Neuroimmune interactions have emerged as critical modulators of substance use disorders and may represent promising translational therapeutic targets. In prior work, we demonstrated that the cytokine granulocyte colony stimulating factor (G-CSF) is elevated in mice following cocaine exposure, with circulating levels correlating with cocaine intake and locomotor sensitization. Additionally, exogenous G-CSF enhances cocaine reward and increases low-dose cocaine self-administration. We have further shown that repeated G-CSF administration alters expression of glutamatergic synapse-associated proteins following cocaine-seeking behavior. Building on these findings, the present studies examined the molecular consequences of repeated administration of G-CSF, cocaine, or their combination, with a focus on glutamatergic signaling pathways. We also tested whether altered glutamate receptor expression contributes to G-CSF-mediated enhancement of cocaine reward. Repeated combined administration of G-CSF and cocaine produced robust changes in glutamate-associated and synapse-related protein expression within the nucleus accumbens and medial prefrontal cortex. These molecular adaptations were accompanied by increased synaptic density in the nucleus accumbens. Finally, pharmacological inhibition of calcium-permeable AMPA receptors within the nucleus accumbens reversed the G-CSF-induced enhancement of cocaine conditioned place preference. Together, these findings indicate that G-CSF enhances cocaine reward at least in part by promoting glutamatergic synaptic remodeling in the nucleus accumbens, identifying a neuroimmune-glutamate mechanism that may be leveraged for therapeutic intervention.
Hofford et al. (Mon,) studied this question.