Time-course of changes in firing rates and firing patterns of subthalamic nucleus neuronal activity after 6-OHDA-induced dopamine depletion in rats

Brain Res. 2001 Apr 27;899(1-2):142-7. doi: 10.1016/s0006-8993(01)02219-3.

Abstract

The subthalamic nucleus (STN) plays a key role in motor control. Disorganization of its neuronal activity is implicated in the manifestation of parkinsonian motor symptoms. The aim of the present work was to study the time-course of changes in the firing activity of STN neurons in a rat model of parkinsonism. Electrophysiological recordings were done in normal rats and four groups of rats at different time points after 6-hydroxydopamine (6-OHDA) microinjection into the pars compacta of substantia nigra (SNc). Results showed a significant decrease in firing rate during the first and second weeks post lesion (5.53+/-0.56 and 7.66+/-0.73 spikes/s, respectively) compared to normal rats (11.13+/-0.59 spikes/s). From the 3rd week after 6-OHDA injection the firing rates returned toward baseline, with an average of 9.71+/-0.51 spikes/s during the 3rd week and 11.13+/-0.71 spikes/s during the 4th week. With regard to firing pattern, the majority of STN cells (90%) discharged regularly or slightly irregularly in normal animals. Only 4% exhibited burst activity and 6% had mixed firing patterns. After SNc-lesion, the percentage of cells exhibiting burst and mixed patterns increased progressively from 35% during the first week to 56% at week 4 post-lesion. In sum, these experiments revealed that the firing rate of STN neurons was altered only transiently following nigral lesions, whereas a progressive and stable change in the firing pattern was observed up to 4 weeks post lesion, suggesting that the persistence of bursts firing more closely relates to the motor pathologies of this rat model of parkinsonism.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Adrenergic Agents / toxicity
  • Animals
  • Dopamine / metabolism*
  • Male
  • Neurons / drug effects*
  • Neurons / physiology
  • Oxidopamine / toxicity*
  • Parkinsonian Disorders / chemically induced*
  • Parkinsonian Disorders / metabolism
  • Rats
  • Rats, Wistar
  • Subthalamic Nucleus / drug effects*
  • Subthalamic Nucleus / physiology
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology
  • Time Factors

Substances

  • Adrenergic Agents
  • Oxidopamine
  • Dopamine