Objective      To investigate the contributions of glutamate metabolism to electroretinogram (ERG) b-wave in time and frequency domains by wavelet transform in a glutamine synthetase (GS) inhibited rat model.       Methods      Different concentrations of glutamine synthetase inhibitor (DL-AAA) were subretinally injected into the right eyes of Rcs-rdy

+

-p

+

rats

and phosphate buffer solution was subretinally delivered into the left eyes as control. Dark-adapted ERG of

all the rats was recorded with an RETI-scan system. A gold-foil ring cornea electrode was used as the recording electrode and a home-made stainless steel needle electrode was used as the reference electrode. The intensity of light ranged from -40 dB to 5 dB. Data were collected and analyzed with software Matlab7.0

and students’ t test was used for statistical analysis.       Results      The characteristics of time domain as follows: with the increase of DL-AAA concentration

the amplitudes of a-wave and b-wave were decreased. In the low concentration group

no any significant change was observed. However

the amplitudes had significant changes in the middle and high concentration groups as compared with the control group (P0.05

P0.01). Moreover

in the high concentration group

the parameters (b/a and T1/2d) were changed dramatically. The characteristics of frequency domain as follows: when the envelope threshold was set at 0.8

with the increase of DL-AAA concentration

the minimum ratio of circle increased and the dispersion increased (P0.05). Meanwhile

the time of peak delayed (P0.05).       Conclusion      The glutamate metabolism in the retina is disrupted after inhibiting GS in Müller cells

and this change contributes to the earlier part of ERG b-wave in the time domain and the slower part in the frequency domain

indicating that Müller cells play a major role in the stability of the retinal function.