Silencing urokinase in the ventral tegmental area in vivo induces changes in cocaine-induced hyperlocomotion.
Serine proteases in the nervous system have functional roles in neural plasticity. Among them, urokinase-type plasminogen activator (uPA) exerts a variety of functions during development, and is involved in learning and memory. Furthermore, psychostimulants strongly induce uPA expression in the mesolimbic dopaminergic pathway. In this study, doxycycline-regulatable lentiviruses expressing either uPA, a dominant-negative form of uPA, or non-regulatable lentiviruses expressing small interfering RNAs (siRNAs) targeted against uPA have been prepared and injected into the ventral tegmental area (VTA) of rat brains. Over-expression of uPA in the VTA induces doxycycline-dependent expression of its receptor, uPAR, but not its inhibitor, plasminogen activator inhibitor-1 (PAI-1). uPAR expression in the VTA is repressed upon silencing of uPA with lentiviruses expressing siRNAs. In addition, over-expression of uPA in the VTA promotes a 15-fold increase in locomotion activity upon cocaine delivery. Animals expressing the dominant-negative form of uPA did not display such hyperlocomotor activity. These cocaine-induced behavioural changes, associated with uPA expression, could be suppressed in the presence of doxycycline or uPA-specific siRNAs expressing lentiviruses. These data strongly support the major role of urokinase in cocaine-mediated plasticity changes.
Bahi
Amine
A
Institute of Biochemistry, University of Fribourg, Fribourg, Switzerland.
Boyer
Frederic
F
Kafri
Tal
T
Dreyer
Jean-Luc
JL
D000818:Animals; D001522:Behavior, Animal; D015152:Blotting, Northern / Q000379:methods; D002460:Cell Line; D003042:Cocaine / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004318:Doxycycline / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005822:Genetic Vectors / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D016086:Lentivirus / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects*; D016296:Mutagenesis / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014162:Transfection / Q000379:methods; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism*; D017557:Ventral Tegmental Area / Q000187:drug effects*
D018765:Dopamine Uptake Inhibitors; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins; D014568:Urokinase-Type Plasminogen Activator; D003042:Cocaine; D004318:Doxycycline