Neurophysiology Laboratory, Department of Physiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-29, India.
Physiol Behav. 2010 Sep 1;101(2):224-31. doi: 10.1016/j.physbeh.2010.05.002. Epub 2010 May 16.
Sucrose ingestion is reported to produce an initial (20-30min) analgesia and late (<5h) hyperalgesia. However, the influence of the characteristics of noxious stimuli and sweet substances on the pattern of transition from analgesia to hyperalgesia is not known. Therefore, we investigated the effect of sucrose (20%, sucrose fed group), saccharin (0.1%, saccharin fed group) and water ingestion (control group) on pain responses to various noxious stimuli for 5h. Latency of motor response of tail (TFL), paws to noxious thermal stimuli, threshold for elicitation of motor responses to electrical stimulation of tail nociceptive afferents in 5 sessions (0, 0.25, 1, 3 and 5h) and pain-related behavior to tonic noxious stimulus in 3 sessions at 1, 3 and 5h were recorded. In sucrose fed rats as compared to controls, the TFL sequentially increased (9.29+/-0.47s from 8.41+/-0.25; p<0.01), recovered to base-line and decreased (6.61+/-0.61sec; p<0.0001) in sessions II, III and V indicating analgesia, eualgesia and hyperalgesia, respectively. In saccharin fed rats the initial analgesia extended until session III followed by eualgesia and hyperalgesia in sessions IV and V. Pain related behaviour to tonic noxious stimulus also indicated an initial analgesia (0-5min), intermediate eualgesia and late hyperalgesia (3-5h) in sucrose fed rats, whereas only analgesia in saccharin fed rats. The results of our study suggest that sucrose ingestion for 5h leads to a bi-phasic response to both phasic and tonic noxious stimuli, albeit there are variations in their durations. Therefore, the temporal relationship of the nociceptive responses to palatable food is a function of the stimulus quality of both.
蔗糖摄入据报道会产生初始（20-30 分钟）镇痛和后期（<5 小时）痛觉过敏。然而，尚不清楚有害刺激物和甜味物质的特征对从镇痛向痛觉过敏转变模式的影响。因此，我们研究了蔗糖（20%，蔗糖喂养组）、糖精（0.1%，糖精喂养组）和水摄入（对照组）对 5 小时内各种有害刺激引起的疼痛反应的影响。在 5 个时间段（0、0.25、1、3 和 5 小时）内记录了尾部（TFL）运动反应潜伏期、爪子对有害热刺激的反应阈值、尾部伤害性传入纤维电刺激诱发运动反应的阈值，以及 1、3 和 5 小时时 3 个时间段内的持续有害刺激的疼痛相关行为。与对照组相比，蔗糖喂养大鼠的 TFL 依次增加（从 8.41±0.25 增加到 9.29±0.47s；p<0.01），在第 II、III 和 V 时段恢复到基线并减少（6.61±0.61sec；p<0.0001），分别表示镇痛、等痛和痛觉过敏。在糖精喂养的大鼠中，初始镇痛持续到第 III 时段，随后在第 IV 和 V 时段出现等痛和痛觉过敏。蔗糖喂养大鼠的持续有害刺激相关行为也表明存在初始镇痛（0-5 分钟）、中间等痛和晚期痛觉过敏（3-5 小时），而糖精喂养大鼠则只有镇痛。我们的研究结果表明，蔗糖摄入 5 小时会导致对相性和持续有害刺激产生双相反应，尽管它们的持续时间存在差异。因此，对美味食物的伤害性反应的时间关系是两者刺激质量的函数。
