ABSTRACT
Objective To investigate the effect of hypothermia on the learning and memory a-bility of neonatal rats during anesthesia and its possible mechanism.Methods Forty SD rats aged 7 d were randomly divided into 4 groups (n=10):control group (group C),anesthesia group (group A),anesthesia and hypothermia group (group AH),hypothermia group (group H).Group C was in-jected intraperitoneally with 0.1 ml of saline and equipped with heating pad to keep the rectal temper-ature at 38-39℃.Group A was injected with propofol 0.1 ml at 25 mg/kg intraperitoneally with 1/2 of the initial dose,and anesthesia was maintained for 2 h.The same method to maintain the rectal temperature at 38-39℃;Group AH of anesthesia and time and Group A of the same,rats in the anes-thesia process is not insulation,control room temperature of 23℃,allowing the body temperature de-creased;Group H rats intraperitoneal injection of 0.1 ml saline,the same control room temperature of 23℃,so that the natural temperature drop.Anesthesia in the process of continuous oxygen,inter-mittent monitoring of body temperature.Immediately after awake,5 rats in each group were randomly selected to detect the content of p-ERK and p-CREB in hippocampus by Western blot.The spatial learning and memory ability and p-ERK and p-CREB contents in hippocampus were measured by water maze test.Results The rectal temperature in group AH and group H decreased to (25.38± 0.22)℃ and (25.54±0.20)℃ in 1 h respectively,and the body temperature decreased significantly compared with group C(38.36±0.24)℃ and group A(37.40±0.29)℃ (P<0.05).Compared with group C and group A,the expression of group AH and group H was decreased (P<0.05).At the end of the water maze test,the expression of protein in the four groups was not statistically signifi-cant.There was no significant difference between the four groups in the escape latency,the number of crossing the platform and the quadrant of the original platform quadrant.Conclusion The expression of p-ERK and p-CREB in neonatal rats hippocampus can be short-term inhibition in the period of hy-pothermia at 25℃,but no significant effect on the long-term learning and memory ability.
ABSTRACT
Objective To investigate the effects of different doses of remifentanil on learning and memory ability,the expression of hippocampal tissue phosphorylation of cAMP response element binding protein (p-CREB)in developing rats.Methods A total of 72 Sprague-Dawley rats (1 9-23 g) were randomly divided into 4 groups (n =18 each):Group C:normal saline control group;R1,R2, R3 group received continuous intraperitoneal remifentanil 1,5,10 μg·kg-1 ·min-1 for 2 hours re-spectively.Both total volume of remifentanil and saline were 2 ml.The SpO 2 and pulse rates were mo-nitored during the experiment.Step-down test was used to evaluate the learning and memory ability, while Western blot analysis was performed to measure the expression of hippocampal p-CREB protein in 4 h,24 h,1 week when the rats were awake.Results Compared with group C,group R1 and R2, pulse rates of group R3 decreased significantly (P <0.05 ),but the changes of SpO 2 in each group were not statistically significant.At 4 h point:compared with group C and group R1,the error times in step-down test were increased in both group R2 and R3,the latencies were shortened (P <0.05);Compared with group R2,the error times were increased in group R3,latency was shortened (P <0.05).At 24 h point,compared with group C and group R1,the error times were increased in group R2,R3,latencies were shortened (P < 0.05 );Compared with group R2,the error times were in-creased in group R3,latency was shortened (P <0.05 ).The error times and latency of each group had not statistical significance in one week.At 4 h point,the expression of p-CREB protein in hippo-campus of group R3 downregulated compared with group C and group R1,R2,respectively (P <0.05).At 24 h point,the expression of p-CREB protein in hippocampus of group R2,R3 decreased compared with group C and group R1 respectively(P <0.05);The expression of p-CREB protein in each group had no statistical significance in one week.Conclusion 5-10 μg · kg-1 · min-1 dose of remifentanil can result in a decline of learning and memory ability in the developing rats in short-term,and the mechanism may relate to the inhibition of p-CREB protein expression in hippocampus.
ABSTRACT
Objective To investigate the effect of different concentrations of dexmedetomidine on the apoptosis of hippocampal neurons in neonatal rat induced by propofol in vitro. Methods Hippocampal neurons of primary cultured neonatal SD rat were divided randomly into three groups. Group C (control group)was normal cultured without any treatment for 12 h; group P (Propofol group)was incubated with 12 μg/mL propofol for 12 h and group DP (Dexmedetomidine + propofol group)was incubated with 0.002 5 ~ 25 μg/mL dexmedetomidine for 30 min, and then further incubated with 12 μg/mL propofol for 12 h. Results Compared with that of group C, the apoptosis rate of hippocampal neurons increased in group P and DP (P < 0.05 or P < 0.01); Compared with that of group P, the apoptosis rate of neurons decreased with the increase of dexmedetomidine concentration in group DP (P<0.05 or P<0.01). The result of transmission electron microscope indicated that compared with group C , group P showed obvious neuronal damage; the nerve cells damage alleviated in group DP, which were negatively associated with the concentration. Conclusions With the concentration ranging from 0.002 5 to 25 μg/mL, dexmedetomidine set pre-incubation and breeding can reduce apoptosis of hippocampus neuron of neonatal rats induced by propofol and the effect is concentration dependent.