Chunk #23 — Results — Widespread effects of cocaine and withdrawal on catecholaminergic, GABAergic, cholinergic, glutamatergic, and endocannabinoid pathways
showed a sustained increase while expression of Grik4 and Grik5 showed a sustained decrease. Expression of the five most-highly expressed metabotropic receptors for glutamate (Grm1, Grm3, Grm4, Grm5, and Grm7) showed a sustained increase. Vesicular glutamate transporters (Vglut) can be expressed in GABAergic and cholinergic neurons as well as in glial cells (El Mestikawy et al., 2011). Transcripts encoding all three Vgluts were detectable in the NAc, which contains no primarily glutamatergic neurons; expression of Vglut1 mRNA exceeded that of Vglut2. Na+-dependent plasma membrane glutamate transporters (Eaat1 through Eaat5), which remove glutamate from the synaptic cleft and perisynaptic area, also play a critical role in glutamatergic transmission. Three of the four Eaats expressed in the NAc (Eaat1, Eaat2, and Eaat3) exhibited a sustained increase in expression while Eaat4 exhibited reduced expression in Withdrawal. Eaat1 and Eaat2 are primarily expressed in glia, while Eaat3, Eaat4 and Eaat5 show widespread neuronal expression throughout the brain (Tzingounis and Wadiche, 2007).
