High frequency stimulation of the subthalamic nucleus impacts adult neurogenesis in a rat model of Parkinson's disease.

Chronic high frequency stimulation of the subthalamic nucleus (STN-HFS) efficiently alleviates motor symptoms of advanced Parkinson's disease (PD). Here, we looked for possible STN-HFS-induced changes on adult brain neurogenesis in the hippocampus and olfactory bulb that may be related to non-motor deficits associated to PD, such as mood disorders and olfaction deficits. Cell proliferation (Ki-67 immuno-positive-cells) and survival (bromodeoxyuridine (BrdU)-immuno-positive cells) were assessed in the subventricular zone-olfactory bulb continuum and the dentate gyrus of the hippocampus of hemiparkinsonian rats with or without continuous STN-HFS for 8 days. Dopamine lesion impaired cell proliferation and survival through different mechanisms, the effect on proliferation being correlated to the level of dopamine depletion whereas the effect on survival was not. Prolonged STN-HFS did not affect cell proliferation, but increased cell survival bilaterally. In these regions of constitutive neurogenesis, the percentage of new neuroblasts (BrdU-doublecortin-positive cells) was unchanged, suggesting that STN-HFS can lead to a net increase in newly formed neurons later on. STN-HFS also increased new cell survival in the striatum and promoted dopamine system recovery detected by tyrosine hydroxylase immunostaining. These data provide the first evidence that prolonged STN-HFS has a neurorestorative action and support the view that the action of this neurosurgical treatment can bypass the cortico-basal ganglia-thalamocortical loop circuits and largely impinge neuroplasticity and brain function.