期刊
PAIN
卷 142, 期 3, 页码 236-244出版社
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1016/j.pain.2009.01.011
关键词
Hyperalgesia; Pain-modulation; Rostral ventromedial medulla; Brainstem; ON-cells; OFF-cells
资金
- NINDS [NS 40365]
- NIDA [DA 05608]
Intense stress and fear have long been known to give rise to a suppression of pain termed stress-induced analgesia, mediated by brainstem pain-modulating circuitry, including pain-inhibiting neurons of the rostral ventromedial medulla. However, stress does not invariably suppress pain, and indeed, may exacerbate it. Although there is a growing support for the idea of stress-induced hyperalgesia, the neurobiological basis for this effect remains almost entirely unknown. Using simultaneous single-cell recording and functional analysis, we show here that stimulation of the dorsomedial nucleus of the hypothalamus, known to be a critical component of central mechanisms mediating neuroendocrine, cardiovascular and thermogenic responses to mild or emotional stressors such as air puff, also triggers thermal hyperalgesia by recruiting pain-facilitating neurons ON-cells, in the rostral ventromedial medulla. Activity of identified RVM ON-cells OFF-cells and NEUTRAL cells. nocieptive withdrawal thresholds rectal temperature , and heart rate were recorded in lightly anethetized rats. In addition to the expected increases in body temperature and heart rate, disinhibition of the DMH induced a robust activation of ON-cells, suppression of OFF-cell firing and behavioral hyperalgesia. Blocking ON-cell activation prevented hyperalgesia, but did not interfere with DMH-induced thermogenesis or tachycardia, pointing to differentiation of neural substrates for autonomic and nociceptive modulation within the RVM. These data demonstrate a top-down activation of brainstem pain-facilitating neurons, and suggest a possible neural circuit for stress-induced hyperalgesia. (C) 2009 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.
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