In vivo reduction of striatal D1R by RNA interference alters expression of D1R signaling-related proteins and enhances methamphetamine addiction in male rats

• Published in: Brain Structure and Function 2020-04, Vol.225 (3), p.1073-1088
• Main Authors: Kreisler, Alison D., Terranova, Michael J., Somkuwar, Sucharita S., Purohit, Dvijen C., Wang, Shanshan, Head, Brian P., Mandyam, Chitra D.
• Format: Article
• Language: English
• Subjects: Addictions; Amphetamine-Related Disorders - metabolism; Animals; Biomedical and Life Sciences; Biomedicine; Caudate-putamen; Caveolin; Caveolin-1; Cell Biology; Conditioning, Operant - drug effects; Conditioning, Operant - physiology; Corpus Striatum - drug effects; Corpus Striatum - metabolism; Dopamine; Dopamine D1 receptors; Dopamine Plasma Membrane Transport Proteins - metabolism; Dopamine transporter; Drug-Seeking Behavior - drug effects; Drug-Seeking Behavior - physiology; Gene Knockdown Techniques; Localization; Male; MAP kinase; Membrane proteins; Methamphetamine; Methamphetamine - administration & dosage; Neostriatum; Neurology; Neurosciences; Original Article; Phenotypes; Postsynaptic density proteins; Proteins; Rats, Long-Evans; Receptors, Dopamine D1 - metabolism; Receptors, Dopamine D2 - metabolism; RNA, Small Interfering - administration & dosage; RNA-mediated interference; Rodents; Self-administration; Sucrose; Western blotting
• ISSN: 1863-2653; 1863-2661; 0340-2061
• DOI: 10.1007/s00429-020-02059-w

This study sought to determine if reducing dopamine D1 receptor (D1R) expression in the dorsal striatum (DS) via RNA-interference alters methamphetamine self-administration. A lentiviral construct containing a short hairpin RNA (shRNA) was used to knock down D1R expression (D1RshRNA). D1RshRNA in male rats increased responding for methamphetamine (i.v.) under a fixed-ratio schedule in an extended access paradigm, compared to D1R-intact rats. D1RshRNA also produced a vertical shift in a dose–response paradigm and enhanced responding for methamphetamine in a progressive-ratio schedule, generating a drug-vulnerable phenotype. D1RshRNA did not alter responding for sucrose (oral) under a fixed-ratio schedule compared to D1R-intact rats. Western blotting confirmed reduced D1R expression in methamphetamine and sucrose D1RshRNA rats. D1RshRNA reduced the expression of PSD-95 and MAPK-1 and increased the expression of dopamine transporter (DAT) in the DS from methamphetamine, but not sucrose rats. Sucrose density gradient fractionation was performed in behavior-naïve controls, D1RshRNA- and D1R-intact rats to determine the subcellular localization of D1Rs, DAT and D1R signaling proteins. D1Rs, DAT, MAPK-1 and PSD-95 predominantly localized to heavy fractions, and the membrane/lipid raft protein caveolin-1 (Cav-1) and flotillin-1 were distributed equally between buoyant and heavy fractions in controls. Methamphetamine increased localization of PSD-95, Cav-1, and flotillin-1 in D1RshRNA and D1R-intact rats to buoyant fractions. Our studies indicate that reduced D1R expression in the DS increases vulnerability to methamphetamine addiction-like behavior, and this is accompanied by striatal alterations in the expression of DAT and D1R signaling proteins and is independent of the subcellular localization of these proteins.