title: Attenuated response to methamphetamine sensitization and deficits in motor learning and memory after selective deletion of β-catenin in dopamine neurons.
abstract: In the present study, we analyzed mice with a targeted deletion of β-catenin in DA neurons (DA-βcat KO mice) to address the functional significance of this molecule in the shaping of synaptic responses associated with motor learning and following exposure to drugs of abuse. Relative to controls, DA-βcat KO mice showed significant deficits in their ability to form long-term memories and displayed reduced expression of methamphetamine-induced behavioral sensitization after subsequent challenge doses with this drug, suggesting that motor learning and drug-induced learning plasticity are altered in these mice. Morphological analyses showed no changes in the number or distribution of tyrosine hydroxylase-labeled neurons in the ventral midbrain. While electrochemical measurements in the striatum determined no changes in acute DA release and uptake, a small but significant decrease in DA release was detected in mutant animals after prolonged repetitive stimulation, suggesting a possible deficit in the DA neurotransmitter vesicle reserve pool. However, electron microscopy analyses did not reveal significant differences in the content of synaptic vesicles per terminal, and striatal DA levels were unchanged in DA-βcat KO animals. In contrast, striatal mRNA levels for several markers known to regulate synaptic plasticity and DA neurotransmission were altered in DA-βcat KO mice. This study demonstrates that ablation of β-catenin in DA neurons leads to alterations of motor and reward-associated memories and to adaptations of the DA neurotransmitter system and suggests that β-catenin signaling in DA neurons is required to facilitate the synaptic remodeling underlying the consolidation of long-term memories.
authors: Integrative Neuroscience Section, National Institutes of Health, Baltimore, Maryland 21224, USA.
authors: Oscar
authors: O
authors: Diaz-Ruiz
authors: Yajun
authors: Y
authors: Zhang
authors: Lufei
authors: L
authors: Shan
authors: Nasir
authors: N
authors: Malik
authors: Alexander F
authors: AF
authors: Hoffman
authors: Bruce
authors: B
authors: Ladenheim
authors: Jean Lud
authors: JL
authors: Cadet
authors: Carl R
authors: CR
authors: Lupica
authors: Adriana
authors: A
authors: Tagliaferro
authors: Alicia
authors: A
authors: Brusco
authors: Cristina M
authors: CM
authors: Bäckman
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000235:genetics; D000818:Animals; D001703:Biophysics; D004195:Disease Models, Animal; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D059290:Dopaminergic Neurons / Q000187:drug effects*; D004558:Electric Stimulation; D050485:GABA Plasma Membrane Transport Proteins / Q000235:genetics; D018737:Hand Strength / Q000502:physiology; D066298:In Vitro Techniques; D007859:Learning Disabilities / Q000235:genetics*; D008124:Locomotion / Q000187:drug effects / Q000235:genetics; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D042282:Microdissection; D009043:Motor Activity / Q000187:drug effects* / Q000235:genetics; D009473:Neuronal Plasticity / Q000187:drug effects / Q000235:genetics; D045442:Rotarod Performance Test; D013378:Substantia Nigra / Q000166:cytology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D017557:Ventral Tegmental Area / Q000166:cytology; D051176:beta Catenin / Q000172:deficiency* / Q000235:genetics
chemical_list: C495267:CTNNB1 protein, mouse; D018765:Dopamine Uptake Inhibitors; D050485:GABA Plasma Membrane Transport Proteins; C493414:Slc6a1 protein, mouse; D051176:beta Catenin; D008694:Methamphetamine; D014446:Tyrosine 3-Monooxygenase