PHOSPHOLIPASE-C BETA-4 IS INVOLVED IN MODULATING THE VISUAL RESPONSE IN MICE

Expression of G protein-regulated phospholipase C (PLC) beta 4 in the retina, lateral geniculate nucleus, and superior colliculus implies th at PLC beta 4 may play a role in the mammalian visual process, A mouse line that lacks PLC beta 4 was generated and the physiological signif icance of PLC beta 4 in murine visual function was investigated, Behav ioral tests using a shuttle bos demonstrated that the mice lacking PLC beta 4 were impaired in their visual processing abilities, whereas th ey showed no deficit in their auditory abilities, In addition, the PLC beta 4-null mice showed 4-fold reduction in the maximal amplitude of the rod a- and b-wave components of their electroretinograms relative to their littermate controls, However, recording from single rod photo receptors did not reveal an significant differences between the PLC be ta 4-null and wild-type littermates, nor were there any apparent diffe rences in retinas examined with light microscopy. While the behavioral and electroretinographic results indicate that PLC beta 4 plays a sig nificant role in mammalian visual signal processing, isolated rod reco rding shows little or no apparent deficit, suggesting that the effect of PLC beta 4 deficiency an the rod signaling pathway occurs at some s tage after the initial phototransduction cascade and may require cell- cell interactions between rods and other retinal cells.