THE TOXIC EFFECT OF ROTENONE ON THE MESENCEPHALIC ASTROCYTES AND DOPAMIN- ERGIC NEURON MICROENVIRONMENT

WEI LIU¹, PENG ZHAO¹, QI LI¹, QIAN WANG², YANCHENG¹, XIAODONG ZHU¹

¹Department of Neurology, Tianjin Medical University General Hospital, Tianjin, 300052, China - ²Department of Neuropathology, Tianjin Neurologic Institute, Tianjin Medical University General Hospital, Tianjin 300052, China, Tianjin Key Laboratory of Injuries, Variations and Regeneration of the Nervous System, Tianjin 300052, China, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin 300052, China

In the present study, we applied the mitochondrial complex I inhibitor rotenone to in vitro cultured astrocytes and examined the changes in lactate dehydrogenase (LDH) activity and the glutathione (GSH) level to determine whether glycolysis was elevat- ed by the resulting dysfunction in oxidative phosphorylation, enhancement of oxygen free radical production and reduction in GSH in the astrocytes. Glial cell line-derived neurotrophic factor (GDNF) has a protective effect on dopaminergic neurons. Western blot was performed to examine whether GDNF expression was altered after rotenone treatment. After short-term expo- sure of astrocytes (11 h) to low dose of rotenone (20, 30, and 40 nM), LDH activity was increased in all rotenone treatment groups compared to the control group and there was significant difference in LDH activity between the rotenone treatment groups and the control group. Additionally, the 40 nM group displayed a decreased GSH level, whereas the other two groups did not significantly differ from the control group. GDNF expression was decreased in all rotenone treatment groups compared to the control group and there was significant difference in GDNF expression between the rotenone treatment groups and the control group and the group treated with 40nM rotenone showed more significant difference than the others.After the dopaminergic neurons were treat- ed with 50μM 6-OHDA and the supernatant of astrocyte treated with different rotenone concentration for 24 hours, the cell viability of the groups treated with different concentration of rotenone has distinguished difference than control group. As the increase of the rotenone’s concentration, the cell viability treated with rotenone decreased. The above results demonstrated that rotenone treatment damaged the astrocytes that constituted the midbrain microenvironment. As a result, the production of oxygen free radi- cals was increased, the GSH and GDNF level was reduced, thus damaging dopaminergic neurons.