The Effect Of Adolescent Cocaine Exposure On Addiction Susceptibility Behavior During Adulthood And The Mechanism Of MPFC DUSP1 In Mice

Background:Cocaine is a local anesthetic with excitatory central effect,and it is also one of the common drugs of abuse.It is reported that Chinese existing drug addicts have obvious characteristics of younger age,and young drug addicts’ account for more than half.Adolescence is a critical period for brain development and nervous system maturation.Previous studies have shown that adolescent exposure to cocaine(ACE)can lead to emotional and cognitive impairment and increase drug susceptibility and risk during adulthood.However,the brain target and molecular mechanism of ACE on adult addictive behavior are not clear.Medial prefrontal cortex(mPFC)is a key cortical region.It integrates information from many cortical and subcortical regions and gathers information into the output structure.It plays a vital role in cognitive process,emotion regulation,motivation and social interaction.It is also a key target of drug toxicity.mPFC dysfunction has been found in various neuropsychiatric diseases such as addiction,among which glutamatergic dysfunction is considered to be one of the potential mechanisms affecting obsessive-compulsive drug seeking behavior.However,the role and related mechanism of mPFC in adult addictive susceptibility behavior of ACE mice are unclear and need to be further studied.Dual specific phosphatase 1(DUSP1),as an important member of mitogen activated protein kinase(MAPK)phosphatase(MKP)family,plays an important role in regulating human cell growth cycle and tumorigenesis and development through MAPK and other signal pathways.Studies have shown that DUSP1(MKP-1)is not only directly expressed in stress response,but also a key negative regulator of ERK signaling pathway,which induce the occurrence of depressive symptoms.However,there is no relevant research report on the role of DUSP1 in the addictive susceptibility behavior of ACE mice during adulthood.Objective:(1)To clarify the effect of ACE on addictive susceptibility behavior and key brain regions of adult mice;(2)Screen the changes of mPFC transcriptome of adult mice induced by ACE;(3)To explore the mechanism of mPFC DUSP1 of addiction susceptibility behavior of adult mice induced by ACE.Methods:(1)The ACE model was constructed and the conditioned place preference(CPP)behavior test was used to evaluate the addictive susceptibility behavior;(2)c-Fos immunofluorescence staining and calcium signal optical fiber recording were used to detect the neuronal activity and neuronal types of mice in vitro and vivo;(3)The differentially expressed genes in mPFC of ACE adult mice were screened by brain transcriptome sequencing;(4)The mRNA and protein expression levels of DUSP1 pathway were detected by polymerase chain reaction(PCR)and Western blot;(5)The activity of DUSP1 was detected by enzyme linked immunosorbent assay(ELISA);(6)The number of dendritic spines in mPFC of adult mice was detected by ultra-high resolution confocal imaging.Results:(1)Adult ACE mice were more sensitive to the subthreshold dose of cocaine addiction,which was manifested by the formation of CPP induced by cocaine,accompanied by the significant activation of glutamatergic neurons in mPFC sub regions-cingulate cortex area 1(Cgl)and anterior marginal cortex(PrL)and the density of dendritic spines increased;(2)The transcriptome expression profiles of mPFC in ACE adult mice were significantly different,in which DUSP1 was significantly up-regulated,and the pathway of up-regulated differential genes was mitogen activated protein kinase(MAPK)signal pathway;(3)The level of mPFC DUSP1 gene of adult mice with ACE was verified to be increased,but its protein level and enzyme activity decreased significantly,accompanied by the significant increase of ERK1/2、CREB、c-fos and BDNF protein activities;(4)Selective knockdown of DUSP1 in mPFC brain area significantly enhanced the addictive susceptibility behavior of ACE adult mice,accompanied by a significant increase in the expression level of ERK1/2 protein activity in mPFC and an increase in the number of dendritic spines.Conclusion:(1)ACE enhanced the addictive susceptibility behavior of adult mice,accompanied by the increased activity of mPFC glutamatergic neurons;(2)Specifically knocking down DUSP1 of mPFC glutamatergic neurons enhances the addictive susceptibility behavior of ACE mice during adulthood;(3)DUSP1 negatively regulates ERK pathway,and then regulates the addictive susceptibility behavior of ACE mice during adulthood.