Electroacupuncture improves learning and memory function and promotes hippocampal synaptic regeneration in rats with cerebral ischemia-reperfusion injury

doi:10.12122/j.issn.1673-4254.2024.12.07

Abstract

Abstract:

Objective To explore the neuroprotective mechanism of electroacupuncture at the acupoints Baihui and Shenting in rats with cerebral ischemia-reperfusion (IR) injury. Methods Forty-eight male SD rats were equally randomized into sham operation group, cerebral IR model group, acupoint electroacupuncture group and non-acupoint acupuncture group. In the latter 3 groups, cerebral focal ischemic injury was induced using the Longa method; in the two electroacupuncture groups, electroacupuncture was performed either at the acupoints Baihui and Shenting or at non-acupoint sites for 7 days. The changes in neurological deficit scores, cerebral infarction volume, learning and memory function, pathologies in hippocampal CA1 area, neuronal and synaptic ultrastructures, and synaptic density of the rats were observed, and serum GABA level and mRNA and protein expressions of GABA_AR α1, CaMK II, SYN1 and PSD-95 in the hippocampal tissue were detected. Results Compared with those in cerebral IR model group, the rats receiving electroacupuncture at the acupoints, but not those with electroacupuncture at the non-acupoints, showed significantly decreased neurological deficit scores and cerebral infarction volume with shortened escape latency and increased platform crossings. Electroacupuncture at the acupoints significantly increased neuronal cell number, decreased the width of the synaptic gaps and increased density of synaptic bodies in the ischemic hippocampal CA1 area, resulting also in increased serum GABA levels and hippocampal expressions of GABA_ARα1, SYN1 and PSD-95 and lowered expression level of CaMK II. Conclusion Electroacupuncture at Baihui and Shenting improves learning and memory function of rats with cerebral IR injury possibly through a mechanism that promotes synaptic regeneration, upregulates hippocampal expressions of GABAAR α 1, SYN1 and PSD-95 and downregulates the expression of CaMK II.

Key words: cerebral ischemia-reperfusion injury, electroacupuncture, learning and memory function, synaptic regeneration, synaptic plasticity

Ruhui LIN, Jinyan XIA, Xiaohan MA, Zuanfang LI. Electroacupuncture improves learning and memory function and promotes hippocampal synaptic regeneration in rats with cerebral ischemia-reperfusion injury[J]. Journal of Southern Medical University, 2024, 44(12): 2317-2326.

Figures/Tables 10

Tab.1 Primer sequences for RT-qPCR

Gene	Primer sequences 5'-3'	Amplified size (bp)
GABA_ARα1	F: TGTCTTTGGAGTGACGACCG	187
GABA_ARα1	R: ATCCCACGCATACCCTCTCT
CaMKⅡ	F: AAGATGTGCGACCCTGGAAT	178
CaMKⅡ	R: ACTGAGTGATGCGGATGTAGG
SYN1	F: GGTGGATTCTCCGTGGACAT	142
SYN1	R: GCAGCCCAATGACCAAACTG
PSD-95	F: CAGTGAGACCGACGACATTG	199
PSD-95	R: GATGATGGGACGAGCATAGTG
GADPH	F: ACGGCAAGTTCAACGGCACAG	149
GADPH	R: AAGACGCCAGTAGACTCCACGAC

Fig.1 Comparison of Zea-Longa neurological function scores among the 4 groups before and after the treatment. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group. EA: Electroacupuncture at acupoints; NA: Electroacupuncture at non-acupoints.

Fig.2 Comparison of T2WI and cerebral infarction volume among the 4 groups before and after the treatment. A: T2WI before and after intervention. Red area indicates cerebral infarction. B: Comparison of cerebral infarction volume.*P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.3 Comparison of escape latency (A) and number of platform crossings (B) among the 4 groups. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.4 HE staining of the hippocampal CA1 region (Scale bar=50 μm). Arrows indicate the destroyed structure.

Fig.5 Transmission electron microscopy of the synaptic structure and synapsis number in the hippocampal CA1 region on the ischemic side. A: Synaptic ultrastructure of hippocampal CA1 region. Arrows indicate the changed synaptic vesicle. B: Synapsis number in the hippocampal CA1 region on the ischemic side. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.6 Comparison of serum GABA levels among the 4 groups. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.7 Comparison of relative expressions of GABAAR1, CaMK II, SYN1 and PSD-95 mRNA in the hippocampus on the ischemic side. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.8 Comparison of GABAAR1 (A), CaMK II (B), SYN1 (C) and PSD-95 protein (D) expressions in the hippocampus on the ischemic side detected by Western blotting. *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

Fig.9 Immunofluorescence staining for SYN1 (A) and PSD-95 (B) in the CA1 region of the ischemic hippocampus in the 4 groups (Scale bar=50 μm). *P<0.05 vs Sham group; #P<0.05 vs MCAO/R group; △P<0.05 vs EA group.

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