Mechanisms Of Learning And Memory Impairments In Hippocampus Of Rat Offspring Caused By HCMV Infection During Early Pregnancy

PART ONE Experimental Study of Neonatal Rat Hippocampus Nerve Cells Infected with Human Cytomegalovirus in vitroAbstract Objective To prove human cytomegalovirus (HCMV) infecting neonatal murine hippocampus nerve cells in vitro, providing a cellular model and experimental evidence for congenital nervous infection induced by HCMV and hippocampal learning-memory damage mechanism Methods Proliferatived with HEFL cells, cytopathic effect was +++～++++ within 24～48 hours, 5×10~4/ml cell suspension of HCMV AD169 strain was inoculated to monolayer nerve cell media of SD neonatal rat hippocampal nerve cells. Cytopathic effect (CPE) was observed every day with microscope. HCMV early protein and pp65 protein were detected using immunohistochemistry and indirect immunofluorescent; the virus titers of cultured supernatant neonatal rats'hippocampus nerve cells were determined; and HCMV particles in the nerve cells were observed using electron microscopy Results Characteristic CPE was observed on the first day of inoculation and this cytopathic change aggravated as inoculation time prolonged. HCMV early proteins were detected using immunohistochemistry,they are buffy particles in light microscope, and became more with the extension of time after infection.HCMV characteristic protein pp65 was detected using indirect immunofluorescent examination and the controls are negative.HCMV particles were observable in the cytoplasm and karyon of the nerve cells in the electron microscopy and the diameter of particles are 80～120 nm.Conclusion HCMV can infect neonatal murine hippocampus nerve cells in vitro and have certain proliferative ability. PART TWO HCMV Infection in first Trimester Influence on Synaptic Plasticity in Area DG of Offspring Rats HippocampusObjective To investigate the effect on offspring rats'dentate gyrus synaptic plasticity of mother's with HCMV primary infection during the first trimester. The study aimed at providing a scientific way to study the mechanism of learning disability caused by HCMV congenital infection. Methods HCMV (100TCID50 in 0.5ml/mice) were separately given to 8-week-old fertilized female SD rats on 4 gestation days in experimental group with intra-abdominal injections. The equal quantity supernate of HF cell were inoculated in mice of control group at the same times. The extracellular recordings experiment was performed in two groups of adult SD rats (postnatal days 60-90 days) to record the I/O, PPR, LTP/DP, and the pathological examination on hippocampus of rats were put after recording. Results①Input/output curves of the EPSP slope PS amplitude in area DG in experiment group was significantly depressed compared to control group(P<0.05).②Peak facilitation of Paired-pulse reactions (PPR) of the PS amplitude was 224.12±12.01 in control group and 175.16±14.79 in experiment group(F=12.12 ,P<0.01).③LTP of the EPSP slope and PS amplitude in area DG of the hippocampus is 137±4﹪(EPSP)and 225±11﹪(PS)in control group and 115±9﹪(EPSP)and163±7﹪(PS)in experiment group(EPSP:F=25.29,P<0.05;PS: F =74.33 P<0.05);④DP of the EPSP slope and PS amplitude86±3﹪(EPSP)and 85±2﹪(PS)in control group , 94±5﹪(EPSP)和93±4﹪(PS)in experiment group(EPSP:F=5.62,P<0.05;PS: F =4.22,P<0.05)Conclusion Synaptic response and synaptic transmission were depressed in area dentate gyrus and Paired-pulse reactions were depressed. HCMV first trimester infection impaired the LTP/DP measured on both EPSP slop and PS amplitude in area DG.HCMV first trimester infection can lead the impairments of synaptic plasticity on offspring rats.