[Animal modeling] - Establishment and applicability evaluation of animal model of pelvic organ prolapse

  Objective To establish a rat model that can reflect the similar pathological changes of sacral ligaments in patients with pelvic organ prolapse, and to explore the effects of increasing the intensity of birth injury and simulating menopause on the pathology of sacral ligaments in rats, so as to provide an experimental basis for further research.

  Methods Sixty adult SPF grade SD female rats weighing about 300 g were selected, 45 of which had no reproductive history. They were randomly divided into blank control group (A), simulated menopause group (B), simulated birth injury+simulated menopause group (C), and 15 rats who had delivered for three consecutive times were divided into birth injury+simulated birth injury+simulated menopause group (D). Group A drank and ate normally, group B underwent double oophorectomy, group C underwent simulated labor injury and bilateral ovariectomy to simulate menopause, and group D underwent bilateral ovariectomy to simulate menopause after 2 times of simulated labor injury on the basis of 3 consecutive deliveries, all of which were routinely raised for 8 to 10 weeks. Eight rats in each group were randomly selected to observe the changes of genital appearance and genital hiatus in each group; Immunohistochemical method was used to observe and evaluate type I and type III collagen (COL1A1, COL3A1) and transforming growth factor of the anterior vaginal wall β- 3(TGF β- 3) Integrated optical density change. Determination of COL1A1, COL3A1 and TGF in sacral ligament tissue by RT-PCR β- 3 mRNA expression level.

  Results After the model was established, the diameter of vaginal hiatus in group D was more than 2 mm larger than that in the control group. There was no obvious prolapse phenotype in each group. Group D showed mild perineal body abnormalities; The expression of COL1A1 in the anterior vaginal wall of rats in group D was significantly lower than that in group A (P<0.05), TGF β- 3 Compared with group A, the relative expression level of group C and group D was significantly higher than that of group A (P<0.05); The expression of COLIA1 and COL3A1 in sacral ligament of rats in group D was significantly lower than that in group A (P<0.05), TGF β- 3 Compared with group A, the relative expression amount of group C and group D was significantly higher than that of group A (P<0.05).

  Conclusion The genital prolapse phenotype of the rat model after modeling is not significant, such as the study of phenotypic changes in this model is not appropriate; This model can be used as an animal model to study the pathophysiological changes of the sacral ligament of POP, but it cannot be determined whether the mechanical properties of human and rat sacral ligaments are similar. It is necessary to select the most appropriate animal model based on the respective advantages and disadvantages of various animals and the practical research problems to be solved.