Opiates and enkephalins inhibit synthesis of gangliosides and membrane glycoproteins in mouse neuroblastoma cell line N4TG1.

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Abstract
When mouse neuroblastoma clonal cell line N4TGI cells were cultured in the presence of opiates or enkephalins, in the range 10-6-10-10 M for 24 h, a dose-dependent inhibition of the incorporation of [3H]glucosamine and [14C]-g-lactose into sialoglycosphingolipids and glycoproteins was observed. The gangliosides most affected comigrated in TLC systems with Gm2 (GalNAc[AcNeu]Gal-Glc-ceramide), GM1 (Gal-GalNAc[AcNeu]Gal-Glc-ceramide) and GD1a (AcNeu-Gal-GalNAc[AcNeu]Gal-Glc-ceramide). The effects were sterospecific and naloxone-reversible. Polyacrylamide gel electrophoresis revealed that the synthesis of a large number of membrane glycoproteins was stereospecifically inhibited. Synthesis of other proteins and glycoproteins, proteoglycans, DNA and membrane phospholipids and the rate of cell division were not altered in any specific or stereospecific manner. Clonal cell lines (neuroblastomas and oligodendroglioma) and human skin fibroblasts, which do not possess opiate receptors, did not respond to opiates or enkephalins in a stereospecific manner.