In the rat striatum, acetylcholine (ACh) increases dopamine (DA) release. The role of increased cholinergic activity provoked by acetylcholinesterase inhibitors (AChEi) on DA release is currently under revision after recent papers have shown a blockade of nicotinic transmission by AChEi in vitro. To study the effects of AChEi in vivo, Fasciculin2 (FAS), a peptidergic AChEi, and physostigmine (PHY), a classical carbamate AChEi, were applied through push-pull or microdialysis cannulae respectively, to the striatum of rats, alone or with ACh. Extracellular concentrations of DA were assessed by HPLC with electrochemical detection.