• BMB Reports
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• v.42 no.8
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• pp.475-481
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• 2009

Emerging data demonstrate pivotal roles for brain insulin resistance and insulin deficiency as mediators of cognitive impairment and neurodegeneration, particularly Alzheimer's disease (AD). Insulin and insulin-like growth factors (IGFs) regulate neuronal survival, energy metabolism, and plasticity, which are required for learning and memory. Hence, endogenous brain-specific impairments in insulin and IGF signaling account for the majority of AD-associated abnormalities. However, a second major mechanism of cognitive impairment has been linked to obesity and Type 2 diabetes (T2DM). Human and experimental animal studies revealed that neurodegeneration associated with peripheral insulin resistance is likely effectuated via a liver-brain axis whereby toxic lipids, including ceramides, cross the blood brain barrier and cause brain insulin resistance, oxidative stress, neuro-inflammation, and cell death. In essence, there are dual mechanisms of brain insulin resistance leading to AD-type neurodegeneration: one mediated by endogenous, CNS factors; and the other, peripheral insulin resistance with excess cytotoxic ceramide production.

• Development and Reproduction
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• v.2 no.1
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• pp.1-8
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• 1998

In mammalian ovary, major portion(>99%) of ovarian follicles undergo atresia. Recent studies have shown that this phenomenon is mediated via GC apoptosis. Ceramide, a product of sphingomyelin hydrolysis, has been proposed as a novel lipid second messenger with specific roles in mediating antiproliferative responses including apoptosis and cell cycle arrest. In the present study, we have examined the effect of ceramide on apoptotic cell death of GC in vitro. GCs were harvested by squeezing the antral follicles from the immature mice (3-4 weeks) and cultured in MEM medium with 10% fetal bovine serum. The cells were treated with various concentrations of ceramide (0 to 50 \mu M)and cultured up to 24 h.Cell death was determined by MTT cell viability assay and apoptosis was examined by acridine orange staining, in situ 3'-end labeling(TUNEL), and flow cytometry. Ceramid treatment induced apoptotic cell death of GC in a time- and a dose-dependent manner. Results of flow cytometric analysis showed that creamide-induced cell death was mostly confined to the $G_{0}$/$G_{1}$ cells. these results provide an evidence for ceramide as a lipid second messenger of apoptosis in mouse GC.