Lack of GABAergic modulation of acetylcholine turnover in the rat thalamus.

In order to investigate the GABAergic modulation of the cholinergic midbrain-thalamus pathway, the effects of the GABAA agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) and of the benzodiazepine, diazepam, on acetylcholine (ACh) turnover in the thalamus have been studied. TRACh was also measured in the frontal and parietal cortices of the same animals. Our data confirm an inhibitory GABAergic modulation of the cholinergic nucleus basalis-cortex projection but suggest a lack of GABAergic modulation of the cholinergic midbrain-thalamus pathway.