[Effects of GLAST gene knockout on phenotype and hearing in mice]

To investigate the effects of glutamate aspartate transporter (GLAST)deletion on the normal auditory function of mice.

We hybridized GLAST^+/- mice with C57BL/6J background and identified the genotypes of their offspring by agarose gel electrophoresis. 9-10-week-old mice were selected to detect the expression of GLAST protein in the cochlea by immunofluorescence staining and to verify the knockout results(n=3). The changes in weight from 7 days to 30 days after birth and the 30-day body length of male and female mice were compared(n=8). The auditory brainstem response(ABR) was used to detect the auditory threshold and the amplitude of wave I in 9-10-week-old male and female mice(n=5).

Male GLAST^-/- mice had shown significantly lower weight and body length compared to male GLAST^+/+ and GLAST^+/- mice(P＜0.01), and male GLAST^-/- mice showed significant differences compared to GLAST^+/+ from P7 to P30 statistical time. Male GLAST^-/- mice exhibited a significant reduction in weight after P15 compared to male GLAST^+/- mice. In contrast, no significant differences in weight and body length were observed in female GLAST^-/- mice compared with female GLAST^+/+ and GLAST^+/- mice. There was no difference in the hearing threshold detected by ABR between the three genotypes in both male and female mice, but the amplitude of wave I in GLAST^-/- mice was significantly lower than that in male GLAST^+/+ mice(P＜0.01). In contrast, the amplitude of wave I in females was reduced throughout the stimulus intensity but was most significant only at high-intensity stimulation (e.g.80 dB, 90 dB) (P＜0.05).

GLAST knockout affects the normal growth and development of male mice, and decreases the amplitude of wave I, but do not change the threshold, suggesting that GLAST knockout may lead to synaptic pathological changes, and there are gender differences in this effect.