Role of striatum in the pause and burst generation in the globus pallidus of 6-OHDA treated rats

Frontiers in Systems Neuroscience

Hitoshi eKita¹  Takako eKita¹ 

[1] The University of Tennessee Health Science Center;

关键词: Basal Ganglia;    Globus Pallidus;    Striatum;    firing pattern;    burst firing;    Dopamine depletion;   

DOI  :  10.3389/fnsys.2011.00042

来源: DOAJ

【 摘 要 】

Electrophysiological studies in patients and animal models of Parkinson’s disease (PD) often reported increased burst activity of neurons in the basal ganglia. Neurons in the globus pallidus external segment (GPe) in 6-hydroxdopamine (6-OHDA)-treated hemi-parkinsonian rats fire with strong burst interrupted by pauses. This study was to evaluate a hypothesis that DA depletion increases burst firings of striatal (Str) neurons projecting to the GPe and that the increased Str-GPe burst inputs play a significant role in the generation of pauses and bursts in GPe and its projection sites. To evaluate this hypothesis, unitary activity of Str and GPe was recorded from control and 6-OHDA-treated rats anesthetized with 0.5-1% isoflurane. The occurrence of pauses and bursts in the firings of GPe neurons was significantly higher in 6-OHDA than in normal rats. Muscimol injection into the Str of 6-OHDA rats increased the firing rate and greatly reduced the pauses and bursts in GPe. Recording from Str revealed that most of the presumed projection neurons in control rats have very low spontaneous activity and only occasional neurons exhibited spontaneous burst firings with an average rate of less than 2Hz. In DA-depleted Str, neurons having stronger bursts and higher average firing rate were more frequently encountered. Juxtacellular labeling revealed that most of these neurons were medium spiny neurons projecting only to GPe. Injection of a behaviorally effective dose of methyl-L-DOPA into the Str of 6-OHDA rats significantly increased the firing rate and decreased number of pauses of GPe neurons. These data validate the hypothesis that DA depletion increases burst firings of Str neurons projecting to the GPe and that the increased Str-GPe burst inputs play a significant role in the generation of pauses and bursts in GPe. These results suggest that treatment to reduce burst Str-GPe inhibitory inputs may help to restore some of the PD disabilities.

【 授权许可】

Unknown