The Role Of TS^Glu—vMHb^ChATPathway And The Therapeutic Effects Of Siegesbeckiae Herba On METH-Primed Reinstatement In Mice

BACKGROUND:Methamphetamine（METH）is the main ingredient of "crystal METH".The abuse of METH is increasing rapidly year by year,and METH has become one of the main drugs of abuse in China,Relapse:drug dependent individuals resume drug psycho-effect desire,seek and use drugs again after a period of drug withdrawal,due to the irritation of some factors.At present,the neural pathway of METH relapse and its mechanism are still not clear,which leads to the lack of effective drugs and intervention methods for the treatment of addiction and psychiatric comorbidities.Triangular septum（TS）,a part of septum nuclei in the limbic system,is a triangular nucleus located below the corpus callosum,dominated by Glutamate（Glu）neurons(TS^Glu).TS emits projections to the medial habenula（MHb）.The MHb is thought to be a key brain region in the control of mood and biorhythms,and is involved in the formation of addictive behaviors for drugs such as cocaine,nicotine and morphine.Ventromedial habenula（vMHb）is one of the most abundant brain regions of cholinergic neurons in the whole brain（vMHbChAW）,which mainly receives the projection of TS and forms the TS—vMHb pathway.Whether there is direct projection between TS^Glu" and vMHb^ChAT and its specific function are still unclear.Specific inhibition of TS—vMHb projection can reduce spontaneous motor activity and anxiety-like behavior in mice.Studies have found that vMHb^ChAT is highly excited during the cocaine reinstatement,and a single injection of METH can also activate vMHb^ChAT,suggesting that vMHbChAr may be a key brain target for METH relapse.Is the high activity of vMHb^ChAT related to regulation of TS^Glu?Does the TS^Glu—vMHb^ChAT pathway participate in METH relapse?Siegesbeckiae Herba is cold and tastes bitter,and belongs to the liver and kidney meridians.It has the effect of clearing away heat and detoxifying and anti-inflammation.In modern Chinese medicine,Siegesbeckiae Herba is commonly used to treat chronic inflammation and other "heat toxic"diseases.According to the theory of traditional Chinese medicine,addiction is a complex syndrome of toxicity,cold and heat.METH patients often show " sthenic fever " symptoms such as excitement,insomnia,anxiety,mania,and even seizures.So,can Siegesbeckiae Herba interfere with METH relapse behavior?AIMS:In this paper,the mice METH-primed reinstatement model was used to explore（1）the physiological structure and function of the TS—vMHb pathway;（2）The mechanism of the TS^Glu—vMHb^ChAT pathway of mice METH-primed reinstatement behavior;（3）Interventional effect of Siegesbeckiae Herba on METH-primed reinstatement behavior in mice.METHODS:By establishing mice METH conditioned place preference（CPP）model,we detected METH-primed reinstatement behavior in mice and the intervention effect of Siegesbeckiae Herba;The activity of TS^Glu and vMHb^ChAT neurons were detected by immunofluorescence staining,in vivo optical fiber recording and in vitro patch clamp technique.The regulation effect of TS^Glu—vMHb^ChAT pathway on METH-primed reinstatement behavior was observed by using chemical genetic method.The regulation of Siegesbeckiae Herba on TS^Glu—vMHb^ChAT pathway in mice with METH-primed reinstatement was detected.RESULTS:（1）There is a direct projection between TS^Glu and vMHb^ChAT,and the inhibition of TS^Glu reduced the excitability of vMHb^ChAT;（2）The expression of c-fos and action potential in TS and vMHb brain regions in METH-primed mice increased,conditioned inhibition of TS^Glu or vMHb^ChAT decreased METH-primed reinstatement behavior of mice,conditioned activation of vMHb^ChAT enhanced METH-primed reinstatement behavior of mice;（3）In vivo conditional inhibition of the TS^Glu—vMHb^ChAT pathway decreased METH reignition behavior in mice;（4）Siegesbeckiae Herba decreased METH-primed reinstatement behavior and c-fos expression in TS and vMHb in mice.CONCLUSION:（1）TS^Glu emits glutamatergic projections to vMHb^ChAT;（2）Inhibition of TS^Glu can reduce the excitability of vMHb^ChAT;（3）The TS^Glu—vMHb^ChAT pathway is involved in the regulation of mice METH-primed reinstatement;（4）Siegesbeckiae Herba can alleviate METH-primed reinstatement in mice,and TS^Glu—vMHb^ChAT pathway may be an important target.