Changes In Sexual Performance And Biochemical Characterization Of Functional Neural Regions: A Study In Serotonin Transporter(SERT)Knockout Male Rats

Introduction:premature ejaculation,as the most common ejaculation disorders,brings huge troubles to both sexologists and patients.The etiology and pathogenesis of ejaculation regulation are still unclear by now.Disturbed 5-HT homeostasis has been considered to be closely related to ejaculation status,which is affected by the SERT expression in the presynaptic nerve terminals.Hence,the SERT has been highlighted for ejaculation regulation.However,the role that SERT expression involving in sexual activities is indefinite.Aim:This study aimed to explore the correlation between SERT expression and sexual activities and seek the possible mechanism SERT involving in regulating ejaculations.Materials and Methods:By target-selected mutagenesis,we generated the SERT^+/-,SERT^-/-and SERT^+/+male rats.After obtaining steady sexual behaviours with the induced female rats,the parameters of sexual behaviours in SERT^+/-?n=6?,SERT^-/-?n=6?and SERT^+/+?n=6?male rats were recorded,respectively.Subsequently,the three genotypes male rats were killed immediately and several relevant brain tissues and spinal cord were dissected and used for SERT mRNA,SERT protein and 5-HT examinations by QRT-PCR,Western blots and Elisa,respectively.Results:The SERT^-/-group had lower sexual performances,showing fewer ejaculations and a longer ejaculation latency than the SERT^+/+group,while the SERT^+/-group didn't differ significantly from the SERT^+/+group in sexual performance.The SERT^-/-group showed an almost complete absence of SERT mRNA and protein expression in all measured regions.In the SERT^+/-group,the SERT mRNA and SERT protein expressions were downregulated by approximately 50%and 35%,respectively,compared to the SERT^+/+group.The SERT^-/-group had the highest 5-HT level than that of the SERT^+/+group and SERT^+/-group.In addition,there are differential expression of SERT protein in five regions of all three groups.Conclusions:Present study confirmed differential SERT expression played a key role in sexual performances.A certain amount of SERT protein may be critical to sexual performance.Therefore,Polymorphisms of the SERT gene should still be highlighted for ejaculation regulation research.