This study examined the combined effects of administration of exogenous GM1 @entity4163 and electrical stimulation on the cochlear nucleus (CN) of @entity468 deafened neonatally by @entity2167 drugs. Five normal hearing adult @entity468 served as controls. Another 12 @entity468 were deafened bilaterally by daily injections of @entity5154 (60 mg/kg) for 17-21 days after birth until auditory brainstem testing demonstrated profound @entity393 . Six of the deaf animals comprised the GM1 group, which received daily injections of GM1 @entity4163 (30 mg/kg) for 28-38 days during the period after profound @entity2319 was confirmed, and prior to receiving a cochlear implant. The non-GM1 group (n=6) received no treatment during this interim period. All the deafened animals underwent unilateral cochlear implantation at 6-9 weeks postnatal and received several months (mean duration, 32 weeks) of chronic electrical stimulation (4 h/day, 5 days/week). Stimulation was delivered by intracochlear bipolar electrodes, using electrical signals that were designed to be temporally challenging to the central auditory system. Results showed that in the neonatally deafened animals, both the GM1 and non-GM1 groups, the volume of the CN was markedly reduced (to 76% of normal), but there was no difference between the animals that received GM1 and those that did not. The cross sectional areas of spherical cell somata in both GM1 and non-GM1 groups also showed a highly significant reduction in size, to < or =75% of normal after neonatal deafening. Moreover, in both the GM1 and non-GM1 groups, the spherical cells in the CN ipsilateral to the implanted cochlea were significantly larger (6%) than cells in the control, unstimulated CN. Again, however, there was no significant difference between the GM1 group and the non-GM1 group in spherical cell size. These results contrast sharply with previous reports that exogenous GM1 prevents @entity528 after neonatal conductive @entity393 and partially prevents @entity528 when administered immediately after @entity2167 drug deafening in adult animals. Taken together, findings to date suggest that GM1 may be effective in preventing degeneration only if the GM1 is administered immediately at the time @entity393 occurs.

Does exogenous GM1 XXXX enhance the effects of electrical stimulation in ameliorating @entity528 ?

@entity2167 :: ('MESH:D006311', 'Disease') :: ['ototoxic'] @entity2319 :: ('MESH:D003638', 'Disease') :: ['deafness'] @entity5154 :: ('MESH:D009355', 'Chemical') :: ['neomycin sulfate'] @entity393 :: ('MESH:D034381', 'Disease') :: ['hearing loss'] @entity4163 :: ('CHEBI:28892', 'Chemical') :: ['ganglioside'] @entity468 :: ('9685', 'Species') :: ['cats'] @entity528 :: ('MESH:D009410', 'Disease') :: ['CN degeneration', 'spiral ganglion cell degeneration']
@entity4163 :: (CHEBI:28892,Chemical) :: ['ganglioside']
