Table 1. Levels of ceramides, cholesterol, and oxidative stress are increased in neurons exposed to Aβ1–42, and α-tocopherol and an inhibitor of sphingolipid synthesis attenuates these effects of Aβ1–42.

Compound	Control	5 μM Aβ	100 nM ISP-1	100 nM ISP-1 plus 5 μM Aβ	50 ug/ml α-tocopherol	50 ug/ml α-tocopherol plus 5 μM Aβ
SM C18:0	182 ± 21	190 ± 11	143 ± 13	151 ± 20	176 ± 17	196 ± 22
SM C24:0	69.4 ± 7.8	12.6 ± 2.8††	57.5 ± 1.2**	66.5 ± 8.5**	64.3 ± 4.3**	58.2 ± 5.5**
Cer C18:0	20.0 ± 1.4	39.6 ± 2.1††	23.4 ± 4.1*	18.7 ± 1.3**	18.1 ± 4.7**	22.9 ± 4.0*
Cer C24:0	0.95 ± 0.05	2.40 ± 0.21††	1.65 ± 0.20†	0.85 ± 0.13**	0.63 ± 0.09**	0.90 ± 0.10**
Gal-cer C24:0	0.13 ± 0.02	0.20 ± 0.02†	0.11 ± 0.01**	0.13 ± 0.02**	0.11 ± 0.09**	0.15 ± 0.07*
Cholesterol	50.4 ± 14.0	124.1 ± 13.5††	43.9 ± 10.0**	71.7 ± 13.5*	8.6 ± 4.1††**	16.2 ± 5.5††**
Chol-ester C18:1	2.10 ± 0.31	3.30 ± 0.25	1.65 ± 0.29**	0.90 ± 0.03††**	2.33 ± 0.25	2.13 ± 0.51
4HNE	0.19 ± 0.04	1.20 ± 0.28†	0.21 ± 0.07**	0.23 ± 0.06**	0.03 ± 0.02††**	0.06 ± 0.02††**

Cultured hippocampal neurons were pretreated for 24 h with 50 ug/ml α-tocopherol or for 30 min with either 100 nM ISP-1 or vehicle, and were then exposed for 6 h to 5 uM Aβ1-42 or saline (control) and levels of sphingomyelins, ceramides, cholesterols, and HNE were quantified. The values of HNE represent the sum of free, lysine-HNE (2-pentylpyrrole), and histidine-HNE adducts. Values (cps/total phospholipids × 10⁶) are the mean and SE of determinations made in three separate cultures. †, P < 0.05; ††, P < 0.01 compared with the control value. *, P < 0.05; **, P < 0.01 compared with the value for cultures exposed to Aβ alone. SM, sphingomyelin; Cer, ceramide.