Effects Of Ketamine Plus Fluoxetine On NNOS-dexrasl Pathway In Prefrontal Lobe Of Depressed Rats

Objective To investigate the effect of ketamine plus fluoxetine on depressed behavior and the expression of neuronal nitric oxide synthase (nNOS)-Dexrasl pathway in prefrontal lobe of mentally depressed rats in different time. So as to study the possible mechanism of ketamine plus fluoxetine induces antidepressant behavior.Methods One hundred and five healthy adult male SD rats aged2.5-3months weighing220-270g were induced as the rodent model of depression by chronic unpredictable mild stress (CUMS). After the models of depression were established, selected96of CUMS modeling successfully depressed rats. Then they were randomly divided into four groups (n=24each):the depressed group (group D, untreated group), ketamine group (group K, treated with intraperitoneal injection of ketamine10mg/kg for3days or7days), fluoxetine group (group F, treated with gavage of fluoxetine1.8mg/kg for3days or7days), or ketamine plus fluoxetine group (group KF, treated with intraperitoneal injection of ketamine10mg/kg plus gavage of fluoxetine1.8mg/kg for3days or7days). Open field test and sucrose preference test were performed at1d before and after depression model was established and1d after treatment. Morris water maze test was used to assess learning memory. The rats were sacrificed on one day after the last test. Immunohistochemisity and western-blot were carried out to measure the expression of nNOS and CAPON in prefrontal lobe. Immunofluorescence was carried out to measure the expression of Dexrasl in prefrontal lobe of rats. The expression of nNOS mRNA, CAPON mRNA and Dexrasl mRNA were detected by using reverse transcription polymerase chain reaction.Results (1) Open-field Test:After the models of depression were established, the total distance traveled and incidence of rearing were decreased significantly from those before (P<0.05).There was no significant difference among all groups in the total distance traveled and incidence of rearing before treatment (P>0.05). After rats underwent3days treatment, the total distance traveled and incidence of rearing in groups K3and KF3increased significantly greater than those of either group D3or group F3(P<0.05). After rats underwent7days treatment, the total distance traveled and incidence of rearing in groups K7, F7and KF7increased significantly greater than those of group D7(P<0.05); the total distance traveled and incidence of rearing in group KF7increased significantly greater than those of group F7(P<0.05).(2) Sucrose Preference Test:After the models of depression were established, the SPP were decreased significantly (P<0.05). There was no significant difference among all groups in their sucrose preference percentage (SPP) before treatment (P>0.05). After rats underwent3days treatment, the SPP in groups K3and KF3increased significantly greater than those of either group D3or group F3(P<0.05). After rats underwent7days treatment, the SPP in groups K7, F7and KF7increased significantly greater than those of group D7(P<0.05); the SPP in group KF7increased significantly greater than those of group F7(P<0.05).(3) Morris Water Maze Test:There was no significant difference among each group before treatment (P>0.05). After rats underwent7days treatment, compared with group D7, group K7and KF7exhibited the escape latency (EL) shortened (P<0.05) and space exploration time (SET) prolonged (P<0.05). However, there was no significant difference on EL and SET between the other groups (P>0.05).(4) The expression of nNOS, CAPON and Dexrasl in prefrontal lobe:Compared with group D3, a significant increase in the expression of either CAPON protein and mRNA or Dexrasl protein and mRNA in prefrontal lobe were determined in groups K3and KF3(P<0.05), while nNOS protein and mRNA expression significantly decreased in groups K3and KF3(P<0.05). Compared with group D7, a significant increase in the expression of either CAPON protein and mRNA or Dexrasl protein and mRNA in prefrontal lobe were determined in groups K7, F7and KF7(P<0.05), while nNOS protein and mRNA expression significantly decreased in groups K7, F7and KF7(P<0.05). Compared with group F7, group KF7exhibited lower expression of nNOS protein and mRNA in prefrontal lobe (P<0.05), whereas group KF7showed added expression of either CAPON protein and mRNA or Dexrasl protein and mRNA in prefrontal lobe (P<0.05).Conclusions (1) Ketamine can improve depressive behavior of rats and alleviate learning/memory impairment in depressed rats.(2) The results indicate that co-administration of antidepressant fluoxetine with ketamine may induce a more pronounced antidepressant activity than treatment with each antidepressant alone. It could shorten the time to improve depressive behavior.(3) The effects of ketamine plus fluoxetine on depressed rats may due to the balance of the nNOS and CAPON protein in prefrontal lobe of depressed rats.