Ethanol-induced changes in the content of triglycerides, ceramides, and glucosylceramides in cultured neurons.

Abstract

BACKGROUND:

Ethanol induces apoptosis in cultured neurons. To assess the involvement of sphingolipids and neutral lipids in the apoptotic process, ethanol-induced alterations in lipid content and metabolism were examined by using primary cultured rat cerebellar granule neurons (CGNs), human neuroblastoma SK-N-SH cells, and mouse neuroblastoma Neuro2a cells. Ethanol treatment conditions that induced apoptosis in CGNs and SK-N-SH cells but not in Neuro2a cells were used for these experiments.

METHODS:

Cultured neurons were treated with and without 100 mM ethanol for one to three days, and the amounts of cellular sphingolipids [ceramide, glucosylceramide (GlcCer), and sphingomyelin] and neutral lipids [cholesterol, triglyceride (TG), and cholesterol ester (ChE)] were analyzed by high-performance thin-layer chromatography, using a Coomassie brilliant blue staining method. The incorporation of [C] acetate into each lipid fraction was measured in CGNs treated with and without ethanol. Also, the effect of delipidated serum, sterols, myriocin (a serine-palmitoyltransferase inhibitor), and desipramine (an acid sphingomyelinase inhibitor) on ethanol-induced lipid changes was studied by using Neuro2a cells.

RESULTS:

The most prominent change common to CGN, SK-N-SH, and Neuro2a cells was ethanol-induced TG accumulation. Higher incorporation of radioactivity into TG was also observed in ethanol-treated cultures when cellular lipids were metabolically labeled with [C] acetate in CGNs. In addition, ethanol elevated ceramide levels in all these neurons. However, ethanol induced decreases in GlcCer along with the reduction of cell viability in SK-N-SH cells and CGNs, whereas it increased GlcCer in Neuro2a cells that remained viable. Myriocin, which reduced ceramide levels, attenuated ethanol-induced cell death in SK-N-SH cells. Ethanol-induced accumulation of TG was sterol-independent, whereas changes in ceramide and GlcCer were affected in Neuro2a cells by the presence of sterols in the medium. Staurosporine, which induced cell death in SK-N-SH cells, increased levels of TG, ChE, and ceramides and reduced the level of GlcCer.

CONCLUSIONS:

The results showing that ethanol induces accumulation of TG and ceramide in cultured neurons suggest that ethanol enhances lipogenesis and/or reduces fatty acid degradation in neurons, as previously observed in other cell types. Further, ethanol-induced changes in lipid metabolism, specifically those of ceramide and GlcCer, may be related to the ethanol-induced apoptotic pathway.

• Authors: Mariko Saito, Mitsuo Saito, Thomas B Cooper, Csaba Vadasz
• Journal: Alcoholism, clinical and experimental research (Alcohol Clin Exp Res) Vol. 29 Issue 8 Pg. 1374-83 (Aug 2005) ISSN: 0145-6008 [Print] England
• PMID: 16131844 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Ceramides
• Enzyme Inhibitors
• Fatty Acids, Monounsaturated
• Glucosylceramides
• Triglycerides
• Ethanol
• Serine C-Palmitoyltransferase
• Sphingomyelin Phosphodiesterase
• Desipramine
• thermozymocidin

Topics

• Animals
• Apoptosis (drug effects)
• Cell Line, Tumor
• Cells, Cultured
• Ceramides (metabolism)
• Cerebellum (cytology, drug effects)
• Desipramine (pharmacology)
• Enzyme Inhibitors (pharmacology)
• Ethanol (toxicity)
• Fatty Acids, Monounsaturated (pharmacology)
• Glucosylceramides (metabolism)
• Humans
• Mice
• Neuroblastoma
• Neurons (drug effects, metabolism)
• Rats
• Rats, Sprague-Dawley
• Serine C-Palmitoyltransferase (antagonists & inhibitors, physiology)
• Sphingomyelin Phosphodiesterase (antagonists & inhibitors, physiology)
• Triglycerides (metabolism)