TRIPHENYL PHOSPHITE-INDUCED NEUROPATHY IN THE AVIAN FOREBRAIN - A SILVER IMPREGNATION STUDY OF THE VISUAL AND AUDITORY SYSTEMS OF THE JAPANESE-QUAIL

Single subcutaneous injections of triphenyl phosphite (TPP) (62.5-500m g/kg body weight) were made in the Japanese quail (Coturnix coturnix j aponica). The extent and density of resultant central nervous system d egeneration were mapped by using the Fink-Heimer silver impregnation m ethod to selectively impregnate degenerating axons and terminals. In a ddition to resulting in degeneration in the medulla and cerebellum, ex posure to TPP also resulted in axonal and terminal degeneration in spe cific midbrain and forebrain nuclei and tracts related to the auditory and visual systems. Auditory system nuclei containing axonal and term inal degeneration included the lateral mesencephalic nucleus, pars dor salis, the nucleus ovoidalis, and area L of Rose in the caudal neostri atum. Anterograde degeneration was also noted in nuclei and tracts rel ated to the visual tectofugal system - the brachium of the superior co lliculus, nucleus rotundus, pretectal nuclei, and the ectostriatum. Ad ditional degeneration was noted in the paleostriatum primitivum, dorso -intermediate posterior thalamic nucleus, lateral spiriform nucleus, a nd the pedunculopontine tegmental nucleus, all of which are related to visuomotor control. These results indicate that in the Japanese quail , exposure to TPP yields anterograde degeneration in nuclei and tracts involved with the transmission and processing of higher order visuomo tor, visual sensory, and auditory sensory information. (C) 1994 Intox Press, Inc.