This proposal continues our characterization of the role of neurotrophic signaling pathways in the neural plasticity induced in the ventral tegmental area (VTA)-nucleus accumbens (NAc) reward circuit by chronic exposure to opiate or stimulant drugs of abuse. The proposal has three Aims: 1) to delineate the cell-type specific actions of BDNF-TrkB signaling in the VTA-NAc in regulating molecular, cellular, and behavioral responses to opiates and cocaine;2) to delineate the adaptations in BDNF-TrkB signaling cascades that mediate the ability of opiates to induce morphological changes in VTA dopamine neurons;and 3) to delineate the adaptations in BDNF-TrkB signaling cascades that mediate the ability of cocaine and opiates to induce opposite morphological changes in NAc medium spiny neurons. We have made important progress in each of these Aims over the past 5 years, and have substantial preliminary data to support highly penetrating and mechanistic studies over the proposed new grant period. Using genetic mutant mice and viral-mediated gene transfer, which has enabled highly localized knockouts of BDNF or TrkB within the VTA or NAc of adult animals, we have demonstrated distinct roles for BDNF-TrkB signaling in regulating responses to opiates and cocaine. Using more advanced tools, which now enable such knockouts in specific neuronal cell types within these brain regions, we will characterize the specific influence of D1 vs. D2 containing NAc medium spiny neurons, and VTA dopamine neurons, in these phenomena. One of the most dramatic changes that opiates induce in VTA dopamine neurons is a decrease in their overall size. This decrease is mediated by an impairment in BDNF signaling within these neurons, specifically, downregulation of the IRS-AKT pathway. We now have evidence that this downregulation is part of overall opiate-induced adaptations in AKT-RHEB-mTOR signaling. The proposed experiments are designed to further establish the detailed molecular events that underlie this morphological adaptation. In contrast, cocaine and opiates induce distinct changes in NAc medium spiny neurons: cocaine increases, whereas opiates decrease, the neurons'dendritic arborizations and spine density. We have shown that these adaptations too involve altered BDNF signaling, and now propose to further characterize the precise changes in neurotrophic signaling pathways, including changes in NF?B signaling that mediate these adaptations. Together, the proposed experiments will provide fundamentally new insight into the dramatic ways in which opiates and stimulants change VTA-NAc neurons, information which could be mined in future years to define improved diagnostic tests and treatments for drug addiction.

Public Health Relevance

The objective of this grant is to study the role of neurotrophic signaling pathways, acting in the brain's reward circuits, in drug abuse models in mice. We investigate the influence of chronic exposure to drugs of abuse on levels and activity of these complex signaling pathways within brain reward regions. We then manipulate the activity of specific signaling proteins in reward regions by use of genetic mutant mice or viral mediated gene transfer, and study the molecular, cellular, and behavioral consequences of these manipulations. Together, these studies promise to provide fundamentally novel information concerning how drugs of abuse alter the brain's reward circuits after chronic administration, and to offer new leads toward the development of improved diagnostic tests and more effective treatments of drug addiction.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA014133-14
Application #
8463490
Study Section
Molecular Neuropharmacology and Signaling Study Section (MNPS)
Program Officer
Pilotte, Nancy S
Project Start
2000-09-01
Project End
2015-04-30
Budget Start
2013-05-01
Budget End
2014-04-30
Support Year
14
Fiscal Year
2013
Total Cost
$396,367
Indirect Cost
$162,522
Name
Icahn School of Medicine at Mount Sinai
Department
Neurosciences
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
Damez-Werno, Diane M; Sun, HaoSheng; Scobie, Kimberly N et al. (2016) Histone arginine methylation in cocaine action in the nucleus accumbens. Proc Natl Acad Sci U S A 113:9623-8
Ma, Yao-Ying; Wang, Xiusong; Huang, Yanhua et al. (2016) Re-silencing of silent synapses unmasks anti-relapse effects of environmental enrichment. Proc Natl Acad Sci U S A 113:5089-94
Cahill, Michael E; Bagot, Rosemary C; Gancarz, Amy M et al. (2016) Bidirectional Synaptic Structural Plasticity after Chronic Cocaine Administration Occurs through Rap1 Small GTPase Signaling. Neuron 89:566-82
Calipari, Erin S; Bagot, Rosemary C; Purushothaman, Immanuel et al. (2016) In vivo imaging identifies temporal signature of D1 and D2 medium spiny neurons in cocaine reward. Proc Natl Acad Sci U S A 113:2726-31
Wook Koo, Ja; Labonté, Benoit; Engmann, Olivia et al. (2016) Essential Role of Mesolimbic Brain-Derived Neurotrophic Factor in Chronic Social Stress-Induced Depressive Behaviors. Biol Psychiatry 80:469-78
Graziane, Nicholas M; Sun, Shichao; Wright, William J et al. (2016) Opposing mechanisms mediate morphine- and cocaine-induced generation of silent synapses. Nat Neurosci 19:915-25
Khibnik, Lena A; Beaumont, Michael; Doyle, Marie et al. (2016) Stress and Cocaine Trigger Divergent and Cell Type-Specific Regulation of Synaptic Transmission at Single Spines in Nucleus Accumbens. Biol Psychiatry 79:898-905
Koo, Ja Wook; Mazei-Robison, Michelle S; LaPlant, Quincey et al. (2015) Epigenetic basis of opiate suppression of Bdnf gene expression in the ventral tegmental area. Nat Neurosci 18:415-22
Li, Xuan; Rubio, F Javier; Zeric, Tamara et al. (2015) Incubation of methamphetamine craving is associated with selective increases in expression of Bdnf and trkb, glutamate receptors, and epigenetic enzymes in cue-activated fos-expressing dorsal striatal neurons. J Neurosci 35:8232-44
Dias, Caroline; Dietz, David; Mazei-Robison, Michelle et al. (2015) Dishevelled-2 regulates cocaine-induced structural plasticity and Rac1 activity in the nucleus accumbens. Neurosci Lett 598:23-8

Showing the most recent 10 out of 48 publications