The sphingolipid ceramide exerts a pro-apoptotic role in variety of cellular and organ systems and increased of de-novo synthesis of ceramide are associated with initiation of cell death. In Retinitis Pigmentosa (RP) photoreceptor death occurs by apoptosis but the individual pathways of this process are unknown. We employed an animal model of RP, the rd10 mutant mouse, to assess the role of ceramide in inherited photoreceptor degeneration. We used Myriocin, a known inhibitor of serine palmitoyltransferase (SPT, the rate-limiting enzyme of ceramide biosynthesis) which was either...