| The pathogenic mechanism of depression has not been known, though there are many hypotheses, such as the monoamine hypothesis, the neuroendocrine hypothesis, the immune imbalance hypothesis and so on, even if each of them may explain the occurrence of depression in different ways, none of them can inllustrate the mechanism thoroughly. The latest theory suggests that the neurons in hippocampus may contribute to depression, antidepressive treatment could increase neurogenesis, and the up-regulating of hippocampal neurogenesis might reverse or prevent the damage of stress on the brain, especially on the hippocampal structure and function. Neurogenesis undoubly provides us a new view in treating depression, a neurodegenerative disease.Nardostachys chinensis Batal, with a function of regulat ing Qi to alleviate pain and opening stagnation to refresh Pi, exhibited sedative, antidepressive and promoting neurogenesis effect in modern researches.Nardosinone, one of the active ingredients extracted from Nardostachys chinensis Batal, showed an antidepressive activity in the pre-experiments.In our study, the effect of Nardosinone on the central nervous system in vivo and on neurogenesis in vitro, and the possible mechanisms of antidepressant effect were investigated.1. The Effect of Nardosinone on the central nervous systemThe aim of this part of study is to observe the effect of Nardosinone on the central nervous system, to discuss whether nardosinone has an ant idepressant effect preliminarily. Acute toxicity test was carried out firstly to determine the appropriate dose, and then observed the effect on autonomous activity and synergies by subthreshold dose of sodium pentobarbital, and then observed immobility time in tail suspension test and forced-swim test in mice. The acute toxicity test result showed that the maximum dose of Nardosinone is 8.07 g. kg-1. The spontaneous activity test showed that Nardosinone could not decrease spontaneous activity in mice significantly when compared with the control group (P<0.05). The research of subthreshold dose of pentobarbital sodium induced sleep showed that there was no significant difference between the Nardosinone group and the control group, but showed some increasing trends in positive rate. In the tail suspension test and forced-swim test Nardosinone 0.800 g. kg-1 0.267 g. kg-1,0.160 g. kg-1 decreased the immobility time significantly when compared with the control group (P<0.01). The results suggest that Nardosinone has some sedative trends and some antidepressant effect.2. The Effect of Nardosinone on primary cultured and neuron oxygen-glucose deprived neural cellsThis part of study was to evaluate the effect of Nardosinone on primary cul ture and oxygen-glucose deprived neuronal proliferation. MTT method was used in this research, the safe dose range was investigated firstly to determine the appropriate dose in vitro, on this basis to determine the effect of Nardosinone on primary culture and oxygen-glucose deprived neuronal proliferation. The results show that, in addition to 48h after administration, the survival rate in the Nardosinone 200μmol. L-1 group was slightly less than 90%, the survival rate in Nardosinone 200μmol. L-1,100μmol.L-1,50μmol.L-1 group at different t i me s were more than 90%. In primary cultured neuronal prol i f era t ion experiments, it showed no statistical differences at different time between the Nardosinone treated group and the control group after treating with Nardosinone,24h after administration Nardosinone 200μmol. L-1,50μmol.L-1 showed some promoting proliferation trend,48 h after administration Nardosinone200μmol.L-1,100μmol.L-1,50μmol.L-1 show some promoting proliferation trend.After oxygen-glucose deprivation for 2h and 4h, the OD value in the damaged group was lower than the control group (P<0.01), indicating oxygen-glucose deprivation damaged the cells. The OD value of 200p mol. L-1 group was significantly higher than that of oxygen-glucose deprivation group 2h after glucose deprivation (p <0.01), the OD value of 100μmol.L-1 was significantly higher than that of oxygen-glucose deprivation group 4h after glucose deprivation (p<0.05).The result indicate that Nardosinone 200μmol.L-1,100μmol. L-1,50μmol.L-'has a trend of promoting proliferation in primary culture neuronal cells, has an anti-damage effect on oxygen-glucose deprivation injury.3. The Mechanisim of Nardosinone on neuronal proliferation and resistance to oxygen-glucose deprived damageThis part of study was to investigate the mechanisms of Nardosinone on neuronal proliferation, to determine wether Nardosinone perform its antidepressive activity in MAPK pathway or cAMP pathway. MTT method was used to observe what H89, the PKA inhibitor,and PD98059, the MEK inhibitor act on the effect of Nardosinone. Western blotting was used to observe the expression of Rap-1 and PKA in cAMP pathway, and the expression of MEK1 and ERK1/2 in MAPK pathway. The MTT results showed that H89 and PD98059 could al leviate the increase of OD value induced by Nardosinone, indicating H89 and PD98059 inhibited the action caused by Nardosinone. Elisa results showed that oxygen-glucose depriving could increase the release of LDH. Western blotting results showed that, Nardosinone could increase PKA and Rap-1 expression in cAMP pathway, and MEK1 and p-ERK1/2 expression in MAPK pathway, H89 and PD98059 could inhibit the effect of Nardosinone, indicating Nardosinone may carry out its action in cAMP and MAPK pathway.In summary, Nardosinone showed sedative tendency and antidepressant effects, could promote the primary cultured neural cells proliferation, and could promote neural cells to resist the oxygen-glucose depriving. Thus Nardosinone might perform its anti-depressant activity in cAMP and MAPK pathway. |
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