The expression of VIP exists on photoreceptor- outer segment, inner nuclear layer and inner plexiform layer of retina and choroids, and weak expression exists on ganglion cell and nerve fiber layer.

In the retina of RCS rats, GABA-like immunoreactivity was observed in the inner plexiform layer, few GABA-ergic amacrine cells and the ganglion cell layer.

The cerebral cortex include three layers: outer plexiform layer, cell layer and inner plexiform layer. There are some small cells scatter in outer and inner plexiform layer.