"Intensity-response" effects of electroacupuncture on gastric motility and its underlying peripheral neural mechanism.

The aim of this study was to explore the "intensity-response" relationship between EAS and the effect of gastric motility of rats and its underlying peripheral neural mechanism by employing ASIC3 knockout (ASIC3-/-), TRPV1 knockout (TRPV1-/-), and C57BL/6 mice. For adult male Sprague-Dawley (n = 18) rats, the intensities of EAS were 0.5, 1, 3, 5, 7, and 9 mA, respectively. For mice (n = 8 in each group), only 1 mA was used, by which C fiber of the mice can be activated. Gastric antrum motility was measured by intrapyloric balloon. Gastric motility was facilitated by EAS at ST36 and inhibited by EAS at CV12. The half maximal facilitation intensity of EAS at ST36 was 2.1-2.3 mA, and the half maximal inhibitory intensity of EAS at CV12 was 2.8 mA. In comparison with C57BL/6 mice, the facilitatory effect of ST36 and inhibitive effect of CV12 in ASIC3-/- mice decreased, but the difference was not statistically significant (P > 0.05). However, these effects in TRPV1-/- mice decreased significantly (P < 0.001). The results indicated that there existed an "intensity-response" relationship between EAS and the effect of gastric motility. TRPV1 receptor was involved in the regulation of gastric motility of EAS.

[Effects of electroacupuncture and regional thermal stimulation at "Zusanli" (ST 36) on pain thresholds of TRPV 1 knock-out mice].

OBJECTIVE: To observe the effect of electroacupuncture (EA) and moxibustion-like thermal stimulation with different temperatures at "Zusanli" (ST 36) on pain reactions in transient receptor potential vanilloid type 1 knock-out (TRPV 1 -/-) mice so as to study its mechanisms underlying analgesia. METHODS: Ten C 57 BL/6 mice and 10 TRPV 1 -/- mice were respectively divided into control and TRPV 1 -/- groups. EA (0.3 mA, 1.0 mA, 3.0 mA) or thermal water-bath (38 degrees C, 43 degrees C, 46 degrees C) stimulation was applied to the right ST 36 for 20 min and 10 min, respectively. Mechanical and thermal pain thresholds of the bilateral paws were detected before and immediately after stimulation, and 5 min after EA stimulation at 0.3 mA, 3.0 mA and thermal water-bath stimulation at 38 degrees C, 46 degrees C, separately. RESULTS: (1) The thermal threshold was significantly higher in TRPV 1 -/- mice than in C 57 BL/6 mice (P < 0.001). (2) In C 57 BL/6 mice, both homolateral and contralateral mechanical and thermal pain thresholds were significantly increased following 1.0 mA, 3.0 mA EA, and 43 degrees C and 46 degrees C thermal stimulation of the right Zusanli (ST 36) (P < 0.05, P < 0.01, P < 0.001); while only homolateral mechanical and thermal pain thresholds were increased after 0.3 mA EA and 38 degrees C thermal stimulation of ST36 (P < 0.05, P < 0.01). In TRPV 1 -/- mice group, both homolateral and contralateral mechanical and thermal pain thresholds were significantly increased by 3.0 mA EA stimulation of ST 36 (P < 0.05, P < 0.01). Bilateral mechanical thresholds and homolateral thermal threshold were significantly increased by 1.0 mA EA stimulation of ST 36 (P < 0.05, P < 0.01), while only homolateral mechanical and thermal pain thresholds were increased by 0.3 mA EA, and 43 degrees C and 46 degrees C thermal stimulation (P < 0.05, P < 0.01). Additionally, only the homolateral mechanical threshold was increased by 38 degrees C thermal stimulation (P < 0.05). (3) The mechanical and thermal pain thresholds of the bilateral limbs were increased to some extent in TRPV 1 -/- mice compared with those of C 57 BL/6 mice following EA and thermal stimulation of the right ST 36. (4) Five minutes after 0.3 mA, 3.0 mA EA and 38 degrees C, 46 degrees C thermal water-bath stimulation, both mechanical and thermal pain thresholds recovered to their baseline levels in both TRPV 1 -/- and C 57 BL/6 mice. CONCLUSION: Both EA and thermal stimulation of the right ST 36 can raise mechanical and thermal pain thresholds in TRPV 1 -/- and C 57 BL/6 mice, but needing a stronger stimulation in TRPV 1 -/- mice, suggesting an involvement of TRPV 1 receptors in analgesia.

[Effects of transcutaneous electrostimulation of auricular concha at different stimulating frequencies and duration on acute seizures in epilepsy rats].

OBJECTIVE: To observe the inhibitory effect of auricular concha transcutaneous electrostimulation (ACTES) of different frequencies and duration on acute seizures in epilepsy rats so as to select a better stimulating parameter for relieving epilepsy. METHODS: According to the stimulation duration of ACTES, 44 Sprague-Dawley rats were randomized into: 30 s, 5 min, 10 min, and 30 min groups. Epilepsy model was duplicated by intraperitoneal injection of PTZ (pentylenetetrazol, 50 mg/kg). Cerebral field potentials delivered from the fixed 4 recording electrodes array (A-P: -3 -6, L: 4 - 6, H: 1. 5) and reference electrode (a fixed screw) touching the cerebral dura surface were recorded using a data acquisition system (Cerebus 5.0 system). Transcutaneous electrostimulation (1 mA, duration 500 micro(s)) of frequency 2 Hz, 20 Hz and 100 Hz was applied to auricular concha by using an electric stimulator. The anti-epileptic effects of ACTES were evaluated by using the duration and rate of seizure suppression. RESULTS: (1) The anti-epileptic effect of 20 Hz -ACTES was markedly longer than those of 2 Hz and 100 Hz in the duration of seizure suppression (P < 0.05). (2) After 2 Hz-ACTES, the anti-epileptic effects (duration and inhibitory rate) in 30 s-stimulation group were markedly longer than those of the 5 min-, 10 min- and 30 min-stimulation groups (P < 0.01, P < 0.05). (3) After 100 Hz-ACTES, the anti-epileptic effects (duration and rate of seizure suppression) in the 30 min-stimulation group were markedly longer than those in the 30 s-, 5 min- and 10 min-stimulation group (P < 0.01, P < 0.05). CONCLUSION: ACTES at 20 Hz can effectively lessen epileptic seizures, and under fixed stimulating frequencies of 2 Hz and 100 Hz, the anti-epileptic effects of 30 s ACTES and 30 min-ACTES are obviously better in epilepsy rats.

[Effect of electroacupuncture on cortical spreading depression and plasma CGRP and substance P contents in migraine rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on cortical spreading depression (CSD) and contents of plasma calcitonin gene-related peptide (CGRP) and substance P (SP) in migraine rats. METHODS: Thirty male SD rats were equally randomized into control, model and EA groups. Migraine model was established by topical application of KCI (3 mol/L) immersed in a piece of filter paper to the cerebral cortex (parietal lobe, 6 mm posterior to the Bregma and 5 mm to the sagital fissure) after exposure of the skull (in reference to Michael' method). KCI stimulation evoked CSD potentials (3 mm rostral to the Bregma, and 2 mm to the sagital fissure) were recorded by using a glass microelectrode. For rats of control group, filter paper containing 0.9% NaCl was applied to the same parietal cortex area. EA (1 mA, 2 Hz/100 Hz) was applied to bilateral "Yanglingquan" (GB 34) and "Taichong" (LR 3) for 30 min. The contents of plasma CGRP and SP were assayed by radioimmunoassay. RESULTS: CSD was induced 3-5 min after application of KCI to the parietal lobe. The average amplitude of model group was (-25.13 +/- 1.23) mV, and that of EA group was (-19.19 +/- 1.53) mV, displaying a significant reduction of CSD amplitude after EA (P < 0.01). Comparison among 3 groups showed that both plasma CGRP and SP contents in model group were significantly higher than those of control group (P < 0.001, P < 0.01), while compared with model group, plasma CGRP and SP levels in EA group decreased considerably (P < 0.05, P < 0.001), suggesting an inhibitory effect of EA on pain-producing substance. CONCLUSION: EA of GB 34 and LR 3 can effectively suppress KCI provoked cortical spreading depression and plasma CGRP and SP levels in the rat, which may contribute to its effect in relieving migraine in clinic.