Alkylation of rat dopamine transporters and blockade of dopamine uptake byEEDQ

Effects of the alkylating agent EEDQ (N-ethoxycarbonyl-2-ethoxy-1,2-dihydro quinoline) on levels of dopamine transporter (DA(T)) and function were exam ined in caudate-putamen (CPu) tissue from rat brain. EEDQ produced profound , dose-dependent decreases in DA(T) binding in homogenates (IC50=78 mu M) a nd frozen sections (IC75=200 mu M) that were not reversed by washing. EEDQ also blocked uptake of [H-3]DA in CPu synaptosomes (IC50=17 mu M). However, single (10 mg/kg) or repeated administration of EEDQ in vivo (15 mg/kg/day x3) did not alter DA(T) levels or DA uptake in CPu. Pretreatment of rats wi th alpha-methyl-p-tyrosine and reserpine to deplete endogenous dopamine als o failed to lower DA(T) levels in CPu after injections of EEDQ. EEDQ is an effective alkylating agent for DA(T) in vitro, but not to evaluate metaboli c turnover or function of DA(T) in vivo. The results encourage development of selective and in vivo-active DA(T)-alkylating agents. (C) 2000 Elsevier Science Ltd. All rights reserved.