Inhibition ofde novoceramide biosynthesis affects aging phenotype in anin vitromodel of neuronal senescence

Abstract

Although aging is considered to be an unavoidable event, recent experimental evidence suggests that the process can be delayed, counteracted, if not completely interrupted. Aging is the primary risk factor for the onset and development of neurodegenerative conditions like Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. Intracellular calcium (Ca 2+ i) dyshomeostasis, mitochondrial dysfunction, oxidative stress, and lipid dysregulation are critical factors that contribute to senescence-related processes. Ceramides, a class of sphingolipids involved in a wide array of biological functions, are important mediators of cellular senescence, but their role in neuronal aging is still largely unexplored.In this study, we investigated the effects of L-cycloserine (L-CS), an inhibitor of de novo ceramide biosynthesis, on the aging phenotype of cortical neurons that have been maintained in culture for 22 days, a setting employed as an in vitro model of cellular senescence. Our findings indicate that 'aged' neurons display, when compared to control cultures, overt dysregulation of cytosolic and subcellular [Ca 2+ ]i levels, mitochondrial dysfunction, increased reactive oxygen species generation, altered synaptic activity as well as the activation of neuronal death-related molecules. Treatment with L-CS (30 µM) positively affected the senescent phenotype, a result accompanied by recovery of neuronal [Ca 2+ ]i signaling, and reduction of mitochondrial dysfunction and reactive oxygen species generation.The results suggest that the de novo ceramide biosynthesis may represent a critical intermediate in the molecular and functional cascade leading to neuronal senescence. Our findings also identify ceramide biosynthesis inhibitors as promising pharmacological tools to decrease agerelated neuronal dysfunctions. L-CS treatment does not modify NCX activityCeramides can modulate the activity of the plasmalemmal Na + -Ca 2+ exchanger (NCX) 25 , a low capacitance high-affinity system that critically regulates cellular [Ca 2+ ]i. We, therefore, investigated

Inhibition of ceramide accumulation in AdipoR1–/– mice increases photoreceptor survival and improves vision

“…9A). We decided to use a combination of two drugs, desipramine and Lcycloserine (DC), which were previously shown to effectively lower ceramide levels (25) (26)(27)(28)(29)(30). To test if lowering ceramide levels would have a protective effect on photoreceptor cells, two groups of AdipoR1 -/mice (n = 6) were administered either saline or DC by i.p.…”

“…We used a combination of two drugs, desipramine and L-cycloserine (DC), both previously shown to reduce ceramide levels. Lcycloserine is a widely used inhibitor of serine palmitoyl-CoA transferase, the rate-limiting enzyme that catalyzes the first step of ceramide de novo biosynthesis (28,29,59). Desipramine is a functional inhibitor of acidic sphingomyelinase (ASMase) which produces ceramide through hydrolysis of sphingomyelin (25,27,30,39).…”