation of gerbil olivocochlear neurons
Author(s) -
Ryan Allen F.,
Keithley Elizabeth M.,
Schwartz Ilsa R.,
Wang ZhiXian
Publication year - 1992
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903260303
Subject(s) - gerbil , efferent , nipecotic acid , cochlea , superior olivary complex , efferent neuron , hair cell , biology , axoplasmic transport , neuroscience , afferent , inner ear , anatomy , cochlear nucleus , nucleus , central nervous system , neurotransmitter , medicine , ischemia
Perfusion of the gerbil cochlea with micromolar quantities of 3 H‐γ‐aminobutyric acid (GABA) results in rapid, selective labeling of 50–60% of the olivocochlear (OC) efferent terminals on afferent dendrites beneath the inner hair cells, and all of the efferent terminals beneath the outer hair cells. In order to identify the neurons from which these GABA‐accumulating terminals originate, the cell bodies were localized by using retrograde transport of 3 H‐nipecotic acid, a metabolically inert GABA analog. With survival times of 6–30 hours after cochlear injection, myelinated OC efferent fibers and cell bodies were well labeled, with the greatest number being labeled at 12‐18 hours. All of the labeled neurons belonged to the medial OC system, and no lateral OC neurons were labeled. It is concluded that the GABA‐accumulating endings in the gerbil cochlea arise from medial OC neurons, and therfore that medial OC efferent neurons in this species project to both inner and outer hair cell regions. © 1992 Wiley‐Liss, Inc.