The Expression Of Drd1/Drd2/Mir-9/Mir-504in The Nucleus Accumbens And Striatum Of Depressive Rats Induced By Chronic Psychological Stress

Objective To study the effect of maternal deprivation and chronic unpredictable stress on the depressive behavior and the expression of dopamine D1receptor gene (DRD1), dopamine D2receptor gene (DRD2), miR-504and miR-9in the nucleus accumbens and striatum of rats; To explore whether there was the interaction between the two stress and whether the region specific alteration in miR-504and miR-9was involved in the regulation mechanism of DRD1and DRD2expression.Methods Newborn rats were randomly divided into four groups, control (C) group (n=20), maternal deprivation (MD) group (n=19), chronic unpredictable stress (CUS) group (n=18), and dual stress (DS) group (n=17). MD rats received maternal deprivation from postnatal day1through14. CUS rats received chronic unpredictable stress for21days when they are10weeks old. DS rats received both maternal deprivation from postnatal day1through14and chronic unpredictable stress for21days when they are10weeks old. Control rats received no experimental handle. Behavior tests include sucrose preference test, open field test, forced swimming test in order to evaluate rats’depressive behavior in the thirteen weeks. Sucrose preference test was carried out to evaluate the percentage of sucrose intake from the total intake. Forced swimming test was carried out to evaluate duration time of floating. Open field tests were carried out to evaluate craw distance, the rate of central area, vertical movement, number of stool. All the rats were rapidly decapitated after behavioral tests, and the nucleus accumbens and striatum were rapidly dissected. miR-9/miR-504and DRD1/DRD2mRNA expression in the nucleus accumbens and striatum were detected by Real-Time PCR. DRD1/DRD2protein expression in the nucleus accumbens and striatum was detected by Western Blot.Results1. the result of behavior tests:(1) the result of sucrose preference test:the effect of MD and CUS on the sucrose preference was not significant (P>0.05). But their interaction on the sucrose preference was significant (P<0.05).(2) the result of forced swimming test:the effect of MD and interaction of MD and CUS on the duration time of floating had not significant effect (P>0.05), while the effect of CUS was significant (P<0.05).(3) the result of open field tests:1) craw distance: the effect of MD and interaction of MD and CUS on the craw distance had not significant effect (P>0.05), while the effect of CUS was significant (P<0.05).2) The rate of central distance:MD on the rate of central distance had significant effect (P<0.05). But the effect of CUS and interaction of MD and CUS was not significant (P>0.05).3) vertical movement:the effect of MD and interaction of MD and CUS on the vertical movement had not significant effect (P>0.05), while the effect of CUS was significant (P<0.05).4) the number of stool:MD on the number of stool had significant effect (P<0.05). But the effect of CUS and interaction of MD and CUS was not significant (P>0.05).2. The expression of miR-9and miR-504:(1) In the nucleus accumbens:MD on the expression of miR-9and miR-504both had not significant effect (P>0.05). CUS on the expression of miR-9had significant effect (P<0.05), but had not significant effect on the expression of miR-504(P>0.05). Their interaction on the expression of miR-9was not significant (P>0.05), and was significant on the expression of miR-504(P<0.05).(2) In striatum:the effect of MD and interaction of MD and CUS on the expression of miR-9and miR-504were significant (P<0.05), while the effect of CUS was not significant (P>0.05).3. The expression of DRD1and DRD2mRNA:(1) In the nucleus accumbens:MD on the expression of DRD1and DRD2mRNA both had significant effect (P<0.05). The effect of CUS and interaction of MD and CUS on the expression of DRD1and DRD2mRNA were not significant (P>0.05)(2) In striatum:the effect of MD and CUS on the expression of DRD1and DRD2mRNA were not significant (P>0.05), while their interaction was significant (P<0.05).4. The relationship between miRNA and mRNA:There was a significant relationship between miR-504and DRD1mRNA level in the nucleus accumbens(P<0.05), miR-9and DRD2mRNA level in striatum (P<0.05). but There was no significant relationship between miR-504and DRD1mRNA level in striatum (P>0.05), miR-9and DRD2mRNA level in the nucleus accumbens (P>0.05).5. The expression of DRD1and DRD2probein:(1) In the nucleus accumbens:MD on the expression of DRD1and DRD2probein had both significant effect (P<0.05). However, CUS had neither significant effect on the expression of DRD1probein nor DRD2(P>0.05). Their interaction on the expression of DRD1probein was not significant (P>0.05),but was significant on the expression of DRD2probein (P<0.05).Conclusion1. CUS would derectly induce depressive-like behavior in rats. MD enhances depressive behavioral vulnerability to stress. In other words, DS group rats appeared to more obvious depressive-like behavior than CUS group rats. 2. MD would induce region specific alterations in miR-9/DRD2and miR-504/DRD1. In other words, the effect of MD was significant on the expression of DRD1/DRD2mRNA and protein in the nucleus accumbens. However, in striatum, MD would influence the expression of miR-9and miR-504, as well as DRD2protein. And miR-9woule be involved in the regulation mechanism of DRD2expression in striatum.3. The effect of CUS on the expression of miR-9/DRD2and miR-504/DRD1was limited, because CUS only affected the alteration in miR-9in the nucleus accumbens.5. MD is a vulnerability factor for the expression of miR-504/DRDl protein in the nucleus accumbens and miR-9/DRD2mRNA in striatum. In other words, miR-504/DRD1protein expression in the nucleus accumbens and miR-9/DRD2mRNA expression in striatum in DS group rats appeared to more obvious alteration than CUS group rats. And miR-504woule be involved in regulation mechanism of DRD1expression in the nucleus accumbens.