Effect Of Electroacupuncture Pretreatment On +Gz-induced Impairment Of Learning And Memory In Rats And Its Mechanisms

Experiment 1: +Gz exposure induces impairment of learning and memory in ratsObjective: Sustained +Gz exposure could significantly reduce cerebral blood flow, result in transient cerebral ischemia and induce loss of consciousness (G-LOC). Several animal experiments have demonstrated that high sustained +Gz exposure could transiently decrease locomotor's activity, impair learning ability, and induce a deficit in memory retention in rats. In this experiment, we test whether +10Gz/5min exposure could induce cognitive impairment in rats.Methods: Sixteen male SD rats were randomly assigned to 2 groups (n=8): Sham group and +Gz exposure group (+Gz). At 2h after the exposure, rats were assessed with Morris water maze. In the spatial learning test and the probe test, the Escape Latency, Pathlength to the platform, Swimming Speed, Percentage of target quadrant and Number of crossing the platform were recorded.Results: In the spatial acquisition test, rats in +Gz group have a longer Escape Latency and Pathlength to the platform compared with Sham group[F (1, 14) = 4.98, P<0.01],[F (1, 14) = 5.93, P<0.01],and there are no different in the Swimming Speed [F (1, 14) = 1.95, P>0.05 ]. In the probe trial test, the percentage of target quadrant and the number of crossing the platform are significantly decreased in +Gz group in comparison to Sham group(44.15±2.35 V 27.45±1.65, P < 0.01), (4.25±0.67 V 1.73±0.75, P < 0.01).Conclusions: +10Gz/5min exposure could cause impairment of learning and memory in rats.Experiment 2: Electroacupuncture pretreatment ameliorates +Gz-induced impairment of learning and memory in ratsObjective: To investigate whether EA pretreatment (EA-PT) could ameliorate +Gz-induced impairment of learning and memory in rats.Methods: Forty male SD rats were randomly assigned to 5 groups (n=8): Sham group, control (Con) group, electroacupuncture (EA) group, +Gz exposure group (+Gz) and EA plus electroacupuncture (EA-+Gz) group. All the animals were anesthetized with intraperitoneal injection of 40 mg/kg pentobarbital sodium once a day for 5 consecutive days except those in Sham group and +Gz group; Sham group was given +1Gz/5min exposure; EA group was given BaiHui"stimulation with the intensity of 1 mA and frequency of 2/15 Hz for 30 min for five consecutively days; Con and +Gz group were given +10Gz/5min exposure; EA-+Gz group was given EA-PT first, then suffered +10Gz/5min exposure. All the rats were tested with Morris water maze 2h after the exposure, and the data were recorded automatically.Results:①In the spatial acquisition test, the overall data of the Escape Latency and the Pathlength to the platform have significant different[F (4, 35) = 5.98, P<0.01],[F (4, 35) = 6.32, P <0.01]. The Sham, EA group have no different. Compared with the two group above, +Gz group and Con group have a longer Escape Latency and the Pathlength to the platform (P<0.05). EA-+Gz group's are shorter than +Gz group's , but are longer than Sham group; there is no significant different in Swimming peed among these five groups[F (4, 35) = 1.65, P >0.05 ].②In the probe trial test, the Percentage of target quadrant and the Number of crossing the platform are significantly decreased (P <0.05) in +Gz group in comparison to the Sham group(45.35±2.35 V 27.25±1.35, P < 0.01). The Percentage of target quadrants and the Number of crossing the platform significantly increase in EA-+Gz group compared with those in +Gz group (P <0.05).Conclusions: EA-PT could ameliorate +Gz induced impairments of learning and memory in rats.Experiment 3: Electroacupuncture pretreatment inhibits +Gz exposure-induced neuronal apoptosis in hippocampus of CA1 region in ratsObjective: To assess whether EA pretreatment decrease neuronal apoptosis in hippocampus of CA1 region in rats.Methods: Forty-five male SD rats were randomly assigned to 3 groups (n=15): Sham group, +Gz exposure group (+Gz) and EA plus electroacupuncture (EA-+Gz) group. Sham group was given +1Gz/5min; +Gz group was given +10Gz/5min; EA-+Gz group was given EA pretreatment with the intensity of 1 mA and frequency of 2/15 Hz for 30 min for five consecutively days first, then suffered +10Gz/5min. At 6h,12h,24h after +Gz exposure, the histopathology was assessed by HE staining, and the hippocampus CA1 apoptotic pyramidal neuronal cells were evaluated by TUNEL staining and Caspase-3 activity, and the expression of P53 mRNA and protein by using RT-PCR and Western Blotting.Results: We find that in the early stage of +Gz exposure(6-12h), the neuron in hippocampus CA1 region mainly appear edema, and no obvious injured neurons are observed at 6 h after +Gz exposure. At 24 h after +Gz exposure, the total intact cell count of CA1 region is significantly decreased and apoptosis cells increase, but EA pretreatment could decrease the apoptosis cell in CA1 region. Moreover, +10Gz/5min could induce increasing of Caspase-3 activity, significant in 6h after exposure, and last to 12h. The expression of P53 mRNA and protein were increased after exposure, and EA pretreatment could decrease this elevation.Conclusions: EA pretreatment could significant dicrease pathological lesion of hippocampus CA1 region, and decrease the apoptosis cells, Caspase-3 activity, and increase the expression of P53 mRNA and protein.Experiment 4: Effect of Electroacupuncture pretreatment on the expression of Neuroglobin in rats exposed to +GzObjective: To evaluate effect of electroacupuncture pretreatment on the expression of Neuroglobin in rats exposed to +Gz.Methods: Fifteen male SD rats were randomly assigned to 3 groups(n=5): Sham group, +Gz exposure group(+Gz) and EA plus electroacupuncture (EA-+Gz) group. Sham group was given +1Gz/5min exposure; +Gz group was given +10Gz/5min exposure; EA-+Gz group was given EA pretreatment with the intensity of 1 mA and frequency of 2/15 Hz for 30 min for five consecutively days first, then suffered +10Gz/5min exposure. All rats were sacrificed at 24h after the exposure. Using the immunohistochemistry, immunofluorescence, and Western Blotting, the distribution and expression of NgB protein after the +Gz exposure were investigated.Results: At 24h after +Gz exposure, NgB protein expression increased in cortex, and decreased in hippocampus. EA pretreatment could further increase the elevation of NgB in cortex, and have no influence on that in hippocampus. Conclusions: +Gz exposure could increase the expression of NgB protein in cortex, and +EA pretreatment could further increase this elevation, suggesting that up-regulate of NgB involved in EA pretreatment.