Real-time monitoring of electrically evoked catecholamine signals in the songbird striatum using in vivo fast-scan cyclic voltammetry

Abstract

Fast-scan cyclic voltammetry is a powerful technique for monitoring rapid changes in extracellular neurotransmitter levels in the brain. In vivo fast-scan cyclic voltammetry has been used extensively in mammalian models to characterize dopamine signals in both anesthetized and awake preparations, but has yet to be applied to a non-mammalian vertebrate. The goal of this study was to establish in vivo fast-scan cyclic voltammetry in a songbird, the European starling, to facilitate real-time measurements of extracellular catecholamine levels in the avian striatum. In urethane-anesthetized starlings, changes in catecholamine levels were evoked by electrical stimulation of the ventral tegmental area and measured at carbon-fiber microelectrodes positioned in the medial and lateral striata. Catecholamines were elicited by different stimulations, including trains related to phasic dopamine signaling in the rat, and were analyzed to quantify presynaptic mechanisms governing exocytotic release and neuronal uptake. Evoked extracellular catecholamine dynamics, maximal amplitude of the evoked catecholamine signal, and parameters for catecholamine release and uptake did not differ between striatal regions and were similar to those determined for dopamine in the rat dorsomedial striatum under similar conditions. Chemical identification of measured catecholamine by its voltammogram was consistent with the presence of both dopamine and norepinephrine in striatal tissue content. However, the high ratio of dopamine to norepinephrine in tissue content and the greater sensitivity of the carbon-fiber microelectrode to dopamine compared to norepinephrine favored the measurement of dopamine. Thus, converging evidence suggests that dopamine was the predominate analyte of the electrically evoked catecholamine signal measured in the striatum by fast-scan cyclic voltammetry. Overall, comparisons between the characteristics of these evoked signals suggested a similar presynaptic regulation of dopamine in the starling and rat striatum. Fast-scan cyclic voltammetry thus has the potential to be an invaluable tool for investigating the neural underpinnings of behavior in birds.

Autoradiographic localization of [3H]-Nisoxetine binding sites in the CNS of male and female Japanese quail

“…For example, the MSt and LSt in quail are thought to be close analogs to the striatum and nucleus accumbens in mammals (Kleitz et al, 2009;Reiner et al, 2004). Previous research has shown that the striatum is more heavily innervated by DA compared to NE in both birds (Cornil & Ball, 2008;Smith et al, 2015) and mammals (Del Pino et al, 2011;Jacobowitz & Richardson, 1978). In the current study, NET binding was high in the striatum of the quail brain.…”

A novel carbon tipped single micro-optrode for combined optogenetics and electrophysiology

“…In our experience, we also observed that a simple pull of CF into a glass-coated microelectrode did not provide a tight seal between the two components. Improvements to the CF–glass seal were later perfected by using polyester [ 30 ] or epoxy [ 31 – 33 ] sealants, polishing by heat [ 34 ], or pulling CF into a thickened glass sheathing [ 35 ]. However, unlike the case of glass-coated tungsten microelectrodes [ 36 , 37 ], no obvious relationship between carbon tip length and impedance has been established to date.…”

Sound‐induced monoaminergic turnover in the auditory forebrain depends on endocrine state in a seasonally‐breeding songbird

“…First, we measured monoamine turnover in dissected tissue, which does not afford the best time resolution. Methods of measuring release in real time, such as voltammetry, should be employed to better detect event‐related release. Second, our definition of monoamine turnover is based on the assumption that an increase in metabolites, relative to the concentration of the monoamines themselves, indicates release.…”