Effects of dopaminergic cell degeneration on electrophysiological characteristics and GAD65/GAD67 expression in the substantia nigra: different action on GABA cell subpopulations.
The motor disturbances occurring in Parkinson's disease have been partially attributed to a hyperactivity of gamma-aminobutyric acid (GABA)-ergic nigral cells largely in the substantia nigra pars reticulata (SNr) secondary to the degeneration of dopaminergic nigrostriatal neurons. However, some aspects of this response remain unclear. In this work, different electrophysiological and neurochemical parameters were studied in GABAergic cells of the SN after unilateral nigrostriatal dopaminergic lesion using 6-hydroxydopamine injection in rats. Our data showed that 1) the SN under normal conditions contains different subsets of GABAergic cells according to their firing pattern and glutamic acid decarboxylase mRNA levels, and 2) the response of these GABAergic cell subgroups was different after the ipsi- and contralateral dopaminergic cell degeneration. These findings indicate a complex regulation of nigral GABAergic activity after nigrostriatal dopaminergic degeneration that probably involves local mechanisms, the nigro-striato-nigral loop, as well as interhemispheric mechanisms whose anatomical basis remains unstudied.
Díaz
Manuel Rodríguez
MR
Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna, La Laguna, Tenerife, Canary Islands, Spain.
Barroso-Chinea
Pedro
P
Unidad de Investigación del Hospital Universitario de Canarias, La Laguna, Tenerife, Canary Islands, Spain.
Acevedo
Abraham
A
Unidad de Investigación del Hospital Universitario de Canarias, La Laguna, Tenerife, Canary Islands, Spain.
González-Hernández
Tomás
T
Department of Anatomy, Faculty of Medicine, University of La Laguna, La Laguna, Tenerife, Canary Islands, Spain.
D000200:Action Potentials; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004594:Electrophysiology; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009410:Nerve Degeneration / Q000503:physiopathology; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D016627:Oxidopamine; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D007527:Isoenzymes; D012333:RNA, Messenger; D005680:gamma-Aminobutyric Acid; D016627:Oxidopamine; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; C401141:glutamate decarboxylase 2; D004298:Dopamine