Effect of microiontophoretic application of dopamine on subthalamic nucleus neuronal activity in normal rats and in rats with unilateral lesion of the nigrostriatal pathway
European Journal of Neuroscience. 2001-07-01; 14(2): 373-381
DOI: 10.1046/j.0953-816X.2001.01644.x
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1. Eur J Neurosci. 2001 Jul;14(2):373-81. doi: 10.1046/j.0953-816x.2001.01644.x.
Effect of microiontophoretic application of dopamine on subthalamic nucleus
neuronal activity in normal rats and in rats with unilateral lesion of the
nigrostriatal pathway.
Ni Z(1), Gao D, Bouali-Benazzouz R, Benabid AL, Benazzouz A.
Author information:
(1)Laboratoire de Neurosciences Précliniques, INSERM U.318, CHU, Pavillon B,
B.P. 217, 38043 Grenoble Cedex 09, France.
The subthalamic nucleus (STN) receives dopamine inputs from the substantia nigra
but their implication in the pathophysiology of parkinsonism is still debated.
Extracellular microrecordings were used to study the effect of
microiontophoretic injection of dopamine and the D1 receptor agonist SKF 38393
on the activity of STN neurons in normal and 6-hydroxydopamine-lesioned rats
under urethane anaesthesia. Dopamine and SKF induced an increase in the firing
rate of the majority of STN neurons in both normal and 6-OHDA rats. In rats with
6-OHDA lesions, the percentage of firing rate increase did not differ from that
of controls. When GABA, glutamate and dopamine were all applied to the same
individual STN neurons, GABA induced an inhibitory effect and glutamate and
dopamine caused an excitatory effect in both groups. This excitatory response
was suppressed by the application of GABA. Systemic administration of
apomorphine provoked a decrease in the firing rate of STN neurons in rats with
6-OHDA lesions. These results show that dopamine exerts an excitatory influence
on STN neurons, suggesting that the inhibitory effect induced by the systemic
injection of apomorphine is due to the GABAergic inputs from the globus pallidus
as predicted by the current model of basal ganglia organization. In addition, we
show that dopamine, GABA and glutamate can act on the same STN neuron and that
GABA can reverse the excitatory effect of dopamine and glutamate, suggesting the
predominant influence of GABAergic inputs to the subthalamic nucleus.
DOI: 10.1046/j.0953-816x.2001.01644.x
PMID: 11553287 [Indexed for MEDLINE]