TY - JOUR T1 - Cholinergic Interneurons Underlie Spontaneous Dopamine Release in Nucleus Accumbens JF - The Journal of Neuroscience JO - J. Neurosci. DO - 10.1523/JNEUROSCI.3064-16.2017 SP - 3064-16 AU - Jordan T. Yorgason AU - Douglas M. Zeppenfeld AU - John T. Williams Y1 - 2017/01/23 UR - http://www.jneurosci.org/content/early/2017/01/23/JNEUROSCI.3064-16.2017.abstract N2 - The release of dopamine from terminals in the nucleus accumbens (NAc) is regulated by a number of factors, including voltage gated ion channels, D2-autoreceptors and nicotinic acetylcholine receptors (nAChRs). Cholinergic interneurons (CINs) drive dopamine release through activation of nAChRs on dopamine terminals. Using cyclic voltammetry in mouse brain slices, nAChR-dependent spontaneous dopamine transients and the mechanisms underlying the origin were examined in the NAc. Spontaneous events were infrequent (0.3 per minute), but the rate and amplitude were increased after blocking Kv channels with 4-aminopyridine. Although, the firing frequency of CINs was increased by blocking glutamate reuptake with TBOA and the Sk blocker apamin, only 4-aminopyridine increased the frequency of dopamine transients. In contrast, inhibition of CIN firing with the μ/δ selective opioid [Met5]enkephalin (1 μM) decreased spontaneous dopamine transients. Cocaine increased the rate and amplitude of dopamine transients, suggesting that the activity of the dopamine transporter limits the detection of these events. In the presence of cocaine, the rate of spontaneous dopamine transients was further increased after blocking D2-autoreceptors. Blockade of muscarinic receptors had no effect on evoked dopamine release suggesting that feedback inhibition of acetylcholine release was not involved. Thus, while spontaneous dopamine transients are reliant on nAChRs, the frequency was not strictly governed by the activity of CINs. The increase in frequency of spontaneous dopamine transients induced by cocaine was not due to an increase in cholinergic tone and are likely a product of an increase in detection resulting from decreased dopamine reuptake.SIGNIFICANCE STATEMENTThe actions of dopamine in the nucleus accumbens are thought to be responsible for endogenous reward and the reinforcing properties of drugs of abuse, such as psychostimulants. The present work examines the mechanisms underlying nicotinic acetylcholine receptor induced spontaneous dopamine release. This study demonstrates that spontaneous dopamine release is (1) dependent of the activation of nicotinic receptors (2) independent on the spontaneous activity of cholinergic interneurons and (3) that cocaine increased the detection of dopamine transients by prolonging the presence and increasing the diffusion of dopamine in the extracellular space. The release of acetylcholine is therefore responsible for spontaneous dopamine transients and cocaine augments dopamine tone without altering activity of cholinergic interneurons. ER -