Analysis on Interrelation between Electroacupuncture-lnduced Cumulative Analgesic Effect and Hypothalamic Cholinergic Activities in Chronic Neuropathic Pain Rats

Objective： To observe the effects of repeated electroacupuncture （EA） of Zusanli （ST36）Yanglingquan （GB34） on hypothalamic acetylcholinesterase （AchE） and vesicular acetylcholine （ACh） transporter （VAChT） activities and choline acetyltransferase （CHAT） mRNA and muscarinic M1 receptor （MIR） mRNA expression in chronic constrictive injury （CCI） and/or ovariectomy （OVX） rats so as to reveal its underlying mechanism in cumulative analgesia. Methods： A total of 103 female Wistar rats were randomly divided into normal control （n=15）, CCI （n=15）, CCI＋EA2d （n=15）, CCI＋EA2W （n=15）, OVX＋CCI （n=13）, OVX＋CCI＋EA2d （n=15）, and OVX＋CCI＋EA2W groups （n=15）. CCI model was established by ligature of the unilateral sciatic nerve with surgical suture. Memory impairment model was established by removal of the bilateral ovaries. Morris water test was conducted to evaluate the OVX rats＇ memorylearning ability, and the thermal pain threshold （PT） of the bilateral paws was detected the next morning after EA. EA （2/15 Hz, 1 mA） was applied to bilateral ST36-GB34 for 30 min, once daily for 2 days or 2 weeks, respectively. Hypothalamic AChE activity was detected by histochemistry, VAChT immunoactivity was determined by immunohistochemistry, and ChAT mRNA and MIR mRNA expressions were assayed by reverse transcription-polymerase chain reaction （RT-PCR）. Results： In comparison with the normal control group, the AChE activity in hypothalamic arcuate nucleus （ARC） and supraoptic nucleus （SON） regions of CCI group, AChE activity in paraventricular nucleus （PVN）, ARC, and SON regions of OVX＋CCI group, and hypothalamic muscarinic M1R mRNA expression levels in both CCI and OVX＋CCI groups were down-regulated significantly （P〈0.05）. Compared with the CCI group, the AChE activities in hypothalamic ARC and SON regions of CCI＋EA2d and CCI＋EA2W groups and PVN region of CCI＋EA2W group and hypothalamic ChAT mRNA and M1R mRNA expression levels in CCi＋EA2W group were up-regulated considerably （P〈0.05）. In comparison with the OVX＋CCI group, the AChE activities in PVN, ARC, and SON regions and the expressions of hypothalamic ChAT mRNA and VAChT in ARC region of OVX＋CCI＋EA2W group were up-regulated remarkably （P〈0.05）. The effects in rats of CCI＋EA2W group were evidently superior to those of OVX＋CCI＋EA2d group in up-regulating AChE activities in PVN, ARC, and SON regions, VAChT immunoactivity in ARC region, and expression levels of hypothalamic ChAT mRNA and MIR mRNA （P〈0.05）. Similar situations were found in OVX＋CCI rats after EA2W. It suggested a cumulative effect after repeated EA of ST36-GB34. Comparison between CCI＋EA2W and OVX＋CCI＋EA2W groups showed that the effects in rats of the former group were evidently better than those of the latter group in up-regulating AChE activity in ARC and SON regions and the expressions of hypothalamic ChAT mRNA and M1 mRNA （P〈0.05）, suggesting a reduction of EA2W effects after OVX. Conclusion： Repeated EA can significantlyup-regulate AChE and VAChT activities and ChAT mRNA and MIR mRNA expressions in the hypothalamus of CCI and OVX＋CCI rats, which may contribute to the cumulative analgesic effects of repeated EA and be closely related to the animals＇ neuromemory ability.

Echinacoside Alleviates Cognitive Impairment in Cerebral Ischemia Rats through α7nAChR-Induced Autophagy

Objectives:To evaluate the effect of echinacoside(ECH)on cognitive dysfunction in post cerebral stroke model rats.Methods:The post stroke cognitive impairment rat model was created by occlusion of the transient middle cerebral artery(MCAO).The rats were randomly divided into 3 groups by a random number table:the sham group(sham operation),the MCAO group(received operation for focal cerebral ischemia),and the ECH group(received operation for focal cerebral ischemia and ECH50 mg/kg per day),with 6 rats in each group,The infarct volume and spatial learning were evaluated by triphenyl tetrazolium chloride staining and Morris water maze.The expression of α7 nAChR in the hippocampus was detected by immunohistochemistry.The contents of acetylcholine(ACh),malondialdehyde(MDA),glutathione(GSH),superoxide dismutase(SOD),activities of choline acetyltransferase(ChAT),acetylcholinesterase(AChE),and catalase(CAT)were evaluated by enzyme linked immunosorbent assay.The neural apoptosis and autophagy were determined by TUNEL staining and LC3 staining,respectively.Results:ECH significantly lessened the brain infarct volume and ameliorated neurological deficit in infarct volume and water content(both P<0.01).Compared with MCAO rats,administration of ECH revealed shorter escape latency and long retention time at 7,14 and 28 days(all P<0.01),increased the α7 nAChR protein expression,ACh content,and ChAT activity,and decreased AChE activity in MCAO rats(all P<0.01).ECH significantly decreased MDA content and increased the GSH content,SOD,and CAT activities compared with MCAO rats(all P<0.05).ECH suppressed neuronal apoptosis by reducing TUNEL-positive cells and also enhanced autophagy in MCAO rats(all P<0.01).Conclusion:ECH treatment helped improve cognitive impairment by attenuating neurological damage and enhancing autophagy in MCAO rats.