Effects of Danggui-Shaoyao-San on the Influence of Spatial Learning and Memory Induced by Experimental Tooth Movement

Background： The pain caused by orthodontic treatment has been considered as tough problems in orthodontic practice. There is substantial literature on pain which has exactly effected on learning and memory; orthodontic tooth movement affected the emotional status has been showed positive outcomes. Danggui-Shaoyao-San （DSS） is a Traditional Chinese Medicine prescription that has been used for pain treatment and analgesic effect for orthodontic pain via inhibiting the activations of neuron and glia. We raised the hypothesis that DSS could restore the impaired abilities of spatial learning and memory via regulating neuron or glia expression in the hippocampus. Methods： A total of 36 rats were randornly divided into three groups： （ 1 ） Sham group （n = 12）, rats underwent all the operation procedure except for the placement of orthodontic forces and received saline treatment： （2） experimental tooth movement （ETM） group （n - 12）, rats received saline treatment and ETM： （3） DSS ＋ ETM （DETM） group （n = 12）, rats received DSS treatment and ETM. All DETM group animals were administered with DSS at a dose of 150 mg/kg. Monis water maze test was evaluated： immunofluorescent histochemistry was used to identity astrocytes activation, and immunofluorescent dendritic spine analysis was used to identify the dendritic spines morphological characteristics expression levels in hippocampus. Results： Maze training sessions during the 5 successive days revealed that ETM significantly deficits in progressive learning in rats, DSS that was given from day 5 prior to ETM enhanced progressive learning. The ETM group rats took longer to cross target quadrant during the probe trial and got less times to cross-platform than DETM group. The spine density in hippocampus in ETM group was significantly decreased cornpared to the sham group. In addition, thin and mature spine density were decreased too. However, the DSS administration could reverse the dendritic shrinkage and increase the spine density compared to the ETM group. Astrocytes activation showed the opposite trend in hippocampus dentate gyrus （DG）. Conclusions： Treatment with DSS could restore the impaired abilities on ETM-induced decrease of learning and memory behavior. The decreased spines density in the hippocampus and astrocytes activation in DG ofhippocampus in the ETM group rats may be related with the decline of the ability of learning and rnernory. The ability to change the synaptic plasticity in hippocarnpus after DSS administration may be correlated with the alleviation of impairment of learn and memory atter ETM treatment.

Danggui-shaoyao-san, a traditional Chinese medicine prescription, alleviates the orthodontic pain and inhibits neuronal and microglia activation

Background The pain caused by orthodontic treatment has been considered as tough problems in orthodontic practice. Danggui-shaoyao-san （DSS） is a traditional Chinese medicine （TCM） prescription which has long been used for pain treatment and possesses antioxidative, cognitive enhancing and antidepressant effects. We raise the hypothesis that DSS exerts analgesic effect for orthodontic pain via inhibiting the activations of neuron and microglia. Methods DSS was given twice a day from day 5 prior to experimental tooth movement （ETM）. Directed face grooming and vacuous chewing movements （VCM） were evaluated. Immunofiuorescent histochemistry and Western blot analysis were used to quantify the Iba-1 （microglia activation） and Fos （neuronal activation） expression levels in the trigeminal spinal nucleus caudalis （Vc）. Results ETM significantly increased directed face grooming and VCM which reached the peak at post-operative day （POD） 1 and gradually decreased to the baseline at POD 7. However, a drastic peak increase of Fos expression in Vc was observed at 4 hours and gradually decreased to baseline at POD 7; while the increased Iba-1 level reached the peak at POD 1 and gradually decreased to baseline at POD 7. Furthermore, pre-treatment with DSS significantly attenuated the ETM induced directed face grooming and VCM as well as the Fos and Iba-1 levels at POD 1. Conclusion Treatment with DSS had significant analgesic effects on ETM-induced pain, which was accompanied with inhibition of both neuronal and microglial activation.