Figure 9.

Astrocyte IL-1RI signaling is required for the mediation of IL-1β-induced hypoxic neuronal injury. Chimeric mixed cortical cell cultures were obtained by plating wild-type (IL-1RI^+/+) or IL-1RI-deficient (IL-1RI^−/−) neurons on either wild-type (IL-1RI^+/+) or IL-1RI-null mutant (IL-1RI^−/−) astrocytes These cultures were treated with 1 ng/ml IL-1β for 20–24 h (black bars) or vehicle (hatched bars), washed, and then deprived of oxygen. A, The percentage of total neuronal cell death was determined 20–24 h later as described in Materials and Methods (n = 18–24 cultures pooled from 4 different experiments). B, After 60 min, cells were washed with HBSS, and ¹⁴C-l-cystine was added for 5 min as described in Materials and Methods. Data are expressed as ¹⁴C-l-cystine uptake in picomoles per minute per milligram protein (n = 6–12 cultures pooled from 2–4 different experiments). C, After 120 min of hypoxia, supernatant was collected to measure accumulation of glutamate in the bathing medium via HPLC. Data are expressed as the mean ± SEM glutamate accumulation in micromolar (n = 6 cultures pooled from 3 different experiments). An asterisk indicates a value significantly greater than oxygen deprivation alone (−IL-1β), as determined by two-way ANOVA followed by a Bonferroni's t test for multiple comparisons. Significance was assessed at p < 0.05.