Mechanisms of serotonin transporter and serotonin 1A receptor in the different susceptibility of chronic unpredictable stress / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the expression of serotonin transporter (5-HTT) and serotonin 1A treceptor (5-HT1 A R) located in the chronic unpredictable stress (CUS)-relative brain areas (mPFC,VTA,NAc) in high and low CUS susceptibility rats,thus to unveil the possible mechanism lead to the different CUS susceptibility.Methods One hundred and fifty male Sprague-Dawley rats were randomly assigned into experiment group (n =120) and control group (n =30).Rats in experiment group were trained according to established CUS procedure.OFT and FST were used to assess the different susceptibility to CUShigh susceptibility group (H group)and low susceptibility group (L group).After the model was established,rats were scarified and cardio-perfused,and the brains were removed and sliced up coronarily.The sections including ventral tegmental area (VTA),nucleus accumben (NAc),medial prefrontal cortex (mPFC) were selected.The mRNA levels of 5-HTT and 5-HT1AR in the regions were estimated with in situ hybridization.Results The expression of 5-HTT in H group were significantly lower than that of in the control and L group in all regions (mPFC169.20 ± 8.23 vs 143.53 ±5.31 ; Nac177.41 ± 5.68 vs 158.65 ± 5.24 ; VTA174.16 ± 5.61 vs 158.65 ± 4.85),and the difference between the H and L group was significant(P＜0.01) ;however,the expression of 5-HT1AR in H group were significantly higher than that of in the control and L group in all regions (mPFC113.98 ± 7.46 vs 125.90 ± 3.30 ; Nac112.11± 5.50 vs 125.06 ± 3.97 ;VTA103.11 ± 6.05 vs 115.57 ± 3.19),and the difference between the H and L group was significant (P＜ 0.01).Conclusion The overexpression of 5-HT1AR and down regulation of 5-HTT in the circuit of VTA-NAc-mPFC may be the basis of the high susceptibility to CUS.