Effects of GW1929 on uterus, ovary and bone metabolism function in perimenopause rats

Abstract

This study was aimed to investigate the effect of GW1929, a novel peroxisome proliferator-activated receptors gamma (PPARγ) agonist, in perimenopause rats. Female Sprague-Dawley (SD) rats were treated with 4-vinylcyclohexene diepoxide (VCD) to induce perimenopause rat model. Then they were given GW1929 in low, middle and high dosage. Histopathology observation of uterus and ovary tissues was measured by hematoxylin and eosin staining. The levels of serum hormones, oxidative stress related factors, bone formation and bone metabolism associated factors in serum were detected by kits. Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) was employed to evaluate cell apoptosis. Furthermore, the expression of PPARγ and apoptosis associated proteins were measured by western blotting. The results revealed that there was no thickening of endometrium and no mature follicular development in ovaries of model group rats. GW1929 treatment recovered endometrial function with a tendency of thickening and there were mature follicle in the ovary. In addition, GW1929 increased the expression of PPARγ in both uterus and ovary tissues. The contents of estrogen (E2) were increased, whereas follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were decreased after being intervened with GW1929 in perimenopause rats. Concurrently, GW1929 reduced the levels of oxidative stress in a dose-dependent manner. Following treatment with GW1929, cell apoptosis in uterus and ovary tissues were attenuated, accompanied by a downregulation of Bax expression and an upregulation of Bcl-2 and cleaved caspase-3 expression. Moreover, In the GW1929-treated perimenopause rats, the levels of alkaline phosphatase (ALP), osteocalcin (OCN), osteopontin (OPN), bone alkaline phosphatase (BALP) and bone mineral density (BMD) were enhanced, while tartrate-resistant acid phosphatase (TRAP) was reduced. Taken together, we conclude that GW1929 could improve uterus, ovary and bone metabolism function in perimenopause rats, which is of great significance for the treatment of perimenopause.

Keywords: Perimenopause; bone metabolism; ovary; peroxisome proliferator-activated receptors gamma; uterus.

Figure 1

GW1929 improved the pathological changes of uterus tissues and ovarian tissues in perimenopause rats induced by VCD. The histopathology changes of (A) uterus tissues and (B) ovarian tissues were measured by H&E staining. Magnification ×200. VCD, 4-vinylcyclohexene diepoxide.

Figure 2

GW1929 upregulated the expression of PPARγ and affected the levels of serum hormones in perimenopause rat induced by VCD. The expression of PPARγ in (A) uterus tissues and (B) ovarian tissues were evaluated by Western blotting. The levels of (C) E2, (D) FSH and (E) LH in serum were detected by ELISA kits. Data were presented as mean ± SD and represented three separate experiments. ***P<0.001 vs. control; #P<0.05, ##P<0.01, ###P<0.001 vs. model. VCD, 4-vinylcyclohexene diepoxide; PPARγ, peroxisome proliferator-activated receptors gamma; E2, estrogen; FSH, follicle-stimulating hormone; LH, luteinizing hormone.

Figure 3

GW1929 alleviated the oxidative stress in perimenopause rat induced by VCD. The levels of (A) ROS, (B) CAT, (C) SOD and (D) GST were measured by kits. Data were presented as mean ± SD and represented three separate experiments. ***P<0.001 vs. control; #P<0.05, ##P<0.01, ###P<0.001 vs. model. VCD, 4-vinylcyclohexene diepoxide; ROS, reactive oxygen; CAT, catalase; SOD, superoxide dismutase; GST, glutathione S-transferase.

Figure 4

GW1929 inhibited apoptosis of uterus and ovarian cells in perimenopause rat induced by VCD. Photomicrographs of representative images of (A) uterus cell apoptosis and (B) ovarian cell apoptosis were assessed by TUNEL assay. Magnification ×100. VCD, 4-vinylcyclohexene diepoxide; TUNEL, Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling.

Figure 5

GW1929 reduced the expression of apoptosis-associated proteins in uterus tissues and ovarian tissues. Western blotting shows the expression levels of Bax, Bcl-2 and cleaved caspase-3 in (A) uterus tissues and (B) ovarian tissues. Data were presented as mean ± SD and represented three separate experiments. ***P<0.001 vs. control; #P<0.05, ##P<0.01, ###P<0.001 vs. model.

Figure 6

GW1929 regulated bone metabolic function in perimenopause rats induced by VCD. The levels of (A) ALP, (B) OCN, (C) OPN, (D) TALP and (E) TRAP in serum were measured by kits. (F) The levels of BMD were evaluated by dual-energy X-ray absorptiometry. Data were presented as mean ± SD and represented three separate experiments. ***P<0.001 vs. control; #P<0.05, ##P<0.01, ###P<0.001 vs. model. VCD, 4-vinylcyclohexene diepoxide; ALP, alkaline phosphatase; OCN, osteocalcin; OPN, osteopontin.