Fastigiovestibular projections in the rat: retrograde tracing coupled withgamma amino-butyric acid and glutamate immunohistochemistry

In this study, a double labeling technique using retrograde tracing with pr otein-gold complex (gold-HRP) in conjunction with a gamma amino-butyric aci d (GABA) and glutamate immunohistochemical procedure was performed to ident ify GABA (GABA-IR) and glutamate (Glu-IR) immunoreactive neurons in the cer ebellar fastigial nucleus (FN) that projects to the vestibular nuclei (VN). The results show that FN neurons projecting to the VN consist of both GABA -IR and Glu-IR neurons with a predominance of glutamatergic ones. Because G ABAergic neurons in the cerebellar nuclei project to the inferior olive (10 ), double retrograde labeling experiments were performed with injections of gold-HRP in the 10 and of biotilynated dextran amine in the VN. This showe d that the GABA-IR fastigiovestibular neurons project by axon collaterals t o both the VN and the 10. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.