Acute in vivo nicotine administration enhances synchrony among dopamine neurons

• Published in: Biochemical pharmacology Vol. 82; no. 8; pp. 977 - 983
• Main Authors: Li, Wei, Doyon, William M., Dani, John A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier Inc 15-10-2011; Elsevier
• Subjects: Action Potentials - drug effects; Animals; Biological and medical sciences; Correlation; covariance; dopamine; Dopamine - metabolism; drugs; Male; Medical sciences; Mesolimbic; Microelectrodes; neurons; Neurons - drug effects; Neurons - metabolism; nicotine; Nicotine - administration & dosage; Nicotine - pharmacology; Nicotine addiction; Nicotinic acetylcholine receptors; Pharmacology. Drug treatments; Rats; Rats, Long-Evans; Reinforcement (Psychology); Synchronization; Tobacco, tobacco smoking; Toxicology; Ventral tegmental area; Ventral Tegmental Area - drug effects; Ventral Tegmental Area - metabolism; VTA; Correlation; ACh; SNc; Nicotine addiction; Synchronization; NAc; nAChR; DHβE; Nicotinic acetylcholine receptors; Mesolimbic; DA; Ventral tegmental area; ISI; Acute; Central nervous system; Tobacco smoking; Encephalon; In vivo; Alkaloid; Cholinergic receptor; Addiction; Dopaminergic neuron; Nicotinic receptor; Nicotine
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2011.06.006

Nicotine increases the firing rates and increases synchronization of dopamine neurons.
Altered functional interactions among midbrain dopamine (DA) neurons contribute to the reinforcing properties of environmental stimuli and addictive drugs. To examine correlations among DA neurons, acute nicotine was administrated to rats via an intraperitoneal catheter and unit activity was measured using multi-tetrode in vivo recordings. Nicotine administration enhanced the correlated activity of simultaneously recorded DA neurons from the ventral tegmental area (VTA). The strength of the correlations between DA neuron pairs, as measured by cross covariance among two spike trains, showed dynamic changes over time. Nicotine produced a gradual rise in firing rate and burst activity that reached a stable plateau approximately 20
min after the intraperitoneal nicotine infusion. Shortly after that time the cross correlations measured using 5-ms bins increased significantly above baseline. In addition, nicotine increased the firing rates of DA neurons in the posterior VTA more than in the anterior VTA. Unlike nicotine, eticlopride administration also boosted DA neuron firing activity but did not enhance synchronization, indicating that the cross correlations induced by nicotine were not due to a non-specific increase in firing rate. The overall results show that nicotine induces nearly synchronous firing by a subset of DA neurons, and those changes in correlative firing will enhance the DA signal that contributes to nicotine-induced behavioral reinforcement.