Impact Of Acupuncture On PKA-CREB Signal Transduction Pathway Of Central Nerve System In Diabetic Ephalopathy Mouse Model

Impact of acupuncture on PKA-CREB signal transduction pathway of central nerve system in diabetic encephalopathy mouse model1 ObjectiveTo study the effects of acupuncture in regulating PKA-CREB signal transduction pathway in mice model with diabetic encephalopathy.2 Method46 adult male Wistar rats were randomly divided into 2 groups. Of which 36 were in study group and the remaining 10 were in placebo group. In study group, rats were tested in the water maze and the avoidance response box 8 days after induction of diabetes. Morrise-water maze test consisted of hidden-platform acquisition training and probe trial testing. The rats were further divided into 4 groups in a random fashion 1)the normal control group NC,2) the diabetic rats with BDNF group,3) the acupuncture group ACP.4) the diabetes group, model group DM. Acupuncture therapy was administered 1 week after confirmed cognition at the beginning of the animal model formation. The prescription of acupuncture points were Baihui(百会)and Dazhui(大椎).The electric acupuncture (2Hz 3 mA) were given to the animals for 20 min, every other day for 20 days.3 ResultsOverview of diabetic animal modelMorrise-water maze testMorris-water maze test is divided into hidden-platform acquisition training and probe trail testing.In hidden-platform acquisition training, escape latency of the diabetes group is longer than the control group, after acupuncture treatment, the escape latency of rats became shorter. After training for seven consecutive days the rats were tested in the water maze without the platform for probe trail testing. Bothe the swimming time and distance in the target quadrant were measured. The swimming time of the rats in model group was significantly shorter than the other groups (P< 0.05) as compared with the control group and acupuncture group). The swimming distance of rats in model group was the shortest among all groups (P< 0.05 as compared with other groups). The above results indicate that the memory in the rats of model group was been efficient, after acupuncture application, the learning and memory capability of the rats has been improved.Immunohistochemistry process:After Morris-water maze test, the brain samples were fixed and collected for histochemical studies. The rats were deeply anesthetized with sodium pentobarbital (40mg/kg body weight) and perfused through heart with the fixatives for 2 hrs. The brain was dissected out and post fixed in the same fixative for 0.5h. Then the tissue were croprotected in 30% concentration of sucrose in 0.1M sodium phosphate buffer at 4℃and sectioned at 40um by frozen section instrument. Eosin (H &E) method for observing morphological changes of the hippocampus and cortex under light microscope. Microscopic observation showed that neuronal loss in the of hippocampus was milder in DM with acupuncture group than that in DM group, these result displayed that in DM rats the cognitive ability declined significantly, acupuncture therapy can amelicorate the learning memory ability in rats with DM. The BDNF, PKAmRNA and CREB expression levels in the hippocampus of DM rats were significantly lower than those of the normal control group (P<0.05). The BDNF, PKAmRNA and CREB expression levels in the hippocampus of the ACP group were significantly higher than those of the DM group (P<0.05).4 Conclusions4.1 In this work, we have demonstrated that acupuncture can significantly increase the expression levels of BDNF in the rat model of diabetic encephalopathy in the hippocampus and cortex regions of the brain. The BDNF positive neurons have distinct phenotype with larger body size, longer and more dendrites which can extend beyond hippocampus region.4.2 Acupuncture can also significantly increase the expression levels of PKA in the rat model of diabetic encephalopathy in the hippocampus and cortex regions of the brain.4.3 Acupuncture can also significantly increase the expression levels of CREB in the rat model of diabetic encephalopathy in the hippocampus and cortex regions of the brain.4.4 Acupuncture can modify PKA-CREB signal transduction pathway which facilitates synthesis and secretion of BDNF, promotes neuronal regeneration and improves subsequent learning and memory capability in the rat model of diabetic encephalopathy.We hypothesize that increased levels of BDNF is likely due to changes in the cascade of PKA-CREB signal transduction pathway which in turn enhances the repairing process of neurons and improves the subsequent learning and memory function. It needs to be noted, however, that our conclusions were made based entirely on the rat model of diabetic encephalopathy which may or may not truly reflective of human situations. Future research is therefore needed to further our understanding of potential underlying mechanism for the observed effect of acupuncture on treating diabetic encephalopathy both in human and in rat.