The effect of high frequency stimulation (HFS) of the subthalamic nucleus (STN) on the spontaneous activity of substantia nigra pars compacta (SNc) dopaminergic neurons was investigated in normal rats and in rats with globus pallidus (GP) lesions. In normal rats, the spontaneous activity of SNc neurons did not significantly differ from that of rats with GP lesions (4.2 ± 2.2 versus 4.4 ± 2.6 spikes/s). STN-HFS induced an increase of firing rate in the majority of tested cells in normal (76%) and GP-lesioned rats (73%) with an after-effect of 34.4 ± 3.4 and 33.2 ± 3.1 s, respectively. These results demonstrate that STN-HFS influences the activity of the SNc dopaminergic neurons by increasing their firing rate and that this increase of activity is independent of the globus pallidus.
1 Laboratoire de Neurobiologie Preéclinique, INSERM U. 318, CHU-Pavillon B, BP 217, 38043 Grenoble, France
2 Department of Physiology, Jinzhou Medical College, 121002 Jinzhou, Liaoning, PR China
3 Corresponding Author: Abdelhamid Benazzouz
Acknowledgements: This study was supported by Institut National de la Santé et de la Recherche Médicale (INSERM, France), Région Rhône-Alpes (France), Université Joseph Fourier (Grenoble, France).
Received 22 February 2000; accepted 5 March 2000