GABA content in the retina of pigmented and albino rats.

Reduction of the melanin precursor DOPA associated with albinism leads to spatiotemporal disturbances in retinal neurogenesis and thus seems to be responsible for numerous neuronal alterations found in albino retinae. To investigate whether these cellular alterations are reflected in retinal neurotransmitter concentrations we compared the levels of GABA and glutamate in the retina of adult pigmented Long Evans and albino Wistar rats using reversed phase-liquid chromatography (RP-HPLC). When normalized to retinal weight, GABA levels showed a statistically insignificant trend to be lower and glutamate values to be higher in albinos than in pigmented animals. The ratio of glutamate to GABA was significantly higher in albino than in pigmented retinae. As numerous studies have shown that the balance between GABA and glutamate plays a crucial role for establishing direction selectivity, these results are discussed in relation to direction selectivity and defects in the optokinetic system of albinos.