雌性侏儒症大鼠繁殖性能初探

Preliminary Probing for Reproductive Performance in Female Dwarfism Rats

目的初步探讨自发侏儒症Wistar大鼠(spontaneous dwarfism Wistar rat,SDWR)的繁殖性能及其低下的原因。方法SDWR大鼠组和Wistar大鼠对照组分别选12周龄雌鼠及雄鼠各50只,按1♀∶1♂进行交配,测定SDWR、Wistar大鼠第1~4胎妊娠率、窝产仔数、初生窝重、离乳率、离乳重;选取8周龄雌性SDWR大鼠和5周龄雌性Wistar大鼠各20只,阴道脱落细胞涂片法评估两组大鼠性成熟期及动情周期;6~8周龄雌性SDWR及Wistar大鼠各20只,分别采用200 U/kg、300 U/kg、400 U/kg剂量的孕马血清促性腺激素+人绒毛膜促性腺激素腹腔注射进行超排卵实验,比较促排卵效果;6~8周龄Wistar、SDWR及SDWR超排组各20只,通过HE染色分析比较卵巢组织形态改变。结果SDWR组1~4胎妊娠率、窝产仔数、初生窝重、离乳重及离乳率显著低于Wistar组(P<0.05);SDWR组性成熟[(12.15±0.81)周]比Wistar[(8.05±0.76)周]明显推迟;Wistar组保持4~5 d规律的动情周期,而SDWR出现动情周期延长及紊乱,7~8d一个周期,动情期缩短,动情间期延长;超排结果显示:SDWR组卵细胞数量均显著少于Wistar组(P<0.01)。卵巢组织HE染色结果显示,Wistar组卵巢各级卵泡生长活跃,颗粒细胞及黄体结构正常,而SDWR组卵巢总卵泡及各级卵泡数量均明显减少,卵巢皮质纤维化,颗粒细胞排列紊乱。结论侏儒症SDWR大鼠繁殖率低下可能与性成熟晚、动情周期延长及紊乱、卵巢功能减退有关。

Objective To probe the causes of low reproductive performance in spontaneous dwarfism Wistar rats(SDWR).Methods A Wistar rat control group and a SDWR group both included 50 female and 50 male rats aged 12 weeks respectively,and were mated 1∶1(male to female);the pregnancy rate,litter size,litter birth weight,weaning rate and weaning weight of the SDWR and Wistar rats were measured from the first parity to the fourth.Twenty female SDWR aged 8 weeks and 20 female Wistar rats aged 5 weeks were selected respectively to evaluate puberty and estrous cycle by vaginal cytology.Twenty female SDWR and 20 female Wistar rats aged 6-8 weeks were respectively injected intraperitoneally with 200 U/kg,300 U/kg and 400 U/kg of pregnant mare serum gonadotropin(PMSG)plus human chorionic gonadotropin(hCG)for superovulation,and the ovulation induction effects.Twenty Wistar,20 SDWR and 20 SDWR superovulation rats aged 6-8 weeks were compared in morphological changes of ovarian tissue by HE staining.Results The pregnancy rate,litter size,litter birth weight,weaning weight and weaning rate of the first parity to the fourth of the SDWR group were significantly lower than those of the Wistar group(P<0.05).In the SDWR group,sexual maturation[(12.15±0.81)weeks]was significantly delayed compared with the Wistar group[(8.05±0.76)weeks].The Wistar group maintained a regular estrous cycle of 4-5 days,while the SDWR group showed an extended and disordered estrous cycle of 7-8 days,shortened estrous and extended metestrus.The results of superovulation test showed that the number of eggs in the SDWR group was significantly lower than that in the Wistar group(P<0.01).The results of HE staining of ovarian tissue showed that in the Wistar group,follicles at all levels were growing actively,and granular cells and corpus luteum structure were normal;while in the SDWR group,the number of total ovarian follicles and follicles at all levels were significantly reduced,and granular cells was disarranged.Conclusion The low reproductive rate of SDWR may be related to delayed sexual maturity,prolonged and disordered estrous cycle,and ovarian dysfunction.