Effects of acupuncture pre-conditioning on apoptosis in hippocampal neurons following ischemia-reperfusion injury in aged rats

Abstract

To investigate the effects of acupuncture pre-conditioning on apoptosis in hippocampal neurons following ischemia-reperfusion injury in aged rats. A total of 120 senile male Wistar rats aged 19 - 21 months (corresponding to 60-year-old human being) weighting 550 - 710 g were randomly divided into 4 groups (n = 30 each). Cerebral ischemic group: 4-vessel-block was conducted for 4 minutes to establish cerebral ischemic models; Acupuncture pre-conditioning group: electroacupuncture was applied at acupoint Baihui (GV20) with a frequency of 15 Hz and 2 mA for 30 minutes once daily for 5 days. Then the rats received 4-vessel-block for 4 minutes; Sham-operation group: 4 vessels were exposed; Sham-acupuncture group: only electroacupuncture for 5 days without operation. The rats were sacrificed at the end of predetermined duration of reperfusion 12 h, 1, 2, 3 and 7 d respectively. The brains were immediately harvested and hippocampal CA1 region was isolated for (1) light and electron microscopic examinations of hippocampal neurons; (2) detection of apoptotic neurons (TUNEL); (3) determination of caspase-3 protein expression with SABC (streptavidin-biotin-peroxidase complex) immuno-histochemical technique. There were apoptotic neurons in all groups. The numbers of apoptotic neurons and positive neurons of caspase-3 significantly increased in the acupuncture pre-conditioning and cerebral ischemic groups versus the sham-acupuncture and sham-operation groups (P < 0.01). And the numbers of apoptotic neurons and positive neurons of caspase-3 significantly decreased in the acupuncture pre-conditioning group versus the cerebral ischemic group (P < 0.01). Acupuncture pre-conditioning can decrease the neuronal apoptosis after ischemia-reperfusion injury through a lowered expression of caspase-3 protein in senile rats.