Neuroprotective effect of D-psicose on 6-hydroxydopamine (6-OHDA) induced apoptosis in rat pheochromecytoma (PC12) cells

Purpose: Rare sugars are the class of monosaccharides and their derivatives are rare in nature. There are about 50 kinds of rare sugars and one of them is D-psicose. Recent characterization of physiological function of these sugars revealed a novel inhibitory effect on production of reactive oxygen species (ROS). The ROS leads to oxidative stress causing a cell injury including neuronal cells, inducing cell death via apoptosis. We examined the neuroprotective effects of D-psicose on 6-hydroxydopamine (6-OHDA)-induced apoptosis in PC12 cells, the in vitro model of Parkinson's disease. Material and Methods: Apoptotic characteristics of PC12 cells were assessed by MTT, TUNEL and DNA fragmentation assay. Results: The 50 mM D-psicose exerted significant protective effects against 6-OHDA(200μM)-induced apoptosis, while other sugars such as D-fructose and D-glucose had insignificant or no protective effects. We noticed a significant elevation in intracellular glutathione level at 24 hours after 6-OHDA treatment, while a decrease was noticed at 3 and 6 hours. Especially, exposure with D-psicose and 6-OHDA for 24 hours showed higher intracellular glutathione levels. Conclusions: The increased intracellular glutathione level may well protect the cell from apoptosis by decreasing the oxidative stress and increase cell viability. Our results show that D-psicose may play an important role as a neuroprotective agent for the neurodegenerative diseases. [Jpn J Physiol 54 Suppl:S83 (2004)]