Changes in response properties and receptive fields of spinal dorsal horn neurons in rats after surgical incision in hairy skin
Changes in response properties and receptive fields of spinal dorsal horn neurons in rats after surgical incision in hairy skin
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DOI：
10.1097/00000542-200501000-00023
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发表时间：
2005-01-01
期刊：
影响因子：
8.8
通讯作者：
Collins, JG
中科院分区：
文献类型：
--
作者：
Kawamata, M;Koshizaki, M;Collins, JG
背景：与化学刺激物应用相关的机械性痛觉过敏和痛觉异常是由脊髓高阈值(HT)和“中枢敏化”所致的大动态范围神经元介导的。由于疼痛的病理生理学根据损伤类型的不同而不同，在有毛皮肤和无毛皮肤之间可能存在差异，作者观察了手术切开大鼠有毛皮肤后脊髓背角神经元特性的变化，以深入了解术后疼痛的机制。方法：在后腿经有毛皮肤、筋膜和肌肉进行1 cm纵向切开后，测定清醒大鼠对点状机械刺激和轻柔刷牙的撤退反应，观察邻近损伤部位的区域(初级区域)和距离损伤部位2 cm的区域(次级区域)的撤退反应。在另一项单独的研究中，记录了脊髓宽动态范围神经元、羟色胺神经元和低阈值神经元在其感受野中心进行类似切开之前和之后对非伤害性和伤害性刺激的反应。结果：清醒大鼠在切开后30min、4d和1d分别表现出原发和继发性痛敏，表现为点状机械刺激。与毛刷刺激相关的机械性异位痛仅在切开后30min出现在原发区，此后持续1d。切开导致大动态范围神经元的活动增加(感受野大小以及对无害和有害刺激的反应)。切开后，HT神经元对无害性刺激无反应，感受野大小和对伤害性刺激的反应轻微增加或无变化。结论：尽管大剂量荷包牡丹碱(15µg/50µl)能逆转γ-氨基丁酸介导的抑制作用，但大动态范围的神经元可能与手术切开后的行为高兴奋性有关，但与高兴奋性无关。
Background: Mechanical hyperalgesia and allodynia associated with chemical irritant application are mediated by spinal high-threshold (HT) as well as wide-dynamic-range neurons as a result of "central sensitization." Because the pathophysiology of pain is thought to differ depending on the type of injury and may vary between hairy and glabrous skin, the authors examined changes in properties of spinal dorsal horn neurons after surgical incisions in hairy skin of rats to obtain insights into the mechanisms of postoperative pain.Methods: Withdrawal responses to punctate mechanical stimulation and gentle brushing were measured in awake rats In an area adjacent to the injured site (primary area) and in an area 2 cm from the injured site (secondary area) after 1-cm longitudinal incisions through the hairy skin, fascia, and muscle had been made in the hindquarters. In a separate study, responses of spinal wide-dynamic-range, HT, and low-threshold neurons to nonnoxious and noxious stimuli were recorded before and after similar incisions had been made in the centers of their receptive fields. Effects of spinal application of the gamma-aminobutyric acid A receptor antagonist bicuculline (15 mug) on responses of HT neurons were then studied.Results: Awake rats showed primary and secondary hyperalgesia to punctate mechanical stimulation 30 min after the incision and thereafter for 4 days and 1 day, respectively. Mechanical allodynia associated with brush stimulation was only seen in the primary area 30 min after the incision and thereafter for 1 day. The incision resulted in increases in activity of wide-dynamic-range neurons (receptive field sizes and responses to both innocuous and noxious stimuli). HT neurons did not respond to innocuous stimulation and showed very small increases or no changes in receptive field size and responses to noxious stimuli after the incision. However, the majority of HT neurons began to respond to innocuous stimuli after application of bicuculline (15 mug/50 mul) to the spinal cord.Conclusions: The results suggest that wide-dynamic-range neurons are responsible for behavioral hyperexcitability after surgical incision but that HT neurons are not involved in the hyperexcitability, despite the fact that HT neurons arc capable of responding to innocuous stimuli by reversal of gamma-aminobutyric acid-mediated inhibition.