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首页> 外文期刊>Journal of Neurophysiology >Entanglement between thermoregulation and nociception in the rat: the case of morphine
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Entanglement between thermoregulation and nociception in the rat: the case of morphine

机译：大鼠温度调节与伤害感受之间的纠缠：吗啡的情况

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摘要

In thermoneutral conditions, rats display cyclic variations of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Systemic morphine elicits their vasoconstriction followed by hyperthermia in a naloxone-reversible and dose-dependent fashion. The dose-response curves were steep with ED50 in the 0.5-1 mg/kg range. Given the pivotal functional role of the rostral ventromedial medulla (RVM) in nociception and the rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, the RVM/rMR was blocked by muscimol: it suppressed the effects of morphine. "On-" and "off-" neurons recorded in the RVM/rMR are activated and inhibited by thermal nociceptive stimuli, respectively. They are also implicated in regulating the cyclic variations of the vasomotion of the tail and paws seen in thermoneutral conditions. Morphine elicited abrupt inhibition and activation of the firing of on-and off-cells recorded in the RVM/rMR. By using a model that takes into account the power of the radiant heat source, initial skin temperature, core body temperature, and peripheral nerve conduction distance, one can argue that the morphine-induced increase of reaction time is mainly related to the morphine-induced vasoconstriction. This statement was confirmed by analyzing in psychophysical terms the tail-flick response to random variations of noxious radiant heat. Although the increase of a reaction time to radiant heat is generally interpreted in terms of analgesia, the present data question the validity of using such an approach to build a pain index.
机译：在热中性条件下，大鼠表现出尾巴和脚掌血管运动的周期性变化，这是当前急性或慢性疼痛动物模型中使用最广泛的靶器官。系统性吗啡以纳洛酮可逆和剂量依赖性的方式引起血管收缩，随后发生热疗。 ED50在0.5-1 mg / kg范围内时，剂量反应曲线陡峭。鉴于延髓腹侧延髓（RVM）在痛觉调节和延髓延髓（rMR）在体温调节中起着关键的作用，两个大面积重叠的大脑区域，RVM / rMR被麝香酚阻断：抑制了吗啡的作用。记录在RVM / rMR中的“开”和“关”神经元分别被热伤害性刺激激活和抑制。它们还涉及调节在热中性条件下观察到的尾巴和脚掌血管运动的周期性变化。吗啡引起RVM / rMR中记录的细胞内和细胞外放电的突然抑制和激活。通过使用一种模型，该模型考虑了辐射热源的功率，初始皮肤温度，核心体温和周围神经传导距离，可以认为吗啡诱导的反应时间增加主要与吗啡诱导的反应时间有关。血管收缩。通过以心理物理学术语分析对有害辐射热的随机变化的甩尾反应，证实了这一说法。尽管通常以镇痛来解释对辐射热的反应时间的增加，但是本数据质疑使用这种方法建立疼痛指数的有效性。

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