Present address: Department of Cognitive Neurobiology, Center for Brain Research, Medical University Vienna, 1090 Vienna, Austria.
Different stressors produce excitation or inhibition of mesolimbic dopamine neuron activity: response alteration by stress pre-exposure
Article first published online: 18 APR 2012
© 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Volume 35, Issue 8, pages 1312–1321, April 2012
How to Cite
Valenti, O., Gill, K. M. and Grace, A. A. (2012), Different stressors produce excitation or inhibition of mesolimbic dopamine neuron activity: response alteration by stress pre-exposure. European Journal of Neuroscience, 35: 1312–1321. doi: 10.1111/j.1460-9568.2012.08038.x
- Issue published online: 18 APR 2012
- Article first published online: 18 APR 2012
- Received 6 August 2011, revised 3 January 2012, accepted 17 January 2012
- amphetamine cross-sensitization;
- DA neuron population activity;
- prefrontal cortex;
- ventral tegmental area
Stressors can exert a wide variety of responses, ranging from adaptive responses to pathological changes; moreover, recent studies suggest that mild stressors can attenuate the response of a system to major stressful events. We have previously shown that 2-week exposure to cold, a comparatively mild inescapable stressor, induced a pronounced reduction in ventral tegmental area (VTA) dopamine (DA) neuron activity, whereas restraint stress increases DA neuron activity. However, it is not known if these stressors differentially impact the VTA in a region-specific manner, if they differentially impact behavioral responses, or whether the effects of such different stressors are additive or antagonistic with regard to their impact on DA neuron firing. To address these questions, single-unit extracellular recordings were performed in anesthetized control rats and rats exposed to chronic cold, and tested after delivery of a 2-h restraint session. Chronic cold stress strongly attenuated the number of DA neurons firing in the VTA, and this effect occurred primarily in the medial and central VTA regions that preferentially project to reward-related ventral striatal regions. Chronic cold exposure also prevented the pronounced increase in DA neuron population activity without affecting the behavioral sensitization to amphetamine produced by restraint stress. Taken together, these data show that a prolonged inescapable mild stressor can induce plastic changes that attenuate the DA system response to acute stress.