SPONTANEOUS IMPULSE GENERATION IN NORMAL AND DENERVATED DORSAL-ROOT GANGLIA - SENSITIVITY TO ALPHA-ADRENERGIC STIMULATION AND HYPOXIA
SPONTANEOUS IMPULSE GENERATION IN NORMAL AND DENERVATED DORSAL-ROOT GANGLIA - SENSITIVITY TO ALPHA-ADRENERGIC STIMULATION AND HYPOXIA
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DOI：
10.1016/0014-4886(84)90139-0
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发表时间：
1984-01-01
影响因子：
5.3
通讯作者：
BURCHIEL, KJ
中科院分区：
文献类型：
--
作者：
BURCHIEL, KJ
周围神经损伤后，自发异位冲动产生的两个部位迅速发展：周围神经瘤和背根神经节（DRG）区域。在30只成年Sprague-Dawley大鼠中，从[腰椎] L5背根或近端坐骨神经进行微丝记录。在200个自发活动的离体纤维中观察了异位脉冲发生器的位置、自发放电模式以及对肾上腺素能和缺氧刺激的反应。坐骨神经切断后，神经瘤和背根神经节表现为异位冲动产生的独立来源。起源于神经瘤的自发活动分别对57%和86%的测试纤维的肾上腺素能和缺氧刺激作出反应。自发性活动起源于DRG慢性坐骨神经横断后表现出肾上腺素能刺激的61%的纤维测试，和所有的纤维表现出在缺氧期间的活动增加。在其他正常动物的急性坐骨神经切断术后，可以在少数纤维中记录到起源于DRG的自发活动。同样，48%的这些纤维显示出对局部或全身肾上腺素给药的一些反应，并且缺氧在所有测试的纤维中产生一定程度的激发放电。在正常动物中，给予肾上腺素或低氧刺激均不能使具有完整感受野的DRG神经元兴奋放电。神经瘤和DRG区域的自发活动纤维的肾上腺素能敏感性的药理学表明α-肾上腺素能特异性。一些纤维表现出自发性活动的区域的神经瘤和背根神经节表现出肾上腺素或缺氧敏感性，但不是两者兼而有之。α-受体激动剂和缺氧对这些部位自发放电的主要兴奋作用的机制是不同的。肾上腺素能和/或缺氧反应性是以下神经元的特性：表现出内在自发放电特性的其他正常DRG神经元、表现出自发活动的慢性去神经节中的神经元和神经瘤内的一些纤维。具有完整感受野的正常DRG神经元对缺氧或肾上腺素能刺激的反应似乎不增加其放电率。这些发现可能与周围神经损伤后慢性疼痛的发展有关。
After peripheral nerve lesion, 2 sites of spontaneous ectopic impulse generation rapidly develop: the peripheral neuroma and the region of the dorsal root ganglion (DRG). In 30 adult Sprague-Dawley rats, microfilament recordings were made from either the dorsal root of [lumbar] L5 or the proximal sciatic nerve. The locus of the ectopic impulse generator, spontaneous firing patterns, and response to both adrenergic and hypoxic stimulation were observed in 200 spontaneously active isolated fibers. After sciatic transection the neuroma and the DRG behaved as independent sources of ectopic impulse generation. Spontaneous activity originating in the neuroma was responsive to adrenergic and hypoxic stimulation in 57% and 86% of fibers tested, respectively. Spontaneous activity originating in the DRG after chronic sciatic nerve transection demonstrated a response to adrenergic stimulation in 61% of fibers tested, and all fibers showed an increase in activity during hypoxic periods. After acute sciatic neurotomy in otherwise normal animals, spontaneous activity originating in the DRG could be recorded in a few fibers. Likewise, 48% of those fibers showed some response to topical or systemic epinephrine administration, and hypoxia produced some degree of excitation of firing in all fibers tested. Neither epinephrine administration nor hypoxic challenge produced excitation of firing in DRG neurons with intact receptive fields in normal animals. The pharmacology of adrenergic sensitivity of spontaneously active fibers from both the neuroma and the region of the DRG indicated alpha-adrenergic specificity. A number of fibers exhibiting spontaneous activity from both the region of the neuroma and the DRG showed either adrenergic or hypoxic sensitivity, but not both. The mechanisms of the largely excitatory actions of alpha-agonists and hypoxia on spontaneous discharges from these sites were different. Adrenergic and/or hypoxic responsiveness is a property of: otherwise normal DRG neurons which demonstrate intrinsic spontaneous firing properties, neurons in chronically denervated ganglia which exhibit spontaneous activity and some fibers within neuromas. Normal DRG neurons with intact receptive fields do not appear to increase their firing rate in response to either hypoxia or adrenergic stimulation. These findings may be relevant to the development of chronic pain in man following peripheral nerve injury.