Low-Dose Ketamine Combined With Propofol Regulates The Croos-talk Between Inflammation And Glutamate To Alleviate Learning/Memory Impairments In Depressive Rats Receiving Electroconvulsive Shock

Object To investigate the effects of low-dose ketamine combined with propofol on depressive-like behavior and learning/memory function in depressive rats undergoing electroconvulsive shock (ECS, the analog of ECT in animals), and further study the moderating effects of low-dose ketamine combined with propofol on neuroinflammation and glutamate uptake function in the context of ECS treatment, so as to elucidate the underlying molecular mechanisms of low-dose ketamine combined with propofol alleviate ECS-induced learning/memory impairment from the perspective of regulates the cross-talk between inflammation and glutamate.MethodsPart ⅠSixty healthy adult male Sprague-Dawley rats (200-250 g; 2-3 months old) were randomly assigned to 5 groups (n=12 in each group):control group (group C), depression model group (group D), ECS group (group DE), propofol+ECS group (group DPE), and propofol group (group DP). Group C was the control group of healthy rats without treatment; the rats in other groups were treated with the chronic unpredictable mild stress (CUMS) procedure to establish a model of depression. After the CUMS procedure to be completed, rats in group D were given Normal saline (8mL/kg, i.p.) and then subjected to sham ECS treatment; rats in group DE were given Normal saline (8mL/kg, i.p.) and then subjected to ECS treatment; rats in group DPE were given propofol (80 mg/kg, i.p.) and then subjected to ECS treatment; rats in group DP were given propofol (80 mg/kg, i.p.) and then subjected to sham ECS treatment. The sham ECS was handled identically as ECS without current. The aforementioned treatments were given once a day for 7 days. Sucrose preference test, open-field test and Morris water maze were used to assess behavioral changes. The expression levels of Iba-1, GFAP, IL-1β mRNA, TNF-α mRNA, EAAT1 and EAAT2 were measured by immunohistochemistry, real-time PCR and western blot. High performance liquid chromatography was used to detect hippocampal glutamate concentrations.Part ⅡExperiment 1:Sixty healthy adult male Sprague-Dawley rats (200-250 g; 2-3 months old) were randomly assigned to 5 groups (n=12 in each group):control group (group C), depression model group (group D), ECS group (group DE), ketamine+ECS group (group DKE), and ketamine group (group DK). Group C was the control group of healthy rats without treatment; the rats in other groups were treated with the chronic unpredictable mild stress (CUMS) procedure to establish a model of depression. After the CUMS procedure to be completed, rats in group D were given Normal saline (8mL/kg, i.p.) and then subjected to sham ECS treatment; rats in group DE were given Normal saline (8mL/kg, i.p.) and then subjected to ECS treatment; rats in group DKE were given ketamine (10 mg/kg, i.p.) and then subjected to ECS treatment; rats in group DK were given ktamine (10 mg/kg, i.p.) and then subjected to sham ECS treatment. The sham ECS was handled identically as ECS without current. The aforementioned treatments were given once a day for 7 days. The behavioral testing and biochemical assays identical to the first part of the experiment.Experiment 2:Thirty-Six healthy adult male Sprague-Dawley rats (200-250 g; 2-3 months old) were included and chronic unpredictable mild stress (CUMS) procedure to establish a model of depression. After the CUMS procedure to be completed, rats were randomly assigned to 3 groups (n=12 in each group):propofol+ECS group (group DPE), propofol +ketamine+ECS group (group DPKE) and propofol+MK801+ECS group (group DPME). Rats in group DPE were given propofol (80 mg/kg, i.p.) and then subjected to ECS treatment; rats in group DPKE were given propofol (80 mg/kg, i.p.) plus ketamine (10 mg/kg, i.p.), and then subjected to ECS treatment; rats in group DPME were given propofol (80 mg/kg, i.p.) plus MK801 (1mg/kg, i.p.), and then subjected to ECS treatment. The sham ECS was handled identically as ECS without current. The aforementioned treatments were given once a day for 7 days. The behavioral testing and biochemical assays identical to the first part of the experiment.ResultPart Ⅰ(1) Before ECS treatment, rats in the four CUMS-treated groups (groups D, DE, DPE, DP) exhibited significantly decreased in sucrose preference percentage (SPP), horizontal ambulation(i.e. Number of crossed squares) and number of rearing compared with rats in group C (P<0.05), while those values among the four CUMS-treated groups were not significantly different (P>0.05). After ECS treatment, the SPP, horizontal ambulation and number of rearing of the group DE and group DPE exhibited significantly increased in comparison with group D (P<0.05). However, those values of group DPE were still less than those of the rats in group DE (P<0.05).(2)The swimming speeds of rats were similar between groups during all procedures (P>0.05). Before ECS treatment, rats in the four CUMS-treated groups (groups D, DE, DPE, DP) exhibited increased escape latencies and decreased space exploration time compared with those of rats in group C (P<0.05), while there were no difference in either escape latencies or space exploration time between the four CUMS-treated groups (P>0.05). After ECS treatment, compared with group D, the group DE and group DPE showed significantly prolonged escape latencies and shortened space exploration time (P<0.05). Compared with group DE, the group DPE demonstrated shorter escape latencies and longer space exploration time (P<0.05).(3) ECS induced the neuroinflammation and glutamate uptake dysfunction. Compared with group D, the group DE displayed markedly increased expression of Iba-1 and GFAP (P<0.05), higher mRNA levels of IL-1β and TNF-α (P<0.05), decreased expression of EAAT2 and increased concentrations of glutamate in the hippocampus (P<0.05). Propofol partially reversed the ECS-induced neuroinflammation and glutamate uptake dysfunction. Compared with group DE, the group DPE demonstrated decreased expression of Iba-1 and GFAP (P<0.05), lower mRNA levels of IL-1β and TNF-α (P<0.05), increased expression of EAAT2 and decreased concentrations of glutamate in the hippocampus (P<0.05). There was no significant difference in the expression levels of EAAT1 between groups.Part ⅡExperiment 1:(1) Before ECS treatment, rats in the four CUMS-treated groups (groups D, DE, DKE, DK) exhibited significantly decreased in sucrose preference percentage (SPP), horizontal ambulation and number of rearing compared with rats in group C (P<0.05), while those values among the four CUMS-treated groups were not significantly different (P>0.05). After ECS treatment, the SPP, horizontal ambulation and number of rearing of the group DE, group DKE and group DK exhibited significantly increased in comparison with group D (P<0.05). However, there was no significant difference in the SPP, horizontal ambulation and number of rearing between group DE and group DKE.(2)The swimming speeds of rats were similar between groups during all procedures (P>0.05). Before ECS treatment, rats in the four CUMS-treated groups (groups D, DE, DKE, DK) exhibited increased escape latencies and decreased space exploration time compared with those of rats in group C (P<0.05), while there were no difference in either escape latencies or space exploration time between the four CUMS-treated groups (P>0.05). After ECS treatment, compared with group D, the group DE and group DKE showed significantly prolonged escape latencies and shortened space exploration time (P<0.05). Compared with group DE, the group DKE demonstrated shorter escape latencies and longer space exploration time (P<0.05).(3) ECS induced the neuroinflammation and glutamate uptake dysfunction. Compared with group D, the group DE displayed markedly increased expression of Iba-1 and GFAP (P<0.05), higher mRNA levels of IL-1β and TNF-α (P<0.05), decreased expression of EAAT2 and increased concentrations of glutamate in the hippocampus (P<0.05). ketamine partially reversed the ECS-induced neuroinflammation and glutamate uptake dysfunction. Compared with group DE, the group DKE demonstrated decreased expression of Iba-1 and GFAP (.P<0.05), lower mRNA levels of IL-1β and TNF-α (P<0.05), increased expression of EAAT2 and decreased concentrations of glutamate in the hippocampus (P<0.05). There was no significant difference in the expression levels of EAAT1 between groups.Experiment 2:(1) Before ECS treatment, there was no significant difference in the SPP, horizontal ambulation and number of rearing between groups(P>0.05). After ECS treatment, compared with group DPE, the group DPKE and group DPME showed significantly increased SPP, horizontal ambulation and number of rearing(P<0.05). However, those values were not significantly different between group DPKE and group DPME (P>0.05).(2)The swimming speeds of rats were similar between groups during all procedures (P>0.05). Before ECS treatment, there was no significant difference in either escape latencies or space exploration time between groups (P>0.05). After ECS treatment, compared with group DPE, the group DPKE and group DPME showed significantly shortened escape latencies and prolonged space exploration time (P<0.05). However, there was no significant difference in either escape latencies or space exploration time between group DPKE and group DPME (P>0.05).(3) Propofol combined with low-dose ketamine or NMDA receptor antagonist MK801 can further alleviate the ECS-induced neuroinflammation and glutamate uptake dysfunction. Compared with group DPE, the group DPKE and group DPME showed significantly decreased expression of Iba-1 and GFAP (P<0.05), lower mRNA levels of IL-1β and TNF-α (P<0.05), increased expression of EAAT2 and decreased concentrations of glutamate in the hippocampus (P<0.05). However, there was no significant difference for these biochemical indicators between group DPKE and group DPME (P>0.05).Conclusions(1) ECS has a good antidepressant effect, but can result in learning and memory impairment. The underlying molecular mechanisms of learning and memory impairment induced by ECS were associated with neuroinflammation and glutamate uptake dysfunction in depressive rats.(2) Propofol moderately weakened the antidepressant effect of ECS, but can effectively alleviate the learning memory impairment induced by ECS. This protective effect of cognitive was mainly attributed to propofol reduced the ECS-induced neuroinflammation and glutamate uptake dysfunction in depressive rats.(3) Low-dose ketamine (10mg/kg, I.P.) has antidepressant effects, but not further augment the antidepressant effect of ECS in the absence other anesthetics. However, low-dose ketamine can enhance the antidepressant effect of ECS with propofol anesthesia.(4) Low-dose ketamine alone can alleviate the ECS-induced learning and memory impairment. Furthermore, low-dose ketamine can further improve the learning and memory capacities of depressive rats which received ECS under propofol anesthesia. This protective effect of cognitive was mainly attributed to ketamine inhibited NMDA receptor excessive activation, thus effectively reduced the ECS-induced neuroinflammation and glutamate uptake dysfunction.