D1 and D2 dopamine receptor agonists improve deficits in motor programming of cats with a 6-hydroxydopamine lesion in the A8 cell group

Recently, it has been shown that a small 6-hydroxydopamine lesion in the A8 cell group of cats trained to walk on a treadmill produces long-lasting deficits (Arts and Cools, 1998, Behav. Neurosci. 112; pp. 102-105). Some deficits could be attributed to a hypofunction of A9 cells, that is a reduced ability to switch arbitrarily motor patterns, and other deficits to a hyperfunction of A10 cells, that is an improved ability to switch motor patterns with the help of cues. This experiment was repeated in this study and the elicited behavioural symptoms were systemically treated with the dopamine D1 receptor agonist SKF 81297 and dopamine D2 receptor agonist LY 171555. The results show that a cocktail of these agonists restored both the lesion-induced reduced ability to switch arbitrarily motor patterns and the lesion-induced increased ability to switch motor patterns with the help of cues, suggesting that this treatment restored the functional misbalance between the A9 and A10 cells. (C) 2000 Elsevier Science B.V. All rights reserved.