Geranylgeranylacetone Suppresses N-Methyl-N-nitrosourea-Induced Photoreceptor Cell Loss in Mice.

Retinitis pigmentosa is a disease characterized by the loss of photoreceptor cells. The N-methyl-N-nitrosourea (MNU)-induced retinal degeneration model is widely used to study the mechanism of these retinal degenerative disorders because of its selective photoreceptor cell death. As for the cell death mechanism of MNU, calcium-calpain activation and lipid peroxidation processes are involved in the initiation of this cell death. Although such molecular mechanisms of the MNU-induced cell death have been described, the total image of the cell death is still obscure. Heat shock protein 70 (HSP70) has been shown to function as a chaperon molecule to protect cells against environmental and physiological stresses. In this study, we investigated the effect of geranylgeranylacetone (GGA), an accylic polyisoprenoid, on MNU-induced photoreceptor cell loss. HSP70 induction by GGA was effective against MNU-induced photoreceptor cell loss as a result of its ability to prevent HSP70 degradation. The data indicate that GGA may help to suppress the onset and progression of retinitis pigmentosa.