Figure 6 A photomicrograph of liver tissue sections stained immunohistochemically with caspase-3 antibody. (a) Normal caspase-3 activity. (b) Rats treated with toluene show marked increase of caspase-3 activity when compared with normal reaction in (a). (c) Rats treated with toluene and 150 mg citicoline show that positive caspase-3 activity is still observed. (d) Rats treated with toluene and 300 mg citicoline shows marked decrease in caspase-3 activity in liver tissue (caspase-3 antibody, ×200).