[Proteomic study on the damage of learning and memory ability of rat offspring caused by chronic stress during pregnancy].

Objective: To study the differential protein and signal pathway related to the impairment of learning and memory ability of offspring caused by chronic stress during pregnancy and explore the possible mechanism. Methods: From July to October 2019, sixteen SPF free female SD rats aged 80-90 days, weighing (200±20) g. Twelve SPF grade male SD rats aged 90-100 days, weighing (220±20) g. After a week of adaptive feeding, the female rats were randomly divided into control group and model group (8 rats in each group) , male rats were divided into control mating group (n=8) and model mating group (n=4) . Chronic unpredictable mild stress (CUMS) model was established and stimulated continuously for 21 days. One day before stress, the first, seventh, fourteenth and 21th day after stress, the blood was collected from the inner canthus vein of the female rats, and the content of corticosterone was determined. Morris water maze test was used to detect the spatial learning and memory ability of offspring rats. The morphological changes of hippocampus were observed by HE and Nissl staining. The proteomic correlation analysis of offspring rats' hippocampus was performed by isobaric tags for relative and absolute quantification (iTRAQ) technique. Results: Compared with the control group, the content of plasma corticosterone in the model group was significantly higher (F=7.717, P<0.05) , and the model was successfully established. In Morris water maze test, compared with the control offspring group, the escape latency was longer, the average swimming speed was lower, the number of crossing platform was less, and the target quadrant run was shorter in the model offspring group (P<0.05) . The pathological results showed that the morphology of cells in the hippocampal tissue of the model offspring group was irregular, the number of neurons was small, Nissl body was unevenly distributed, the volume was small and the number was small. Mass spectrometry analysis showed that a total of 5065 proteins were screened out in the two offspring groups, and 26 proteins were differentially expressed (P<0.05) , of which 19 proteins were up-regulated and 7 proteins were down regulated. The differential proteins were mainly involved in 23 biological processes, 14 cellular components and 9 molecular functions. Kyoto Encyclopedia of genes and genomes (KEGG) enrichment analysis showed that 57 pathways were enriched, of which 8 signaling pathways were significantly enriched (P<0.05) . There were 5 signaling pathways that might be involved in the impairment of learning and memory ability of offspring, including neuroactive ligand receptor interaction, cGMP-PKG signaling pathway, adhesion and connection, adhesion and connection FoxO signaling pathway and Notch signaling pathway, mainly including tyrosine protein kinase receptor, tyrosine kinase receptor and Notch signaling pathway, and α2A adrenergic receptor, cGMP dependent protein kinase and other differential proteins may be involved in the injury process. Conclusion: The damage of learning and memory ability of offspring may be caused by chronic stress during pregnancy rats. The enriched signal pathway and key differential proteins of proteomics may play an important role in the process of damage.

[Effects of chronic stress during pregnancy on composition and diversity of intestinal microbiota in female rats and offspring].

Objective: To investigate the effect of chronic stress of pregnant rats on the gut microbiota of female rats and offspring, and explore the role of intestinal microbiota in chronic stress during pregnancy. Methods: In November 2019, SPF-grade healthy adult SD rats were selected. 16 female rats were randomly divided into control group and model group, with 8 in each group; 12 male rats were randomly divided into model mating group (8) and control mating group (4) . A model of chronic unpredictable mild stress (CUMS) during pregnancy was established. Blood samples were collected from the iliac vein of the female rats 1 day before and 1, 7, and 14 days after the CUMS protocol, and measured for plasma corticosterone content by radioimmunoassay. After the stress was completed, fresh feces of the female rats were collected for testing. The offspring's fresh stool samples were collected on postnatal day 20 (PND20) , and they were divided into control offspring group and model offspring group samples. The sequence of 16S rRNAV3-V4 regions of microorganisms in the feces of offspring was determined by Illumina MiSeq technique; and the interaction between microbial community structure and diversity were analyzed. Results: The content of plasma corticosterone in the model group was higher than that in the control group on the 7th and 14th day of stress (P<0.05) . Compared with the control group, the Sobs index, Chao index, ACE index and Shannon index of the model group were decreased (P<0.05) . The number of unique species abundance (OTU) in the control group was 130, and 91 in the model group. The relative abundance of female Firmicutes in the control group (64.87%) was higher than that in the model group, and the relative abundance of Bacteroides (31.72%) was lower than that of the model group (46.35%) . The Sobs index, Chao index, ACE index, Simpson index and Shannon index of the control offspring group were higher than those of the model offspring group (P<0.05) . The number of unique OTUs in the model offspring group was 75, and 93 in the control offspring group. The relative abundance of Firmicutes (60.24%) in the control offspring group was higher than that of the model offspring group (52.95%) . Conclusion: Chronic stress during pregnancy can not only lead to the disorder of intestinal flora in female rats, but also lead to the change of intrauterine environment, thus affecting the diversity of intestinal flora in offspring.