Glutamate neurotoxicity in cochlear spiral ganglion cell of newborn guinea pigs

Objective: To study the neurotoxicity in neonate guinea pigs spiral ganglion cell of glutamate at different doses , modifying the current glutamate dependent deaf model. METHODS Four groups of guinea pigs were given sodium glutamate 0,1,2,4 g·kg -1 ·d -1 ip. respectively for 7 days. After 35 days with sufficient food, PR and brainstem auditory evoked potential (BAEP) of guinea pigs were tested . And the cochlear spiral ganglion was measured by Nissl stain method . RESULTS The mortality of the four groups was 0/10,2/10,4/10,20/20 respectively .BAEP reaction threshold ,G0 group was 43.5±3.4dB,G1 group 43.8±9.4 dB, G2 group 67.3±23.3 dB. The density of ganglion cells were 4345.7±241.4 cell/mm 2,4215.4±295.2 cell/mm 2,1997.5±1019.8 cell/mm 2 respectively. The differences between G2 and other groups were significant,P0.01. CONCLUSION Glutamate treatment causes dose dependent degeneration of cochlea spiral ganglion cell in newborn guinea pigs , and 2g·kg -1 ·d -1 ,ip. is a suitable dose for producing the glutamate dependent deaf model.