EXOGENOUS GM1 GANGLIOSIDE EFFECTS ON CONDUCTIVE AND SENSORINEURAL HEARING LOSSES

Both CBA/J mice with neonatal cochlea removals and CBA/J mice with neo natal atresias of the external auditory meatus have significantly smal ler ventral cochlear nucleus volumes and significantly smaller neurona l somata of their ventral cochlear nucleus. The volume reduction of th e ventral cochlear nuclei is greater in the mice with cochlea removals , but the soma area reduction is greater in the mice with external aud itory meatus atresias. GM1 gangliosides were subcutaneously injected d aily into a group of CBA/J mice with conductive hearing loss caused by neonatal removals of their left external auditory meatus, and into a group of CBA/J mice unilaterally deafened by left cochlea removals. In the mice with conductive hearing loss, the ganglioside treatment sign ificantly ameliorated the atrophy of spiral ganglion neurons, ventral cochlear nucleus neurons, and ventral cochlear nucleus volume. In unil aterally deafened mice, the ganglioside treatment had no measurable ef fect on the atrophy of ventral cochlear nucleus neurons or of ventral cochlear nucleus volume. It is suggested that GM1 ganglioside treatmen t potentiates growth factors which sustain spiral ganglion integrity a nd that this sustained activity of the spiral ganglion in turn maintai ns the integrity of the cochlear nuclei.