Abstract.A previous study by our group found that electro-acupuncture (EA) at the Shenting (DU24) and Baihui (DU20) acupoints ameliorates cognitive impairment in rats with cerebral ischemia-reperfusion (I/R) injury. However, the precise mechanism of action has remained largely unknown. The present study investigated whether brain-derived neurotropic factor (BDNF) mediates hippocampal synaptic plasticity as the underlying mechanism. Rats were randomly divided into three groups: The sham operation control (Sham) group, the focal cerebral ischemia-reperfusion (I/R) group, and the I/R with EA treatment (I/R+EA) group. The I/R+EA group received EA treatment at the Shenting (DU24) and Baihui (DU20) acupoints after the operation. EA treatment was found to ameliorate neurological deficits (P<0.05) and reduce the cerebral infarct volume (P<0.01). In addition, EA improved cognitive function in cerebral I/R-injured rats (P<0.05). Furthermore, EA treatment promoted synaptic plasticity. Simultaneously, EA increased the hippocampal expression of BDNF, its high-affinity tropomyosin receptor kinase B (TrkB) and post-synaptic density protein-95 (PSD-95) in the rats with cerebral I/R injury. Collectively, the findings suggested that BDNF-mediated hippocampal synaptic plasticity may be one mechanism via which EA treatment at the Shenting (DU24) and Baihui (DU20) acupoints improves cognitive function in cerebral I/R injured rats.
IntroductionIn 2011, an estimated 795,000 individuals experienced a stroke event in the United States of America (1). Stroke is one of the most common causes of cognitive impairment (2-4). According to different subtypes and diagnostic criteria of stroke, 17-92% of patients present with cognitive impairment 3 months after a stroke (5). Cognitive impairment can cause a variety of symptoms, such as a decline in attention, memory and problem-solving capability (6); therefore, prevention and treatment of stroke with cognitive impairment has become a priority in the global health sector.Acupuncture at the Shenting (DU24) and Baihui (DU20) acupoints has been used in China to treat cognitive impairment for thousands of years. They are located on a branch of the Du Meridian that runs over the head, which are associated with cognitive function in Traditional Chinese Medicine. Previous studies by our group have confirmed the efficacy of electro-acupuncture (EA) on the Shenting (DU24) and Baihui (DU20) acupoints in the rehabilitation of cognitive impairment in experimental settings (7,8).Although the pathogenic mechanisms of post-stoke cognitive impairment are complex, decreased hippocampal synaptic plasticity has been suggested to be one of the key elements (9,10). Modulation of synaptic plasticity is highly controlled by brain-derived neurotropic factor (BDNF) protein binding to specific tropomyosin receptor kinase B (TrkB) Electro-acupuncture ameliorates cognitive impairment via improvement of brain-derived neurotropic factor-mediated hippocampal synaptic plasticity in cerebral ischemia-reperfusion injured rats