| Objectives: To investigate the effects of low-dose ketamine combinedwith propofol on the anti-depression efficacy in stressed rats undergoingElectroconvulsive shock (ECS) and its impact on expression andphosphorylation of AMPAR subunit glutamate receptor1(GluR1) andGABAAR.Methods: Sprague-Dawley rats were stressed by chronic unpredictablemild stress (CUMS). Fifty mentally stressed rats were allocated into5groups(n=10per group): the stressed group (with no application, group D), ECSgroup (applied with ECS after intraperitoneal injection of normal saline8ml/kg, group E), ketamine+ECS group (applied with ECS afterintraperitoneal injection of ketamine10mg/kg, group KE), propofol+ECSgroup (applied with ECS after intraperitoneal injection of propofol80mg/kg,group PE) and ketamine+propofol+ECS group (applied with ECS after intraperitoneal injection of ketamine10mg/kg and propofol80mg/kg, groupKPE). All groups except group D underwent ECS once a day for7consecutivedays. Sucrose preference test, open-field test and Morris water maze wereperformed to assess the depressive behavior. Immunohistochemistry was usedto assay the GluR1and GABAAR expression in hippocampal CA1, and CA3areas. Phosphorylation of GluR1and GABAAR were respectively evaluated byWestern blot.Results:(1) Sucrose Preference Test: Among all groups, there were nosignificant differences in their SPPs before CUMS procedure (P=0.59). AfterCUMS, their SPPs were significantly lower than those of pre-CUMS in eachgroup (P<0.05). After application of anesthesia and ECS, the SPPs of rats ingroups E, KE and PE were higher than those of rats in group D (P<0.05).Butthere were no significant differences of SPPs among groups E, KE and PE(P>0.05). Moreover, the SPPs of rats in group KPE were significantly higherthan those of rats in other4groups (P<0.05).(2) Open field Test: No significant difference of OFT scores was foundin all groups before CUMS and ECS application (total distance traveled,P=0.737and0.317respectively; number of rearing, P=0.116and0.998respectively). After application, the total distance traveled and incidence ofrearing of rats in groups E, KE and PE were observed higher than those of ratsin group D(total distance traveled, P<0.05; number of rearing, P<0.05).However, there were no significant difference among groups E, KE and PE (total distance traveled, P>0.05; number of rearing, P>0.05). Meanwhile,these values in group KPE were greater than those of rats in other4groups(total distance traveled, P<0.05; number of rearing, P<0.05).(3) Morris Water Maze: Before application of ECS, there was nosignificant difference of EL and SET in all groups (EL, P=0.710; SET,P=0.080). Compared with group D, group E showed higher EL and lowerSET (P<0.05) after application, whereas group KPE showed lower EL andlonger SET (P<0.05). However, no significant differences of EL and SET(P>0.05) were observed between group D and group KE, also between groupD and group PE. Compared with group E, groups KE, PE and KPE revealedlower EL (P<0.05), whereas SET was increased in the above-mentioned threegroups (P<0.05). Compared with group KE and group PE, lower EL andhigher SET (P<0.05) were existed in group KPE.(4) The expression of AMPA GluR1and GABAAR in hippocampus:Compared with group D, the expression of GluR1were increased in other fourgroups, the expression of GABAAR were decreased in groups E, PE and KPE(P<0.05), while there was no significant difference of GABAAR expression ingroup KE (P>0.05);Compared with group E, groups KE and KPE showedhigher expression of GluR1and GABAAR, while group PE showed lowerexpression of GABAAR; Compared with group PE, an increased expression ofGluR1and GABAAR was found in group KPE (P<0.05).(5) The ratio of AMPA GluR1/GABAAR: Compared with group D, the ratio of GluR1/GABAAR were up-regulated in other four groups (P<0.05);Compared with groups E, KE and PE, the ratio of GluR1/GABAAR wasup-regulated in group KPE (P<0.05), but there were no significant differenceof GluR1/GABAAR ratio among groups E, KE and PE (P>0.05).(6) Phosphorylation of GluR1Ser845and GABAARγ2Ser327inhippocampus: Compared with group D, the expression of p-GluR1,p-GABAAR were increased in groups E, PE and KPE (P<0.05), while groupKE showed higher level of p-GluR1and lowered expression of p-GABAAR(P<0.05). Compared with group E, group KE exhibited higher level ofp-GluR1and lowered expression of p-GABAAR (P<0.05), group PE showedincreased level of p-GluR1, p-GABAAR (P<0.05).Compared with Group E,group KPE exhibited greater expression of p-GluR1and p-GABAAR(P<0.05).Compared with group KE, group PE revealed decreased level ofp-GluR1and increased expression of p-GABAAR (P<0.05), group KPEshowed higher expression of p-GluR1and p-GABAAR (P<0.05). Comparedwith group PE, an increased expression of p-GluR1and reduced level ofp-GABAAR were found in group KPE (P<0.05).(7) The ratio of phosphorylation of AMPA GluR1/GABAAR: Comparedwith group D, the ratio of p-GluR1/p-GABAAR were increased in groups E,KE, PE and KPE (P<0.05). Compared with group E, group KE exhibitedhigher ratio of p-GluR1/p-GABAAR (P<0.05), group PE showed no changesin p-GluR1/p-GABAAR ratio (P>0.05).Compared with Group E, group KPE exhibited greater ratio of p-GluR1/p-GABAAR (P<0.05).Compared withgroup KE, group PE and KPE revealed lowered ratio of p-GluR1/p-GABAAR(P<0.05). Compared with group PE, an increased ratio of p-GluR1/p-GABAAR were found in group KPE (P<0.05).(8) Correlation analysis of the index between expreesion of protein andethology test of rats: The expression of AMPA GluR1and GluR1/GABAARratio in CA1ans CA3hippocampal have correlations with SPP, total distancetraveled and incidences of rearing; GluR1has correlation with learning scoresand GABAAR expression has correlation with memory scores.(9) Correlation analysis of the index between phosphorylation of proteinand ethology test of rats: p-GluR1and p-GluR1/p-GABAAR ratio inhippocampal have correlations with SPP, total distance traveled andincidences of rearing; while p-GluR1, p-GABAAR and p-GluR1/p-GABAARratio were only highly negative correlation with EL.Conclusions: Low-dose ketamine combined with propofol may play arole in enhancing the anti-depression efficacy of ECS in stressed rats,ameliorating the cognitive impairment associated with ECS, possibly byup-regulating the ratio of GluR1/GABAAR and balancing the ratio of p-GluR1and p-GABAAR in hippocampus of stressed rats. |
