Establishment of a Vaginal Atrophy Rat Model and its Application in Pharmacodynamic Evaluation

doi:10.12300/j.issn.1674-5817.2022.014

Abstract

Abstract:

Objective To establish an animal model suitable for screening vaginal preparations, administering the corresponding drugs, and evaluating biological indicators for monitoring drug treatment effects. Methods Bilateral ovariectomy (OVX) was used to establish the disease model of rat. The estrous cycle, uterine wet weight, and vaginal tissue morphology were observed from day 15 to day 21 after OVX to determine the optimal time for successful vaginal atrophy model after the OVX operation. Sprague-Dawley female rats were randomly divided into the following groups: normal group, sham group, model group, drug group 1, drug group 2, and solvent control group (n=10). Drug group 1, drug group 2, and solvent control group were treated with promestriene, Colpotrofin?, and solvent control for 14 days, respectively. Three days after the last administration, the body weight and uterus wet weight of the rats were measured, the histological morphology of the vagina was analyzed by HE staining, and estrogen receptors-α (ERα) expression was detected by immunohistochemistry. Results Twenty-one days after OVX, the vaginal atrophy model was established, which was suitable for the follow-up experiments. The change of estrous-cycle wasn't observed from day 17 to 21 after OVX. On 21 days after OVX, the vaginal epithelium thickness reduced (P<0.05), vaginal folds reduced, no squamous epithelium was observed, body weight increased (P<0.05), and uterine wet weight decreased (P<0.05). In drug group 1 and drug group 2, the symptoms of vaginal atrophy improved. Compared with the model group, the body weight of rats in drug group 1 and 2 decreased (P<0.05), the vaginal histomorphology improved, the expression of ERα protein in vaginal tissue up-regulated (P<0.05), and the ratio of uterine wet weight to body weight increased (P<0.01), but the endometrial thickness was not significantly thickened (P>0.05). Conclusion The rat OVX model is suitable for screening vaginal preparations. Vaginal histomorphology, endometrial thickness, and uterine/body weight ratio can be used as indicators to monitor drug efficacy.

Key words: Vaginal preparations, Vaginal atrophy, Ovariectomized rat model, Pharmacodynamic evaluation

CLC Number:

R-332

Liya YANG, Tao SONG, Jialin HE, Yiming GUO, Mingkang QI, Hanbi WANG, Huiping WANG. Establishment of a Vaginal Atrophy Rat Model and its Application in Pharmacodynamic Evaluation[J]. Laboratory Animal and Comparative Medicine, 2022, 42(6): 531-540.

Figures/Tables 7

Figure 1 Vaginal smears after ovariectomy （OVX） of rats in each group （Wright's staining， ×40）（A and B）and the proportion of the diestrus period （C）Note: A, regular changes in the estrous cycle were observed in the vaginal smears of the normal group (a–d show pre-estrous, estrous, post-estrous, and diestrus periods, respectively). B, vaginal smears after OVX in the model establishment group (a–d was 18, 19, 20, and 21 days after OVX, respectively, showing the diestrus period). C, the proportion of estrous/diestrus on days 7–21 after OVX in the model establishment group (21 rats), model group, drug group 1, drug group 2 and solvent control group (10 rats in each group) (n=61). Scale bars in all panels are 50 μm.

Figure 2 Body weight (A) and uterine wet weight/body weight (B) of rats from day 15–21 after ovariectomy (OVX)Note: A, weight changes of rats in the normal control and model establishment groups during days 15–21; B, changes in uterus wet weight/body weight at days 15–21 after OVX in the model establishment group. Daily number of rats n=3. *P<0.05, compared with the model establishment group.

Figure 3 Histopathological changes of vaginal in rats after ovariectomy (OVX) and the thickness of vaginal epitheliumNote：A, HE staining of vaginal tissues of rats in the model establishment and normal groups days 15–21 after OVX (scale bar is 100 μm); B, the thickness of the vaginal epithelium in the model establishment group days 15–21 after OVX (n=3, compared with 21 days after OVX, *P<0.05).

Figure 4 Body weight (A), uterine wet weight (B), and uterine wet weight/ body weight (C) of rats in each group after drug treatmentNote：Drug group 1, drug group 2, and solvent control group were treated with promestriene, Colpotrofin?, and solvent control for 14 days, respectively.In each group, n=10. ***P<0.001, compared with the sham group; #P<0.05, ##P<0.01, and ###P<0.001, compared with the model group.

Figure 5 Histopathological changes of uterus tissue（HE, ×2）(A) and thickness of the endometrium (B)Note：a, normal group; b, sham group; c, model group; d, solvent control group; e, drug group 1（promestriene）; f, drug group 2 （Colpotrofin?）. The scale bar of the panel is 1 mm. In each group, n=10. ***P<0.001, compared with the sham group.

Figure 6 Histopathological changes of vaginal tissue (HE, ×20)(A) and thickness of the vaginal epithelium (B)Note：a, normal group; b, sham group; c, model group; d, solvent control group; e, drug group 1（promestriene）; f, drug group 2 （Colpotrofin?）. The scale bar of the panel is 100 μm. *P<0.05, and **P<0.01, compared with the sham group; ###P<0.001, compared with the model group.

Figure 7 Immunohistochemistry (DAB, ×20）(A) and integral optical density (B) of ERα protein expression in rat vaginaNote：ERα, estrogen receptors-α. a, normal group; b, sham group; c, model group; d, solvent control group; e, drug group 1（promestriene）; f, drug group 2 （Colpotrofin?）. The scale bar of the panel is 20 μm. *P<0.05, compared with the sham group; #P<0.05, compared with the model group.

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