Single cocaine exposure does not alter striatal pre‐synaptic dopamine function in mice: an [18F]‐FDOPA PET study. Issue 5 (26th October 2017)

• Record Type: Journal Article
• Authors: Bonsall, David R; Kokkinou, Michelle; Veronese, Mattia; Coello, Christopher; Wells, Lisa A.; Howes, Oliver D.
• Is Part Of: Journal of neurochemistry. Volume 143:Issue 5(2017)
• Page Start: 551
• Page End: 560
• Publication Date: 2017-10-26
• Subjects: behaviour -- cocaine -- dopamine -- mouse -- PET; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.14223
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Cocaine is a recreational drug of abuse that binds to the dopamine transporter, preventing reuptake of dopamine into pre‐synaptic terminals. The increased presence of synaptic dopamine results in stimulation of both pre‐ and post‐synaptic dopamine receptors, considered an important mechanism by which cocaine elicits its reinforcing properties. However, the effects of acute cocaine administration on pre‐synaptic dopamine function remain unclear. Non‐invasive imaging techniques such as positron emission tomography have revealed impaired pre‐synaptic dopamine function in chronic cocaine users. Similar impairments have been seen in animal studies, with microdialysis experiments indicating decreased basal dopamine release. Here we use micro positron emission tomography imaging techniques in mice to measure dopamine synthesis capacity and determine the effect of acute cocaine administration of pre‐synaptic dopamine function. We show that a dose of 20 mg/kg cocaine is sufficient to elicit hyperlocomotor activity, peaking 15–20 min post treatment ( p < 0.001). However, dopamine synthesis capacity in the striatum was not significantly altered by acute cocaine treatment ( K i Cer : 0.0097 per min vs. 0.0112 per min in vehicle controls, p > 0.05). Furthermore, expression levels of two key enzymes related to dopamine synthesis, tyrosine hydroxylase and aromaticl ‐amino acid decarboxylase, within the striatum of scanned mice were not significantly affected by acute cocaine pre‐treatment ( p > 0.05). Our findings suggest that while the regulation of dopamine synthesis and release in the striatum have been shown to change with chronic cocaine use, leading to a reduced basal tone, these adaptations to pre‐synaptic dopaminergic neurons are not initiated following a single exposure to the drug. Abstract : Cocaine blocks the reuptake of synaptic dopamine via the dopamine transporter. Here we have used [ 18 F]‐FDOPA µPET to determine the effects of acute cocaine exposure on dopamine synthesis and storage in mice. At a dose that causes hyperlocomotor activity, a single exposure to cocaine does not significantly alter the kinetic parameters of pre‐synaptic dopamine function in the striatum.