Knockdown of ventral tegmental area mu-opioid receptors in rats prevents effects of social defeat stress: Implications for amphetamine cross-sensitization, social avoidance, weight regulation and expression of brain-derived neurotrophic factor

NEUROPHARMACOLOGY

卷:89

Article

Johnston, Caitlin E.^1,2  Herschel, Daniel J.^1,2  Lasek, Amy W.^5,6  Hammer, Ronald P., Jr.^1,2,3,4  Nikulina, Ella M.^1,2 

[1] Univ Arizona, Coll Med, Dept Basic Med Sci, Phoenix, AZ 85004 USA

[2] Arizona State Univ, Interdisciplinary Neurosci Program, Tempe, AZ USA

[3] Univ Arizona, Coll Med, Dept Pharmacol, Phoenix, AZ 85004 USA

[4] Univ Arizona, Coll Med, Dept Psychiat, Phoenix, AZ 85004 USA

[5] Univ Calif San Francisco, Dept Neurol, Ernest Gallo Clin, Emeryville, CA USA

[6] Univ Calif San Francisco, Dept Neurol, Res Ctr, Emeryville, CA USA

关键词: Mu-opioid receptor;    Social defeat stress;    Ventral tegmental area;    Cross-sensitization;    Brain-derived neurotrophic factor;    Amphetamine;   

DOI  :  10.1016/j.neuropharm.2014.10.010

来源: Elsevier

【 摘 要 】

Social defeat stress causes social avoidance and long-lasting cross-sensitization to psychostimulants, both of which are associated with increased brain-derived neurotrophic factor (BDNF) expression in the ventral tegmental area (VTA). Moreover, social stress upregulates VTA mu-opioid receptor (MOR) mRNA. In the VTA, MOR activation inhibits GABA neurons to disinhibit VTA dopamine neurons, thus providing a role for VTA MORs in the regulation of psychostimulant sensitization. The present study determined the effect of lentivirus-mediated MOR knockdown in the VTA on the consequences of intermittent social defeat stress, a salient and profound stressor in humans and rodents. Social stress exposure induced social avoidance and attenuated weight gain in animals with non-manipulated VTA MORs, but both these effects were prevented by VTA MOR knockdown. Rats with non-manipulated VTA MOR expression exhibited cross-sensitization to amphetamine challenge (1.0 mg/kg, i.p.), evidenced by a significant augmentation of locomotion. By contrast, knockdown of VTA MORs prevented stress-induced cross-sensitization without blunting the locomotor-activating effects of amphetamine. At the time point corresponding to amphetamine challenge, immunohistochemical analysis was performed to examine the effect of stress on VTA BDNF expression. Prior stress exposure increased VTA BDNF expression in rats with non-manipulated VTA MOR expression, while VTA MOR knockdown prevented stress-induced expression of VTA BDNF. Taken together, these results suggest that upregulation of VTA MOR is necessary for the behavioral and biochemical changes induced by social defeat stress. Elucidating VTA MOR regulation of stress effects on the mesolimbic system may provide new therapeutic targets for treating stress-induced vulnerability to substance abuse. (C) 2014 Elsevier Ltd. All rights reserved.

【 授权许可】

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