| Objective Through the establishment of SD rat models of congenital and noncongenital human cytomegalovirus(HCMV) infections, the experiment studied the effects of congenital and noncongenital human cytomegalovirus infection on the expression of subunits of hippocampal NMDA receptors NR1 and NR2 B and the learning and memory ability of filial rats, so as to explore the timing selection and importance of clinical prevention and treatment of cytomegalovirus infection.Methods(1) Eighteen female SPF SD rats aged 8 weeks were selected and paired according to the female-male proportion of 2:1. The pregnant rats were randomly divided into the control group, congenital HCMV infection group and noncongenital HCMV infection group, with 6 rats in each group. On the 7th or 8th day after pregnancy, 0.8ml HCMV suspension with the 50% tissue culture infective dose(TCID50) of 5 × 107L-1 was intraperitoneally injected into the pregnant rats in the congenital HCMV infection group. Equivalent supernatant of human embryonic lung fibroblasts was intraperitoneally injected into the pregnant rats in the control group.And 15 ul HCMV suspension, with the same concentration of that in the congenital HCMV infection group, was intracranially injected into the offspring rats in the noncongenital HCMV infection group on the 2th day after birth.(2) The behavior changes of pregnant rats and their offspring rats before and after the experiment were observed and compared. Six offspring rats were randomly selected from each group 4weeks after birth and their learning and memory abilities were compared and evaluated with the Morris Water Maze.(3) Eight offspring rats 4 weeks after birth were randomly selected from each group. The hippocampal morphological and pathological changes of the offspring rats were then carefully observed in the brain tissues removed before with the HE staining method. The immunohistochemicalmethod was applied to detect the expression of subunits of hippocampal NMDA receptors NR1 and NR2 B.(4) The SPSS16.0 software was adopted for the statistical data analysis.Results(1) Behavior observation: no abnormal behavior was found in the pregnant rats and their offspring rats in the control group, while obvious abnormal behaviors were found in the experimental groups(congenital and noncongenital infection groups)(2) HE staining pathology: in the control group, the hippocampal structure was normal and no nerve cell loss was found. The cells were uniform in neat rows, with intact nuclei and obvious nucleoli. Compared with these of the control group,phenomenons such as different degrees of neuron loss, edema, the loose tissue structure, decreased number of granular layer cells and disappearance of the nucleus were found in the offspring rats of the experimental group(congenital and noncongenital infection groups).(3) Morris Water Maze experiment on offspring rats:the escape latency of offspring rats in the congenital infection group during the 1st to4 th day were respectively(dl:95.83 ± 18.36; d2:70.36 ± 11.52; d3:52.73 ± 11.39;d4:38.96 ± 5.27), which were longer than(dl:46.98 ± 16.74; d2:29.83 ± 10.64;d3:22.41 ± 12.16; d4:15.69 ± 6.24) in the control group, with significant differences(P<0.01);The escape latency of offspring rats in the noncongenital infection group during the 1st to 4th day were respectively(dl:89.69±16.15;d2:68.27±9.83;d3:49.85±12.21;d4:35.41±5.51),which were also longer than control group,with significant differences(P<0.01). The results of Morris Water Maze used to study the space exploration ability showed that the number of times of rats to pass cross the platform was 3.96 ±1.47 in the congenital infection group, as well as 4.38±1.22 in the noncongenital infection group,which was significantly smaller than 7.95±1.59 in the control group(P<0.01). The swimming time in the target quadrant accounted for0.19±0.16 percentage of the total time in the congenital infection group and it was0.23±0.10 percentage in the noncongenital infection group, which were both smaller than 0.45 ± 0.12 in the control group, with significant differences(P<0.01).(4)Immunohistochemical results of offspring rats showed that in the hippocampal DGarea, the NR1(0.176 土 0.033) and NR2B(0.120 土 0.029) in the congenital infection group, as well as NR1(0.202土0.036) and NR2B(0.141土0.026) in the noncongenital infection group, were both decreased compared with NR1(0.286 土 0.031) and NR2B(0.182 土 0.024) in the control group, with significant differences(P<0.01).Immunohistochemical results of offspring rats showed that in the hippocampal CA1 area, the NR1(0.232 土 0.021) and NR2B(0.189 土 0.027) in the congenital infection group, as well as NR1(0.257土0.028) and NR2B(0.215土0.024) in the noncongenital infection group, were both decreased compared with NR1(0.321 土 0.026) and NR2B(0.283 土 0.023) in the control group, with significant differences(P<0.01).Conclusion(1)The rat model of HCMV congenital infection group and noncongenital HCMV infection group were established successfully.(2) According to Morris Water Maze experiment results, HCMV congenital infection and noncongenital infection can result in offspring rats learning and memory impaired ability.(3) HCMV congenital infection group and noncongenital infection group offspring rats hippocampus HE staining were observed under light hippocampus, all can appear pathological change.(4) The expression of NR1 and NR2 B subunits in hippocampus of offspring rats were less than the normal control group in hippocampus of offspring rats group and group non congenital infection of of congenitalinfection, this may be one of the leading mechanism of learning and memory functioninjury. |
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