Electrical signal propagated across acupoints along Foot Taiyang Bladder Meridian in rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To investigate the electrical signals propagated along Foot Taiyang Bladder Meridian (BL) in a rat model.</p><p><b>METHODS</b>The experiments were performed on Dark-Agouti (DA), DA.1U and Sprague Dawley (SD) rats. The antidromic electrical stimulation was applied on the nerve innervating "Pishu" (BL 20) to mimic the acupoint electro-acupuncture (EA). The activities recording from adjacent nerve innervating acupoint "Danshu" (BL 19) or "Weishu" (BL 21) were recorded as indics for acupoint, including the mechanical threshold and discharge rate.</p><p><b>RESULTS</b>After mimic EA on BL 20, C and Aδ units from adjacent BL 19 or BL 21 were sensitized including the decrease in mechanical threshold and increase in discharge rates in DA, DA.1U and SD rats, especially in DA rats. The average discharge rate increased from 2.40±0.26 to 6.06±0.55 and from 1.92±0.42 to 6.17±1.10 impulse/min (P<0.01), and the mechanical threshold decreased from 0.52±0.12 to 0.24±0.05 and from 0.27±0.02 to 0.16±0.01 mmol/L (P<0.01) in C (n=15) and Aδ (n=18) units in DA rats. The net change in discharge rates from C units were 152.5%, 144.7% and 42.4% in DA, DA.1U and SD rats, respectively, among which DA rat's was the highest (P<0.05). In Aδ units, the net change in DA rats were also the highest (221.5%, 139.2% and 49.2% in DA, DA.1U and SD rats).</p><p><b>CONCLUSIONS</b>These results showed that mimic acupoint EA activated adjacent acupoints along BL in three rat strains, which might be related to propagated sensation along meridians (PSM). In addition, DA rats were more sensitive and might be a good model animal for PSM research.</p>

Inhibitory effect of octreotide on the cross excitation of adjacent segment of spinal nerve in rat / 生理学报

This study was to observe the effect and possible mechanism of somatostatin analogue octreotide (OCT) on cross excitation of adjacent segment of spinal nerve in rat. Cutaneous branches of T9-T13 spinal dorsal rami were chosen and dissected free for the following recording and stimulation. Only single unit fiber was used for recording, and the adjacent segment of nerve stem was used for antidromic electrical stimulation. To investigate the change of discharge rate and mechanical threshold, OCT and (or) somatostatin receptor antagonist cyclo-somatostatin (c-SOM) were applied to the receptive field following the antidromic electrical stimulation. The result showed that injection of OCT inhibited the increase of discharge rate and the decrease of mechanical threshold induced by the electrical stimulation (cross excitation); c-SOM reversed the effects of OCT. Application of c-SOM alone enhanced the cross excitation effects. The results suggest local application of somatostatin analogue OCT can inhibit the cross excitation between the two segments of spinal nerve by somatostatin receptor.

Dorsal root reflex from Adelta and C afferent fibers induced by electrical stimulation of the sural nerve in rats / 生理学报

The purpose of the study was to investigate whether the small fiber-evoked dorsal root reflex (DRR) can be obtained by electrical stimulation of the peripheral nerve in rats. Fifty-one DRRs were recorded from different kinds of fiber filaments in the proximal ends of the cut L(5) dorsal root following electrical stimulation of the sural nerve. According to the kind of afferent fibers in the sural nerve associated with the DRRs from dorsal root, these DRRs were divided into five different types: A(alphabeta) fiber-evoked A(alphabeta).DRR (A(alphabeta)- A(alphabeta).DRR), A(betadelta) - A(delta ).DRR, A(betadelta)-C.DRR, A(alphabetadelta)-C.DRR and C-C.DRR. The results obtained show that the DRR can be obtained from either A-fibers (including A(delta )-fibers) or C-fibers of dorsal root filaments by stimulation of the sural nerve. It is therefore suggested that either A(delta ).DRR or C.DRR can be used as a validity index of presynaptic inhibition of the thin primary afferent terminals for investigation of the modulation mechanisms of peripheral effectors.

Prostaglandin inhibitor indomethacin inhibits afferent activities of Adelta and C units in the saphenous nerve of diabetic hyperalgesic rats / 生理学报

The effects of a non-selective inhibitor of cyclo-oxygenase (COX) indomethacin, and exogenous prostaglandin E(2) (PGE(2)) on A(delta) units and C units in the saphenous nerve of diabetic hyperalgesic rats were studied. The results showed that the conduction velocity of A(delta) units and C units and their mechanical threshold in diabetic hyperalgesic rats were obviously decreased, and a small number of A(delta) units (4/24) and C units (2/18) produced increased spontaneous activities. Intraperitoneal injection of indomethacin in diabetic hyperalgesic rats significantly relieved mechanical hyperalgesia, and resulted in a decrease in spontaneous afferent activities of the A(delta) units and C units. Subcutaneous injection of exogenous PGE(2) into the diabetic hyperalgesic and control rats produced a significant decrease in mechanical threshold of the A(delta) units and C units, and elicited discharge from 3 A(delta) units (3/24) and 1 C unit (1/18) in diabetic hyperalgesic rats and from 2 A(delta) units (2/13) in control rats. The present data suggest that the synthesis and release of PGs are increased in diabetic neuropathy, PGs can sensitize and /or activate A(delta) units and C units and elicit hyperalgesia and allodynia in diabetic rats.