Blocking effects of 5-HT_2 receptor antagonist cyproheptadine applied to thalamic nucleus submedius on analgesia produced by high intensity electroacupuncture stimulation in rats
Blocking effects of 5-HT_2 receptor antagonist cyproheptadine applied to thalamic nucleus submedius on analgesia produced by high intensity electroacupuncture stimulation in rats
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发表时间：
2000
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通讯作者：
Xiao Dan
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作者：
Xiao Dan
The analgesic effects produced by high and low intensity electroacupuncture (EA) stimulation of the “Zusanli point” were examined using latency of tail flick (TF) reflex evoked by radiant heat as an index of nociceptive response in the rat lightly anesthetized with pentobarbital. The blocking effects of 5 HT 2 receptor antagonist cyproheptadine (CPT) applied unilaterally to thalamic nucleus submedium (Sm) on both analgesic effects were determined. The results showed that although either high or low intensity EA stimulation could significantly depress the TF reflex, the analgesia produced by high intensity EA (5 mA) was significantly stronger than that obtained from low intensity EA (0.5 mA). Furthermore, CPT (50 ng) microinjection unilaterally into Sm lightly facilitated the TF reflex and effectively antagonized the analgesic effects produced by high intensity EA, but did not influence that produced by low intensity EA, suggesting that the 5 HT and its receptor subtype (5 HT 2 receptor) in Sm may be involved in mediating the analgesia induced by high intensity EA, and may exert a tonic descending inhibitory influence on nociceptive responses. [
