OBJECTIVETo investigate the electrical signals propagated along Foot Taiyang Bladder Meridian (BL) in a rat model.

METHODSThe 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.

RESULTSAfter 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).

CONCLUSIONSThese 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.