Preliminary Study On The Protective Effect And Mechanism Of Extract Of St.John’s Wort Tablets On Post-traumatic Stress Disorder Model Mice

Objective To investigate the protective effect of extract of St.John’s wort tablets(ESJWT)on post-traumatic stress disorder(PTSD)in model mice,and preliminarily discussed the mechanism.Methods Male C57BL/6 mice were used in this study,aged 8-10 weeks,weight: 20-28 g,randomly divided into normal control group(normal saline,100 μl),model group(normal saline,100 μl),sertraline(15mg/kg,100 μl)and ESJWT(25mg/kg,100 μl)treatment groups,with 10-12 mice for each group.The way of administration were intragastric.Except of the normal control group,all the mice were treated with fifteen intermittent inescapable foot-shocks(intensity: 0.8 m A;interval: 10s;duration: 10s)for 2 days.Establishment the PTSD mice model by short foot-shocks.This study was divided into two parts,the first batch of mice were given drugs at the same time as the model was established.Then,contextual freezing and fecal pellet were tested on the 3rd,8th and 15 th days.In addition,open field test,elevated plus maze test and staircase test were performed on the 16 th,17th and18 th days,respectively.Here,the day that mice were subjected to short foot-shocks was defined as the 1st day.The serum contents of noradrenaline(NE)and 5-hydroxyptamine(5-HT)were evaluated using enzyme linked immunosorbent assay(ELISA)after behavior tests.The second batch of mice were given drugs 10 days before the model was established.Then,contextual freezing test and open field test were performed,respectively.Applicating Quantitative Real-time PCR(RT-PCR)to detect the m RNA level of IL-1β,IL-6,TNF-α,i NOS in hippocampus and prefrontal cortex of mice after behavior tests.Result 1.The first batch of mice.Compared with normal control group,the freezing time percentage and the number of fecal pellet of model group were significantly increased(P< 0.01).Meanwhile,the time and number of entry into the central open field and open arm were decreased(P<0.01).The number of rearing was recorded by the staircase test was significantly increased(P<0.01).Compared with model group,both sertraline and ESJWT showed anti-PTSD effect,(P<0.05,P<0.01).ESJWT treatment also reduced the number of fecal pellet(P<0.01).2.However,no significant changes of the contents of NE and 5-HT in each group.3.The second batch of mice.Compared with normal control group,the freezing time percentage of model group was significantly increased(P<0.01).Meanwhile,the time and number of entry into the central open field were decreased(P<0.01).Compared with model group,the freezing time percentage of ESJWT group was significantly decreased(P<0.05),the time and number of entry into the central open field were increased(P<0.05).4.Compared with normal control group,the m RNA level of pro-inflammatory cytokine(IL-1β,IL-6)in hippocampus and prefrontal cortex of model group were significantly increased(P<0.05,P< 0.01).Meanwhile,the m RNA level of i NOS in hippocampus was significantly increased(P<0.05).Compared with model group,the m RNA level of pro-inflammatory cytokine(IL-1β,IL-6)in hippocampus and prefrontal cortex of ESJWT group were significantly decreased(P<0.05),the m RNA level of i NOS in hippocampus was significantly decreased(P<0.05).However,there was no significant difference between the each group in m RNA level of TNF-α in hippocampus and prefrontal cortex.Conclusion 1.Both preventive and treatment,ESJWT showed anti-PTSD effect in model mice.2.ESJWT can inhibit the increase of pro-inflammatory cytokine in hippocampus and prefrontal cortex of PTSD model mice.