Immunocytochemical evidence for an afferent GABAergic neurotransmission in the guinea pig vestibular system.
To implicate gamma-aminobutyric acid (GABA) as an afferent neurotransmitter (AN), the localization of GABA synthesizing and degradation enzymes; L-glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) was investigated by light and electron microscopy immunocytochemistry in guinea pig vestibular cristae and ganglion cells (GC). GAD-like immunoreactivity was exclusively confined to the sensory hair cell (HC) cytoplasm, suggesting that GAD synthesizes GABA in the HC. GABA-T like immunoreactivity was found within HC, nerve calyces, nerve fibers, and GC, suggesting its participation in terminating transmitter action. These results demonstrate the existence of a GABAergic system in the guinea pig vestibule and strongly support GABA as a vestibular AN.
López
I
I
Departamento de Neurociencias, UNAM, México, D.F.
Wu
J Y
JY
Meza
G
G
D000818:Animals; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology / Q000502:physiology; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000201:enzymology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008854:Microscopy, Electron; D009475:Neurons, Afferent / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D014722:Vestibule, Labyrinth / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase