Reduction of apomorphine-induced rotational behaviour by subthalamic lesion in 6-OHDA lesioned rats is associated with a normalization of firing rate and discharge pattern of pars reticulata neurons
Exp Brain Res. 1995-07-01; 105(1):
DOI: 10.1007/BF00242181
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1. Exp Brain Res. 1995;105(1):48-58. doi: 10.1007/BF00242181.
Reduction of apomorphine-induced rotational behaviour by subthalamic lesion in
6-OHDA lesioned rats is associated with a normalization of firing rate and
discharge pattern of pars reticulata neurons.
Burbaud P(1), Gross C, Benazzouz A, Coussemacq M, Bioulac B.
Author information:
(1)Laboratoire de Neurophysiologie URA CNRS 1200, Université de Bordeaux II,
France.
The effect of subthalamic nucleus (STh) lesion on apomorphine-induced rotational
behaviour and unit activity of substantia nigra pars reticulata (SNr) neurons
was studied in normal, sham-control and unilateral 6-OHDA-lesioned rats [SN pars
compacta (SNc)-lesioned]. In the latter, contraversive rotational behaviour was
greatly reduced by an additional ipsilateral STh lesion. A moderate ipsiversive
rotation was observed in rats with a single STh lesion. Concurrently, SN unit
extracellular recordings were performed in age-matched normal rats,
sham-controls for both lesions, STh-lesioned rats, SNc-lesioned rats, and
SNc-lesioned rats with an ipsilateral STh lesion (SNc+STh-lesioned). Pars
reticulata neurons had a higher mean firing rate in SNc-lesioned rats than in
control rats. Furthermore, 68% of SNr neurons in SNc-lesioned rats had a tonic
discharge pattern (against 92.3% in control rats) and 32% a mixed or bursting
pattern. After STh lesion, a clear decrease in SNr firing rate was observed in
SNc-lesioned rats. Moreover, STh lesion improved interspike interval regularity
and decreased the occurrence of bursting patterns. In rats with a single STh
lesion, the firing rate was no different from that of the sham-controls but the
discharge pattern was more regular. These data show that STh lesion decreased
apomorphine-induced rotational behaviour in dopamine-depleted animals. This
effect could be related to the suppression of the excitatory effect of STh
efferents on the SNr neurons. STh lesion both counterbalanced the increased
activity of SNr neurons and regularized their discharge pattern.
DOI: 10.1007/BF00242181
PMID: 7589317 [Indexed for MEDLINE]