Effects of acupoint versus non-acupoint electroacupuncture on cerebral cortical neuronal Bcl-2, Bax and caspase-3 expression in a rat model of focal cerebral ischemia**☆

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Abstract

BACKGROUND:

Several studies have demonstrated that electroacupuncture by acupoint selection can inhibit cerebral cortical neuronal apoptosis following cerebral ischemia/reperfusion.

OBJECTIVE:

To validate the effects of electroacupuncture by acupoint selection on the expression level of cortical neuronal anti-apoptotic Bcl-2 protein and the apoptotic executive protein, caspase-3, in rat models of focal cerebral ischemia/reperfusion.

DESIGN, TIME AND SETTING:

This randomized grouping, neural cell and molecular biology animal experiment was performed at the Laboratory of Pharmacology of Traditional Chinese Medicine and the Laboratory Animal Center of Henan Institute of Traditional Chinese Medicine between November 2006 and May 2007.

MATERIALS:

Atotal of 40 healthy male adult Sprague-Dawley rats were randomly and evenly divided into four groups: sham-operated, model, electroacupuncture and non-acupoint control. G6895 electro-acupuncture instruments were purchased from Shanghai Huayi Instrument Factory, China. Caspase-3, Bcl-2 and Bax kits were provided by Wuhan Boster Bioengineering Co., Ltd., China.

METHODS:

Middle cerebral artery occlusion was induced in the model, electroacupuncture and non-acupoint groups. In the electroacupuncture group, the acupoints Jianyu (LI15), Waiguan (SJ5), Biguan (ST31), and Zusanli (ST36) were given electroacupuncture. In the non-acupoint control group, at each time point (immediately after ischemia and after reperfusion, or 2 hours after reperfusion), electroacupuncture was performed at the midpoints of Tianquan (PC2)-Quze (PC 3) line, Quze (PC 3)-Ximen (PC4) line, Zuwuli (LR10)-Yinbao (LR9) line, and Xiguan (LR7)-Zhongdu (LR6) line. Electroacupuncture parameters were set with a continuous wave with a frequency of 10 Hz, wave width 0.6 ms, voltage 1.5–3.0 V, and a duration of 10 minutes. The sham-operated and model groups received only animal fixation without electroacupuncture procedure.

MAIN OUTCOME MEASURES:

Five rats were selected from each group for specimen preparation. A brain tissue block comprising the frontal lobe and the occipital lobe was cut into five coronal sections of equal-thickness. Neuronal apoptosis was detected by the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling technique. Expression levels of caspase-3, Bcl-2 and Bax were evaluated by immunohistochemistry.

RESULTS:

Compared with the sham-operated group, the model group exhibited significantly decreased Bcl-2 expression (P < 0.01), and significantly increased Bax protein expression, number of apoptotic cells, and caspase-3 expression (P < 0.01). In the electroacupuncture group, Bcl-2 protein expression was significantly increased (P < 0.01) compared with the model group, and the Bax protein expression, number of apoptotic cells, and caspase-3 expression were significantly decreased (P < 0.01); the above-mentioned changes were not significant in the non-acupoint group compared with the model group (P > 0.05).

CONCLUSION:

Electroacupuncture by acpoint selection can up-regulate Bcl-2 expression and concomitantly inhibit caspase-3 and Bax expression, inhibiting neuronal poptosis in rat cerebral cortex following cerebral ischemia/reperfusion.

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