Amphetamine regulates NR2B expression in Go2α knockout mice and thereby sustains behavioral sensitization.
The α-subunit of Go2 is a regulator of dopamine (DA) homeostasis. Deletion of the protein results in an imbalance of the direct and indirect DA pathway by reducing D1 and increasing D2 receptors. As a result, cocaine-induced behavioral sensitization is abolished. Here we show that repeated amphetamine injections in Go2α-/- mice induced a similar D1/D2 receptor ratio shift as cocaine but surprisingly the knockouts developed normal behavioral sensitization. DA receptor signaling following either cocaine or amphetamine treatment was also similar in Go2α-/- mice suggesting another mechanism involved in the differential behavioral response. Evidence is increasing that DA-glutamate interactions in the striatum determine psychostimulant action. In this line, repeated amphetamine injections led to a twofold increase in the amount of the NMDA receptor subunit NR2B in Go2α-/- mice resulting in an enhanced inhibition of the indirect DA pathway. This effect is not seen after cocaine treatment. Furthermore, amphetamine but not cocaine treatment maintained the ratio between the glutamate receptor mGluR1/5 interacting proteins Homer and Homer1a in the knockouts thereby sustaining the direct pathway. We conclude that amphetamine provokes behavioral sensitization in Go2α-/- mice by an enhanced inhibition of the indirect pathway without disturbing the direct pathway thereby overcoming the imbalance in the DArgic system.
Brunk
Irene
I
Center for Anatomy, Institute for Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Sanchis-Segura
Carles
C
Blex
Christian
C
Perreau-Lenz
Stéphanie
S
Bilbao
Ainhoa
A
Spanagel
Rainer
R
Ahnert-Hilger
Gudrun
G
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D015153:Blotting, Western; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists / Q000378:metabolism; D051960:GTP-Binding Protein alpha Subunit, Gi2 / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D047468:Immunoprecipitation; D051379:Mice; D018345:Mice, Knockout; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis* / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013134:Spiperone / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D000697:Central Nervous System Stimulants; D018492:Dopamine Antagonists; C121001:NR2B NMDA receptor; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D016194:Receptors, N-Methyl-D-Aspartate; D013134:Spiperone; D000661:Amphetamine; D051960:GTP-Binding Protein alpha Subunit, Gi2; D004298:Dopamine