Establishment and Mechanism Study of a Primary Ovarian Insufficiency Mouse Model Using Lipopolysaccharide.

Si-Ji Lv,Lei Gan,Shu-Hui Hou,Jing Sun,Yun Ping Lim

doi:10.1155/2021/1781532

Abstract

This study is aimed at establishing a lipopolysaccharide- (LPS-) induced primary ovarian insufficiency (POI) mouse model and investigating the underlying mechanism. C57BL/6N female mice were intraperitoneally injected with low-dose LPS (0.5 mg/kg) once daily for 14 days, high-dose LPS (2.5 mg/kg) twice weekly for 2 weeks, or cyclophosphamide (CTX; 150 mg/kg) once weekly for 2 weeks. Ovarian function was assessed by measuring the length of estrous cycle, the number of primordial follicles, and the levels of serum hormones. Expression and production of interleukin 1β (IL-1β) were determined to evaluate ovarian inflammation. Histopathological examination was performed to examine ovarian fibrosis. TUNEL assay was carried out to evaluate granulosa cell apoptosis. Western blotting was performed to measure the levels of inflammation-, fibrosis-, and apoptosis-related proteins in the mouse ovaries. Like CTX, both low- and high-dose LPS significantly impaired ovarian functions in mice, as evidenced by extended lengths of estrous cycles, reduced counts of primordial follicles, and alterations in the levels of serum hormones. Also, LPS promoted granulosa cell apoptosis and ovarian fibrosis in mice. However, LPS but not CTX promoted IL-1β expression and production in mice. Moreover, LPS but not CTX enhanced TLR, p-p65, p65, and MyD88 expression in mouse ovaries, suggesting that LPS differs from CTX in triggering ovarian inflammation. In general, continuous low-dose LPS stimulation was less potent than high-dose LPS to affect the ovarian functions. In conclusion, LPS may induce ovarian inflammation, fibrosis, and granulosa cell apoptosis and can be used to establish a POI model in mice.

Highlights

Primary ovarian insufficiency (POI) refers to the cessation of ovarian function before the age of 40 years, with an incidence of approximately 1% by the age of 40 years and 0.1% by the age of 30 years
Both high-dose LPS and CTX markedly reduced the levels of serum anti-Müllerian hormone (AMH) and E2 while elevating the serum follicle-stimulating hormone (FSH) level in mice
Low-dose LPS was less potent than high-dose LPS in reducing the levels of serum AMH and E2 and had little influence on the serum FSH level in mice (Figure 1(c))

Summary

Introduction

Primary ovarian insufficiency (POI) refers to the cessation of ovarian function before the age of 40 years, with an incidence of approximately 1% by the age of 40 years and 0.1% by the age of 30 years. Owing to the similarity of the estrous cycle between female mice and humans, many studies have used POI mouse models to investigate the pathogenesis of POI and develop therapeutic modalities [9,10,11]. Chemotherapeutic agents, such as cyclophosphamide (CTX) and cisplatin, are widely used to establish POI animal models due to their irreversible cytotoxicity toward ovaries, including destroying oocytes and arousing follicular depletion [12,13,14]. Chemotherapy is one of the potential causes of POI, chemotherapeutic agent-induced POI may not simulate the pathophysiological conditions of POI

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