Electrophysiological changes in substantia nigra after striatal infarction.
The GABAergic efferent pathway from the striatum exerts inhibitory control on the substantia nigra pars reticulata (SNR) neurones. We studied sequential changes in spontaneous single-unit activities in the ipsilateral SNR 1 h, 1 day, 7 days and 14 days after striatal infarction induced by middle cerebral artery occlusion (MCAO) in rats. Compared with a sham-operated group, there was no change in the firing rate 1 h after MCAO, and one day after MCAO the mean firing rate decreased. The firing rate of SNR neurones at 7 and 14 days after MCAO was significantly reduced compared with the sham-operated group. Only two neurones (sham-operated group and 1 h after MCAO group) fired with high frequency. Histological examination revealed degeneration of the ipsilateral SNR 7 and 14 days after MCAO. Our results indicated that SNR neuronal degeneration accompanied by striatal ischaemia does not simply depend on hyperexcitation due to the activation of a disinhibition mechanism.
Asai
T
T
Department of Neurosurgery, Kinki University, Osaka Japan.
Kataoka
K
K
Tokuno
T
T
Chichibu
S
S
Taneda
M
M
D000818:Animals; D002544:Cerebral Infarction / Q000473:pathology / Q000503:physiopathology*; D003250:Constriction; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013378:Substantia Nigra / Q000098:blood supply / Q000166:cytology / Q000503:physiopathology*