Quercetin activates autophagy to protect rats ovarian granulosa cells from H2O2-induced aging and injury

Establishment of a mouse model of ovarian oxidative stress induced by hydrogen peroxide

Introduction

Oxidative stress, resulting from environmental changes, significantly affects female fertility. Developing a mouse model to study oxidative stress lays the groundwork for research into human reproductive health and livestock fertility.

Materials and methods

In this study, we established and evaluated an oxidative stress model by administering hydrogen peroxide (H2O2) to mice. ICR mice of similar age (7-8 weeks old) and average body weight (31.58 ± 1.12 g) were randomly assigned to four groups (A, B, C, and D). Group A served as the control and was injected with a saline solution, while groups B, C, and D received saline solutions containing 0.75%, 1.50%, and 3.0% H2O2, respectively, over one week. We measured the body weights of all mice before and after the experimental period.

Results and discussion

Our findings showed that the average body weight of mice in groups A and B increased, while groups C and D experienced weight loss. Group C showed a significantly lower average weight gain compared to groups A and B, and group D exhibited an even more pronounced reduction in weight gain. Although group D had a high mortality rate, there was no significant difference in mortality rates among groups B, C, and D. Serum malondialdehyde (MDA) content increased with higher concentrations of H2O2, with a significant difference noted between groups C and A. Catalase (CAT) activity in group B was significantly higher than in group A, while superoxide dismutase (SOD) activity in group C was notably elevated compared to groups A and B. Conversely, glutathione peroxidase (GSH-Px) activity in group C was significantly lower than in both group A and group B. Hematoxylin and eosin (HE) staining revealed changes in ovarian morphology and follicle dynamics. The percentage of atretic follicles in group C was significantly higher than in the control group, and group D had a significantly lower total number of healthy follicles compared to the untreated group. Increased H2O2 content resulted in a reduction of ovary size and an irregular appearance in group D.

Conclusion

Based on our findings, treatment with 1.50% H2O2 effectively established an oxidative stress model in mice within 1 week. This model serves as a valuable reference for future clinical studies on oxidative stress and reproductive disorders in female animals and humans.

Quercetin ameliorates oxidative stress-induced apoptosis of granulosa cells in dairy cow follicular cysts by activating autophagy via the SIRT1/ROS/AMPK signaling pathway

BACKGROUND

Follicular cysts contribute significantly to reproductive loss in high-yield dairy cows. This results from the death of follicular granulosa cells (GCs) caused by oxidative stress. Quercetin is known to have significant antioxidant and anti-apoptotic effects. However, the effect of quercetin on follicular cysts has yet been elucidated. Therefore, this study aimed to explore the anti-oxidant and anti-apoptosis effects and potential molecular mechanisms of quercetin in H2O2-induced primary cow GCs and 3-nitropropionic acid (3-NPA)-induced mouse model of oxidative stress and thus treat ovarian cysts in dairy cows.

RESULTS

In this study, compared with estrus cows, cows with follicular cysts showed heightened levels of oxidative stress and increased follicular cell apoptosis, while autophagy levels were reduced. A model of oxidative stress was induced in vitro by H2O2 and showed significant increases in apoptosis together with reduced autophagy. These effects were significantly ameliorated by quercetin. Effects similar to those of quercetin were observed after treatment of cells with the reactive oxygen species (ROS) inhibitor N-acetylcysteine (NAC). Further investigations using chloroquine (autophagy inhibitor), rapamycin (autophagy activator), selisistat (SIRT1 inhibitor), and compound C (AMPK inhibitor) showed that chloroquine counteracted the effects of quercetin on oxidative stress-induced apoptosis, while rapamycin had the same effect as quercetin. In addition, the SIRT1/AMPK pathway inhibitors antagonized quercetin-mediated mitigation of the effects of oxidative stress on increased apoptosis and reduced autophagy. Consistent with the results in vitro, in mouse ovarian oxidative stress model induced by 3-NPA, quercetin activated autophagy through the SIRT1/AMPK signaling pathway, while alleviating oxidative stress damage and inhibiting apoptosis in mouse ovaries.

CONCLUSIONS

These findings indicate that quercetin can inhibit apoptosis in GCs and restore ovarian function by activating autophagy through the SIRT1/ROS/AMPK signaling pathway, suggesting a new direction for the treatment of ovarian follicular cysts in high-yield dairy cows.

The role of cellular senescence in ovarian aging

This review explores the relationship between ovarian aging and senescent cell accumulation, as well as the efficacy of senolytics to improve reproductive longevity. Reproductive longevity is determined by the age-associated decline in ovarian reserve, resulting in reduced fertility and eventually menopause. Cellular senescence is a state of permanent cell cycle arrest and resistance to apoptosis. Senescent cells accumulate in several tissues with advancing age, thereby promoting chronic inflammation and age-related diseases. Ovaries also appear to accumulate senescent cells with age, which might contribute to aging of the reproductive system and whole organism through SASP production. Importantly, senolytic drugs can eliminate senescent cells and may present a potential intervention to mitigate ovarian aging. Herein, we review the current literature related to the efficacy of senolytic drugs for extending the reproductive window in mice.

Lipid nanoparticles of quercetin (QU-Lip) alleviated pancreatic microenvironment in diabetic male rats: The interplay between oxidative stress - unfolded protein response (UPR) - autophagy, and their regulatory miRNA

BACKGROUND

Autophagy is a well-preserved mechanism essential in minimizing endoplasmic reticulum stress (ER)-related cell death. Defects in β-cell autophagy have been linked to type 1 diabetes, particularly deficits in the secretion of insulin, boosting ER stress sensitivity and possibly promoting pancreatic β-cell death. Quercetin (QU) is a potent antioxidant and anti-diabetic flavonoid with low bioavailability, and the precise mechanism of its anti-diabetic activity is still unknown. Aim This study aimed to design an improved bioavailable form of QU (liposomes) and examine the impact of its treatment on the alleviation of type 1 diabetes induced by STZ in rats.

METHODS

Seventy SD rats were allocated into seven equal groups 10 rats of each: control, STZ, STZ + 3-MA, STZ + QU-Lip, and STZ + 3-MA + QU-Lip. Fasting blood glucose, insulin, c-peptide, serum IL-6, TNF-α, pancreatic oxidative stress, TRAF-6, autophagy, endoplasmic reticulum stress (ER stress) markers expression and their regulatory microRNA (miRNA) were performed. As well as, docking analysis for the quercetin, ER stress, and autophagy were done. Finally, the histopathological and immunohistochemical analysis were conducted.

SIGNIFICANCE

QU-Lip significantly decreased glucose levels, oxidative, and inflammatory markers in the pancreas. It also significantly downregulated the expression of ER stress and upregulated autophagic-related markers. Furthermore, QU-Lip significantly ameliorated the expression of several MicroRNAs, which both control autophagy and ER stress signaling pathways. However, the improvement of STZ-diabetic rats was abolished upon combination with an autophagy inhibitor (3-MA). The findings suggest that QU-Lip has therapeutic promise in treating type 1 diabetes by modulating ER stress and autophagy via an epigenetic mechanism.