猫双侧扣带回前部神经元对电刺激内脏大神经的反应

Response of Neurons in the Bilateral Anterior Cingulate Gyrus to Electrically Stimulation of Greater Splanchnic Nerve in Cats

目的 研究猫双侧扣带回前部（ACG）神经元对电刺激内脏大神经（GSN）的反应,为阐明双侧ACG在内脏痛感受中的作用提供实验依据。方法 用在体胞内电位记录技术研究48只猫中791个对侧与312个同侧ACG神经元对电刺激GSN的反应。结果 双侧ACG存有对电刺激GSN产生诱发反应的GSN刺激相关神经元（GSRNs）与不产生诱发反应的非相关神经元。双侧ACG GSRNs分为产生长潜伏期（≥50 ms）GSN诱发反应的内脏伤害感受神经元（VNNs）与产生短潜伏期（〈50 ms）GSN诱发反应的非内脏伤害感受神经元（NVNNs）;VNNs包括只产生长潜伏期GSN诱发反应的特异性VNNs（SVNNs）与既产生长潜伏期GSN诱发反应又产生短潜伏期GSN诱发反应的非特异性VNNs（NSVNNs）两种。GSN伤害性长潜伏期诱发反应阈值为（0.5-0.6）m A;非伤害性短潜伏期诱发反应阈值为（0.3-0.4）m A。双侧ACG VNNs、NVNNs的诱发反应形式相同,包括兴奋性、抑制性及兴奋与抑制或抑制与兴奋混合性反应3类,以兴奋性诱发反应为主。与同侧ACG相比,对侧ACG GSRNs及NSVNNs占观察神经元的比例高（P〈0.01）,而SVNNs占观察神经元的比例低（P〈0.01）。结论 猫双侧ACG神经元对电刺激GSN的反应以兴奋性反应为主。GSN内不同类型的传入神经纤维投射到双侧ACG的不同神经元,但是,以投射到对侧ACG为主;双侧ACG各类神经元所占比例及反应程度不同,为双侧脑的结构和功能不对称性提供新的实验依据。

Objective To study the response of neurons in the bilateral anterior cingulate gyrus （ACG） of cats to electric stimulation of greater splanchnic nerve （ GSN ）, so as to provide experimental data for exploring the bilateral ACG mechanisms of visceral nociceptive sensation. Methods Response of 791 neurons in the contralateral ACG and 312 neurons in the ipsilateral ACG to electrically stimulating GSN in 48 cats were recorded with intracellular recording techniques in vivo. Results There were GSN-stimulus-relative neurons （GSRNs） with evoked responses to electric stimulalion of GSN, and GSN-stimulus-irrelative neurons didn＇t show any GSN evoked response in the bilateral ACG. The GSRNs can be divided in- to visceral nociceptive neurons （VNNs） , which have the long latency （ i〉 50 ms） GSN evoked response, and non- visceral nociceptive neurons （ NVNNs ） with the short latency （ 〈50 ms） GSN evoked response. VNNs, including the specific VNNs （SVNNs） , only showed long latency GSN evoked response, but the non- SVNNs （NSVNNs） showed both long and short latencies GSN evoked response. The threshold intensities for evoking tile long latency noxious response to stimulate GSN in the bilatelnl ACG were （0.5-0.6）mA. Those for evoking the short latency innocuous response to stimulate GSN in the bilateral ACG were （0.3-0.4）mA. The GSN evoked response patterns of both VNNs and NVNNs in the bilateral ACG were the same, which included excitatory response, inhibitory ones, and mixed ones of both excitation and inhibition or inhibition and excitation. The excit- atory evoked response were main observed during these responses. Compared with those in the ipsilateral ACG, the percentages of GSRNs mad NS- VNNs in the contralateral ACG were significantly higher, but the percentage of SVNNs in the contralateral ACG was significantly lower （ P 〈 0.01 ）. Conclusion Our results indicate that the response of neurons in the bilateral ACG of cats to electric stimulation of GSN are mainly excitatory. The afferent fibers of different types of GSN project to different neurons in the bilateral ACG, but mainly to the contalateral ACG. The percentages and reaction degrees of various types of neurons between the bilateral ACG are different, which provides new experimental evidence for asymmetry of structures and functions in the bilateral brain.