Behavioral and neurochemical effects induced by chronic L-DOPA administration.
L-DOPA, in combination with benserazide, in the ratio 4:1 (w/w), was administered orally to rats. In the staircase maze test a low dose of L-DOPA (3 mg/kg/day) reduced the increase in errors caused by 20 days interruption of daily training, while a higher dose (30 mg/kg/day) was ineffective. A decrease in levels of dopamine in the olfactory system and DOPAC in the striatum was seen at all tested doses of L-DOPA, while an increase in 5-HT levels was seen in the hippocampus and in the striatum. 5-HIAA levels did not change. Levels of ACh in the olfactory system were reduced at all doses of L-DOPA, while in the hippocampus this effect was seen only at the dose of 90 mg/kg/day. The density of muscarinic receptors was not altered. All tested doses of L-DOPA caused norepinephrine levels to fall in the hippocampus and increase in the striatum. The density of alpha 1-adrenoceptors was reduced only at the two lower doses of L-DOPA. A comparison of the neurochemical results with the behavioral modifications seen in the staircase maze test suggests that the catecolaminergic systems are implicated in the memory process.
Molinengo
L
L
Istituto di Farmacologia e Farmacognosia, Universita' di Torino, Italy.
Scordo
I
I
Pastorello
B
B
Orsetti
M
M
Ghi
P
P
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001545:Benserazide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000378:metabolism*; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D051381:Rats; D013997:Time Factors; D014018:Tissue Distribution
D007980:Levodopa; D001545:Benserazide; D000109:Acetylcholine