6-HYDROXYDOPAMINE LESIONS REDUCE BDNF MESSENGER-RNA LEVELS IN ADULT-RAT BRAIN SUBSTANTIA-NIGRA

EXFRESSION of brain-derived neurotrophic factor (BDNF) in the ventral mesencephalon has been assayed by mRNA in situ hybridization in adult rats with unilateral injections of 6-hydroxydopamine in the substantia nigra. On contralateral control sides, a specific hybridization signa l was detected in the substantia nigra pars compacta (A9), ventral teg mental area (A10) and substantia nigra pars lateralis (A8). Cellular l evels of BDNF mRNA were lower than those in BDNF expressing cortical a nd hippocampal neurons. The 6-hydroxydopamine injections completely ab olished BDNF mRNA labeling in the pars compacta of the substantia nigr a, whereas many labeled neurons remained in the ventral tegmental area and pars lateralis. The results strongly suggest that BDNF is express ed by nigral dopaminergic neurons.