Granulocyte-Colony Stimulating Factor reduces cocaine-seeking and downregulates glutamatergic synaptic proteins in medial prefrontal cortex

Abstract

Background: Psychostimulant use disorder is a major public health issue, and despite the scope of the problem there are currently no FDA approved treatments. There would be tremendous utility in development of a treatment that could help patients both achieve and maintain abstinence. Previous work from our group has identified granulocyte-colony stimulating factor (G-CSF) as a neuroactive cytokine that alters behavioral response to cocaine, increases synaptic dopamine release, and enhances cognitive flexibility. Here, we investigate the role of G-CSF in affecting extinction and reinstatement of cocaine-seeking and perform detailed characterization of its proteomic effects in multiple limbic substructures.Methods: Sprague-Dawley rats were injected with PBS or G-CSF during (1) extinction or (2) abstinence from cocaine self-administration, and drug seeking behavior was measured. Quantitative assessment of changes in the proteomic landscape in the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC) were performed via data-independent acquisition (DIA) mass spectrometry analysis.Results: Administration of G-CSF during extinction accelerated the rate of extinction, and administration during abstinence attenuated cue-induced cocaine-seeking. Analysis of global protein expression demonstrated that G-CSF regulated proteins primarily in mPFC that are critical to glutamate signaling and synapse maintenance.Conclusion: Taken together, these findings support G-CSF as a viable translational research target with the potential to reduce drug craving or seeking behaviors. Importantly, recombinant G-CSF exists as an FDAapproved medication which may facilitate rapid clinical translation. Additionally, using cutting-edge multi-region discovery proteomics analyses, these studies identify a novel mechanism underlying G-CSF effects on behavioral plasticity.

Granulocyte-colony stimulating factor (G-CSF) enhances cocaine effects in the nucleus accumbens via a dopamine release-based mechanism

“…Thus, G-CSF signaling seems to be a potent regulator of dopamine neurons that allows for regulation of dopamine release and behavioral effects, without direct agonist/antagonist effects on dopamine release in the absence of other stimuli. Importantly, we also have demonstrated that treatment with G-CSF during abstinence after cocaine self-administration can reduce subsequent drug seeking behavior 10 .…”

“…Dopamine release from terminals in the striatum is regulated by a wide range of neurotransmitter systems including acetylcholine, glutamate, GABA, various peptide systems and other types of signaling molecules (for review see Nolan et al, 2020 47 ). While we hypothesize that these effects do indeed occur through direct terminal regulation, glutamatergic neurons in the mPFC that project to the NAc are also known to play a role in the effects of G-CSF 6,10 . Thus, it is also possible that G-CSF is acting on cortical terminals in the NAc which alters NAc activity and dopamine release through a microcircuit.…”

“…Briefly, G-CSF was injected via an IP injection twice: 24 hours before voltammetric recordings and again one hour before recordings. This dose and paradigm was chosen as it is consistent with our previous work, and results in comparable systemic levels to those induced by chronic cocaine exposure [4][5][6]10 .…”

“…For injections, granulocyte colony stimulating factor (G-CSF; GenScript, Piscataway, NJ) was dissolved in 0.9% sterile saline and administered intraperitoneally (IP). G-CSF Treatment: Animals were treated with G-CSF as described previously [4][5][6]10 . Briefly, G-CSF was injected via an IP injection twice: 24 hours before voltammetric recordings and again one hour before recordings.…”

“…Accordingly, immune dysregulation has been implicated in addiction, and only recently have studies begun to examine the mechanistic link between altered immune function and the pathology underlying addictive disorders 2,[4][5][6][7][8] . Granulocyte-colony stimulating factor (G-CSF), a cytokine, is regulated by cocaine in rodents 6 and humans 9 , and is a potent modulator of behavioral plasticity induced by repeated cocaine exposure where it increases cocaine selfadministration under low effort schedules of reinforcement, enhances motivation for cocaine, increases cocaine conditioned place preference, increases sensitization, and alters drug seeking in both males and females 5,6,10 . While the behavioral effects are well-characterized, the neural basis for how this cytokine enhances stimulant effects remains to be elucidated.…”