Objective      To determine the the expression of γ-aminobutyric acid (GABA) and its synthetic enzyme

glutamic acid decarboxylase 65 (GAD65)

during retinal degeneration.        Methods      Pigmented Royal College of Surgeon rats (RCS-P

+

) and RCS-rd

y

+

-P

+

rats at age of postnatal 15

30

60 and 90 d were selected to study the expression changes of GABA and GAD65 at different time points in retinas by immunofluorescence and western blotting analysis.        Results      GABA and GAD65 were mainly expressed in the inner nuclear layers (INL)

inner plexiform layers (IPL) and ganglion cell layer (GCL). The number of GABA positive cells in RCS-rdy

+

-P

+

rats’ retinas gradually reduced with the age. The number of GABA positive cells in RCS-P

+

was reduced from 15 d to 60 d. However

the number of GABA positive cells was significantly increased after 60 d when compared with RCS-rdy

+

-P

+

rats’ retinas（P0.05）. Furthermore

the expression of GAD65 was constant during the retinal development in RCS-rdy

+

-P

+

rats

and the development did not affect the expression level of GAD65. Compared with the age-matched RCS-rdy

+

-P

+

rats

the expression of GAD65 was increased with the retinal degeneration. The expression of GAD65 was increased at 30 d in RCS-P

+

rats（P0.05）

and its expression was significantly increased at 90 d（P0.01）.        Conclusion      During retinal degeneration

the expression of GABA is consistent with GAD65

and both of their expression is increased significantly. The deprivation of input has little effect on the activity of GABAergic amacrine cells

even higher than that of control retinas.