| Objectives: In order to discuss whether the method of controlled ovarian hyperstimulation can affect the development of the nervous system of the offspring, we perform the technique in SD rats in this study, and further to study on the offspring’s ability of learning and memory, and to explore the possible protein expression in the hippocampus.Methods: 7 week old SD rats( 20 male and 20 female) are purchased one week ahead of time and fed according to levels of SPF animal feed specification. We observe their condition and divide randomly them into two groups, ten couples each group( 10 male and 10 female), until they adapt themselves to the new environment. Then received vaginal smear from 7:00 to 8:00 every morning. At 15:00 the same day after smear shows proestrus, one group is injected with 40 IU PMSG after random selection, and HCG of the same dosage in 48 hours. The other group is injected with 40 IU normal saline at the same timing. Female rats with PMSG and HCG are mated with male rats( one male and one female in each cage) and marked with Group COH as the study group, Female rats with normal saline are mated with male rats and marked with Group Controlled as control group.SD rats’ pregnancy lasts for 21 days, according to the SPF specification to continue feeding, and remove the male rats from the cages until rat offspring born. Then remove all female rats( including the generation of female rats,for the end of lactation) after the offspring rats in 1 month old. The offspring of every group rats are recorded at birth number and weight. Randomly taken out 16 offspring rats from Group COH and weighed,then marked with Group young COH, and 9 offspring rats from Group Controlled and weighed, then marked with Group young Controlled in 40 day old. Randomly taken out 14 offspring rats from Group COH and weighed, then marked with Group middle COH, and13 offspring rats from Group Controlled and weighed, then marked with Group middle Controlled in 8 month old. Morris water maze test is performed on the above four groups of rats, and monitored the ability of learning and memory.The offspring of rats with Morris water maze test after completion of intraperitoneal anesthesia, cardiac perfusion, decapitated operation, then are isolated the whole hippocampus used for Western blot detection. To explore the expression on the hippocampus may be related to CREB protein, To provide estimated reference for the development situation of the nervous system of human offspring were born with controlled ovarian hyperstimulation in their childhood, middle age.Results: The offspring of Group COH are born after 22-24 days, the amount is 15.8 ±2.9 and the weight is 6.44 ± 0.67. While the offspring of Group Controlled are born after45-60 days,the amount is 10.5 ± 3.1 and the weight is 7.83 ± 0.64. The amount of offspring rats in Group COH and Group Controlled shows statistical differences(p <0.05), while the weight shows no statistical differences, and the former has a downward trend.In the Group young COH, the weight of the offspring is 183.81 ± 12.46, The Group young Controlled is 189.78 ± 9.28, no differences are found between them. In the Group middle COH, the weight of the offspring is 320.21 ± 15.3, The Group middle Controlled is331.54 ± 14.48, no differences.In the Morris water maze spatial exploration task, through the day comparism of latency time, we can find no differences from the first day to the sixth day between Group young COH and Group young Controlled, while Group young COH( 14.90 ± 10.25) is significantly higher than Group young Controlled( 8.57 ± 2.80) on the seventh day.Obvious statistical differences are found between Group young COH( 35.13 ± 17.46) and Group middle COH( 46.74 ± 16.94) on the first day, while no differences from the second days to the seventh day.Statistical differences are found on the first day( 31.06 ± 11.66; 45.79 ± 17.04), the second day( 22.40 ± 15.60; 33.53 ± 15.77), the third day(21.79 ± 14.64; 29.48 ±17.75), the seventh day( 8.57 ± 2.80; 16.18 ± 9.55) between Group young Controlled and Group middle Controlled, while no differences are found on the fourth day, the fifth day, the sixth day.In Morris water maze working memory task, the comparison of latency time( 20.77 ±16.3; 14.87 ± 9.69) and swimming distance( 341.72 ± 315.35; 230.93 ± 173.03) both have Statistical differences between Group middle Controlled and Group young Controlled(P < 0.05).There are no significant differences in the expression of CREB protein in the hippocampus of rats after Morris water maze training.Conclusion: The offspring rats with controlled ovarian hyperstimulation demonstrates the same spatial learning and spatial memory ability in young and middle-aged period, compared with the normal pregnant rats in the same period. But more birth amount and low birth weight are the important factor for the spatial learning ability declining of juvenile offspring rat with controlled ovarian hyperstimulation. |
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