Low-dose spironolactone ameliorates adipose tissue inflammation and apoptosis in letrozole-induced PCOS rat model

Abstract

Background of study: Globally, many reproductive aged women are affected by polycystic ovarian syndrome (PCOS), which is a common endocrine and metabolic disorder that is linked with adipose dysfunction and chronic low-grade inflammation. Spironolactone (SPL), a mineralocorticoid receptor blocker has been documented as a metabolic modulator. However, its immunomodulatory effect in PCOS is unknown. Therefore, the present study hypothesized that SPL would ameliorate adipose dysfunction and inflammation in experimental PCOS animals.

Materials and methods: Female Wistar rats that were 8 weeks old were allocated into three groups. Group 1 received vehicle (distilled water; p.o.), group 2 received letrozole (1 mg/kg; p.o.) and group 3 received letrozole plus SPL (0.25 mg/kg, p.o.). The administration was performed once daily for 21 days.

Results: The experimental PCOS animals showed insulin resistance, hyperinsulinemia and hyperandrogenism as well as oxidative stress and elevated inflammatory biomarkers (NF-kB/TNF-/IL-6) as well as a significant decrease in triglycerides, total cholesterol, free fatty acids, GSH and G6PD in the adipose tissue of PCOS animals. In addition, immunohistochemical assessment of adipose tissue showed significant expression of BAX and inflammasome, indicating apoptosis and inflammation compared to control animals. Nevertheless, administration of SPL attenuated these perturbations.

Conclusion: Altogether, the present study suggests that low-dose spironolactone confers protection against adipose dysfunction in experimental PCOS animals by attenuating inflammation, oxidative stress and cellular apoptosis.

Keywords: Adipose tissue; Inflammation; Oxidative stress; PCOS; Spironolactone.

Fig. 1

Effects of low-dose SPL on HOMA-IR (a), plasma insulin (b) and testosterone (c) in experimentally induced PCOS rat model. Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL), Homeostatic Model of Assessment of Insulin Resistance (HOMA-IR)

Fig. 2

Effects of low-dose SPL on adipose TG (a) TC (b) and FFA (c) in experimentally induced PCOS rat model. Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL), Triglycerides (TG), Total cholesterol (TC), Free fatty acids (FFA)

Fig. 3

Effects of low-dose SPL on adipose MDA (a) GSH (b) and G6PD (c) in experimentally induced PCOS rat model. Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL), Malondialdehyde (MDA), Reduced glutathione (GSH), Glucose-6 phosphate dehydrogenase (G6PD)

Fig. 4

Effects of low-dose SPL on adipose NF-kB (a), TNF- (b) and IL-6 (c) in experimentally induced PCOS rat model. Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL), Nuclear factor-kappa B (NF-kB), Tumor necrosis factor- (TNF-)

Fig. 5

Effects of low-dose SPL on the immunohistochemistry of adipose tissue in experimentally induced PCOS rat model using BAX antibody. Scale bar: 51 μm. Small images (X200); Big images (X800). Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL)

Fig. 6

Effects of low-dose SPL on the immunohistochemistry of adipose tissue in experimentally induced PCOS rat model using NLRP3 inflammasome antibody. Scale bar: 51 μm; Small images (X200); Big images (X800). Data are expressed as S.D, n = 6. (*p < 0.05 vs. CTR, #p < 0.05 vs. LET). Control (CTR), Letrozole (LET), Spironolactone (SPL)