Effects of antioxidant pretreatment on the survival of embryonic dopaminergic neurons in vitro and following grafting in an animal model of Parkinson's disease

The effect of pretreating cell suspensions of embryonic rat ventral mesencephala (VM) with antioxidant combinations on the survival of dopaminergic (DA) neurons was studied in vitro and following transplantation into the unilateral 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease. The in vitro experiments examined the effects of two thiol antioxidants, N-acetyl-L-cysteine (NAC) and reduced glutathione (GSH), and a member of the lazaroid family of 21-ammosteroids, U-83836E, singly and in combination, on survival of DA neurons derived from dissociated E14 rat VM tissue. For in vivo studies, cell suspensions were pretreated with combinations of NAC, GSH, and U-83836E prior to transplanting into 6-OHDA-lesioned rats to investigate whether DA neuron survival could be further improved. NAC, GSH, and U-83836E individually increased DA neuron survival in vitro and a combination of all three resulted in the greatest survival. In vivo, pretreatment with U-83836E alone resulted in a significantly greater reduction in amphetamine-induced rotation 6 weeks postgrafting compared with a control group receiving nontreated graft tissue. This functional effect correlated with a significant improvement in DA neuron survival 6 weeks postgrafting. The thiol combination pretreatment of NAC and GSH, and the triple combination of NAC, GSH, and U-83836E, however, failed to improve both functional recovery and DA neuron survival when compared with the nontreated control grafts.