Silencing dopamine D3-receptors in the nucleus accumbens shell in vivo induces changes in cocaine-induced hyperlocomotion.
The dopamine D(3) receptor (D(3)R) is an important pharmacotherapeutic target for its potential role in psychiatric disorders and drug dependence. To further explore its function in rats, a regulatable lentivirus, Lenti-D3, holding the rat D(3)R cDNA, has been constructed as well as three nonregulatable lentiviruses, Lenti-D3-siRNA1, Lenti-D3-siRNA2 and Lenti-D3-siRNA3, expressing small hairpin RNAs, aimed at silencing D(3)R expression and specifically targeted against different regions of the D(3)R mRNA. In vitro, Lenti-D3 expressed D(3)R and could efficiently be blocked with Lenti-D3-Sils. These viruses were stereotaxically injected into the shell part of the nucleus accumbens (NAcc) and effects of passive cocaine delivery on locomotor activity were assessed. Manipulations of D(3)R levels induced changes in the locomotor stimulant effects of cocaine as compared to control treatment. Suppression of dopamine (DA) D(3)R in the NAcc by means of local knockdown (with Lenti-D3-Sils) increased locomotor stimulant effects, whereas its overexpression with Lenti-D3 drastically reduced them. The latter effects could be reversed when animals were fed doxycycline, which prevented lentiviral-mediated DA D(3)R overexpression in the NAcc. Gene expression assessed by quantitative RT-PCR confirmed very efficient gene knockdown in vivo in animals treated with Lenti-D3-Sils (> 93% silencing of D(3)R gene). Thus D(3)R expression significantly contributes to behavioural changes associated with chronic cocaine delivery.
Bahi
Amine
A
Institute of Biochemistry, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.
Boyer
Frederic
F
Bussard
Gaelle
G
Dreyer
Jean-Luc
JL
D000818:Animals; D001522:Behavior, Animal; D015152:Blotting, Northern / Q000379:methods; D002460:Cell Line; D019970:Cocaine-Related Disorders / Q000503:physiopathology* / Q000628:therapy; D004318:Doxycycline / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D020868:Gene Silencing / Q000187:drug effects / Q000502:physiology*; D005822:Genetic Vectors / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism / Q000502:physiology*; D050637:Receptors, Dopamine D3; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014162:Transfection / Q000379:methods
C493593:DRD3 protein, human; C493595:Drd3 protein, rat; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C113776:dopamine D2L receptor; D004318:Doxycycline