Stress produces aversion and potentiates cocaine reward by releasing endogenous dynorphins in the ventral striatum to locally stimulate serotonin reuptake

• Published in: The Journal of neuroscience 2012-12, Vol.32 (49), p.17582-17596
• Main Authors: Schindler, Abigail G, Messinger, Daniel I, Smith, Jeffrey S, Shankar, Haripriya, Gustin, Richard M, Schattauer, Selena S, Lemos, Julia C, Chavkin, Nicholas W, Hagan, Catherine E, Neumaier, John F, Chavkin, Charles
• Format: Article
• Language: English
• Subjects: Animals; Avoidance Learning - drug effects; Avoidance Learning - physiology; Brain - metabolism; Cocaine - pharmacology; Corpus Striatum - metabolism; Dopamine - metabolism; Dynorphins - metabolism; Dynorphins - physiology; G-Protein-Coupled Receptor Kinase 3 - genetics; G-Protein-Coupled Receptor Kinase 3 - physiology; Male; Membrane Transport Proteins - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Microinjections - methods; Naltrexone - administration & dosage; Naltrexone - analogs & derivatives; Naltrexone - pharmacology; Narcotic Antagonists - administration & dosage; Narcotic Antagonists - pharmacokinetics; Nicotine - adverse effects; Nucleus Accumbens - drug effects; Nucleus Accumbens - metabolism; p38 Mitogen-Activated Protein Kinases - genetics; p38 Mitogen-Activated Protein Kinases - physiology; Raphe Nuclei - drug effects; Raphe Nuclei - metabolism; Raphe Nuclei - physiology; Receptors, Opioid, kappa - antagonists & inhibitors; Receptors, Opioid, kappa - physiology; Reward; Serotonin - metabolism; Serotonin Plasma Membrane Transport Proteins - genetics; Serotonin Plasma Membrane Transport Proteins - metabolism; Signal Transduction - drug effects; Signal Transduction - physiology; Stress, Psychological - metabolism; Stress, Psychological - psychology; Substance Withdrawal Syndrome - metabolism; Synaptosomes - metabolism
• ISSN: 0270-6474; 1529-2401; 1529-2401
• DOI: 10.1523/JNEUROSCI.3220-12.2012

Activation of the dynorphin/κ-opioid receptor (KOR) system by repeated stress exposure or agonist treatment produces place aversion, social avoidance, and reinstatement of extinguished cocaine place preference behaviors by stimulation of p38α MAPK, which subsequently causes the translocation of the serotonin transporter (SERT, SLC6A4) to the synaptic terminals of serotonergic neurons. In the present study we extend those findings by showing that stress-induced potentiation of cocaine conditioned place preference occurred by a similar mechanism. In addition, SERT knock-out mice did not show KOR-mediated aversion, and selective reexpression of SERT by lentiviral injection into the dorsal raphe restored the prodepressive effects of KOR activation. Kinetic analysis of several neurotransporters demonstrated that repeated swim stress exposure selectively increased the V(max) but not K(m) of SERT without affecting dopamine transport or the high-capacity, low-affinity transporters. Although the serotonergic neurons in the dorsal raphe project throughout the forebrain, a significant stress-induced increase in cell-surface SERT expression was only evident in the ventral striatum, and not in the dorsal striatum, hippocampus, prefrontal cortex, amygdala, or dorsal raphe. Stereotaxic microinjections of the long-lasting KOR antagonist norbinaltorphimine demonstrated that local KOR activation in the nucleus accumbens, but not dorsal raphe, mediated this stress-induced increase in ventral striatal surface SERT expression. Together, these results support the hypothesis that stress-induced activation of the dynorphin/KOR system produces a transient increase in serotonin transport locally in the ventral striatum that may underlie some of the adverse consequences of stress exposure, including the potentiation of the rewarding effects of cocaine.