Characterization of Proteomic Changes in the Nucleus Accumbens in Response to Chronic Granulocyte-colony Stimulating Factor and Cocaine

Cocaine addiction is a chronic relapsing disorder that leads to significant morbidity, and for which there are currently no FDA-approved pharmacotherapies. In recent years, there has been a growing appreciation for the role of neuroimmune interactions in the pathogenesis of multiple psychiatric conditions – including substance use disorders. To further characterize the role of the innate immune system in models of cocaine use disorder we utilized a broad screen of serum cytokines following chronic cocaine treatment in mice. From this, we identified granulocyte-colony stimulating factor (G-CSF) as a cytokine that is upregulated both in the serum and in important limbic reward structures following cocaine treatment. Further experiments demonstrated G-CSF to be a potent modulator of neuronal and behavioral plasticity in response to cocaine, with the principle locus of this effect in the Nucleus Accumbens (NAc). While the effect of G-CSF on behavior is clear, the molecular mechanisms underlying its effect remain to be clarified. Multiple previous studies have demonstrated the G-CSF receptor to be expressed on neurons throughout the brain, and it is known to signal through multiple intracellular signaling cascades important for synaptic plasticity including Jak/STAT, Akt and ERK pathways. Here, we propose to utilize the cutting edge mass spectrometry protein profiling techniques available at the Yale/NIDA Neuroproteomics Center to directly assess the molecular effects of G-CSF on the NAc in two distinct aims: (1) Utilizing the iTRAQ proteomic profiling technology we will seek to perform whole-proteome discovery analysis to identify regulated proteins in whole NAc tissue punches from animals treated with ± G-CSF ± cocaine in a 2 x 2 design, and (2) To identify synapse-specific targets of G-CSF treatment we will utilize the PSD/MRM technology developed by the Neuroproteomics Center to perform targeted analyses of purified NAc synaptosomes from G-CSF and cocaine treated mice. Overall, the proposed research will clarify the molecular signaling underlying this newly identified potent modulator of neuronal and behavioral response to cocaine. These data will serve both to clarify the underlying neurobiology, and to develop targeted approaches to study this novel translationally-relevant signaling pathway.