The intrastriatal infusion of relatively low doses of quinolinic acid (Quin, 4-10 nmol/h) for 1 or 2 weeks induced time-dependent degeneration of neuronal cells. We examined the effects of these infusions on discrete cellular populations. The distribution of somatostatin (SOM)-positive neurons labelled by immunocytochemistry or by NADPH-diaphorase histochemistry and of cholinergic cells stained by acetylcholinesterase was quantified in the peripheral portion of the lesioned area. SOM-positive cells did not appear selectively spared by Quin infusion. The proportion of SOM- and NADPH-diaphorase-positive neurons killed by exposure to Quin was similar to or higher than the percentage of total neurons degenerated (from 30 to 85%). A selective sparing of cholinergic cells was observed in all conditions examined; perfusion of 6 nmol/h for a week induced 65% of cell death while not more than 30% of cholinergic neurons were killed. Thus, the neurochemical similarity between the degenerative effects of intrastriatal Quin and Huntington's disease (HD) did not appear confirmed by the chronic perfusion of low doses of Quin for SOM-positive neurons, whereas an analogy between Quin's effects and HD was suggested by the pattern of AChE staining.