Reduction in terminal excitability of nigrostriatal dopaminergic neurons in rats following chronic L-dopa administration.
The effects of chronic L-dopa administration on antidromic excitability and the firing rate of nigrostriatal dopaminergic neurons were investigated in urethane-anesthetized rats. Rats that received daily L-dopa (100 mg/kg) and carbidopa (25 mg/kg) for 60 days showed a marked decrease in terminal excitability compared with the controls. There were no significant differences in the firing rates between the two groups. This finding may be related to impaired striatal dopamine release from exogenous L-dopa subsequent to chronic L-dopa treatment.
Third Department of Internal Medicine, Kagawa Medical University, Ikenobe, Japan.
M
M
Tsukaguchi
H
H
Takeuchi
T
T
Touge
K
K
Deguchi
I
I
Sasaki
M
M
Kamoda
M
M
Nishioka
D000818:Animals; D000978:Antiparkinson Agents / Q000494:pharmacology*; D002230:Carbidopa / Q000494:pharmacology*; D002421:Caudate Nucleus / Q000737:chemistry / Q000187:drug effects*; D005071:Evoked Potentials / Q000187:drug effects*; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000978:Antiparkinson Agents; D007980:Levodopa; D002230:Carbidopa