title: U18666A inhibits intracellular cholesterol transport and neurotransmitter release in human neuroblastoma cells.
abstract: To determine if neurochemical function might be impaired in cell models with altered cholesterol balance, we studied the effects of U18666A (3-beta-[(2-diethyl-amino)ethoxy]androst-5-en-17-one) on intracellular cholesterol metabolism in three human neuroblastoma cell lines (SK-N-SH, SK-N-MC, and SH-SY5Y). U18666A (< or =0.2 microg/ml) completely inhibited low density lipoprotein (LDL)-stimulated cholesterol esterification in SK-N-SH cells, while cholesterol esterification stimulated by 25-hydroxycholesterol or bacterial sphingomyelinase was unaffected or partially inhibited, respectively. U18666A also blocked LDL-stimulated downregulation of LDL receptor and caused lysosomal accumulation of cholesterol as measured by filipin staining. U18666A treatment for 18 h resulted in 70% inhibition of K+-evoked norepinephrine release in phorbol ester-differentiated SH-SY5Y cells, while release stimulated by the calcium ionophore A23187 was only slightly affected. These results suggest that U 18666A may preferentially block a voltage-regulated Ca2+ channel involved in norepinephrine release and that alterations in neurotransmitter secretion might be a feature of disorders such as Niemann-Pick Type C, in which intracellular cholesterol transport and distribution are impaired.
authors.affiliation: Atlantic Research Centre, Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: S M
authors.initials: SM
authors.lastname: Sparrow
authors.forename: J M
authors.initials: JM
authors.lastname: Carter
authors.forename: N D
authors.initials: ND
authors.lastname: Ridgway
authors.forename: H W
authors.initials: HW
authors.lastname: Cook
authors.forename: D M
authors.initials: DM
authors.lastname: Byers
mesh_terms: D000736:Androstenes / Q000494:pharmacology*; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism*; D003470:Culture Media; D015536:Down-Regulation; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology; D007700:Kinetics; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011973:Receptors, LDL / Q000187:drug effects / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000201:enzymology; D014407:Tumor Cells, Cultured