Fig. 1

Apoptosis in primary rat neurons incubated with UCB, and Aβ peptide. Isolated neurons were cultured for 8 days prior to incubation with either 86 µM unconjugated bilirubin (UCB), 25 µM amyloid-β (Aβ) peptide (25–35), a combination of toxic agent plus 100 µM ursodeoxycholate (UDC), or no addition (control). Cells were fixed, and then assayed for nucleotide-labeled genomic DNA as described in “Materials and Methods.” (A) TUNEL-positive neurons (dark stain) in cells incubated with no addition (a; control), UCB (b), Aβ peptide (c), UDC (d), UCB plus UDC (e), and Aβ peptide plus UDC (f). (B) Percentage of TUNEL-positive neurons. Values are means ± standard error of the mean (SEM) of at least three separate experiments. *p < 0.01 from control; †p < 0.05 from toxic stimuli alone.