ABSTRACT
SUMMARY: A large body of evidence supports the protective role of the flavonol antioxidant compound quercetin in mammals. We tested the hypothesis that quercetin can protect against the hypothalamus-pituitary-gonadal (HPG) axis defect like a reduction in gonadotropins and testicular hormones and abnormal semen analysis induced by chronic unpredictable stress (CUS), possibly via the downregulation of oxidative stress (ROS) and p53-Bax-caspase-3 pathways. Rats were either exposed to a variety of unpredictable stressors daily before being sacrificed after 3 weeks (model group) or were treated with quercetin (50 mg/kg body weight/day) at the same time the CUS were induced (treated group). Harvested testicular tissues were stained with basic histological staining, and testis homogenates were assayed for the tumor suppressor p53, apoptosis regulator Bax, B-cell lymphoma 2 (Bcl-2), caspase-3, malondialdehyde (MDA), glutathione peroxidase (GPx), and superoxide dismutase (SOD). In addition, harvested epididymis tissues were used to assess semen analysis, and blood samples were assayed for the testicular hormone testosterone, the adrenal cortex hormone corticosterone, and the anterior pituitary gonadotropins, follicular stimulating hormone (FSH) and luteinizing hormone (LH). CUS induced profound testicular damage and significantly (p<0.05) induced p53, Bax, caspase-3, MDA, and corticosterone, which were significantly (p<0.05) inhibited by quercetin except corticosterone. Whereas, quercetin significantly (p<0.05) increased FSH, LH, testosterone, Bcl-2, GPx, and SOD levels that were inhibited by CUS. In addition, CUS induced oligozoospermia, asthenozoospermia, and teratozoospermia, which were significantly (p<0.05) protected by quercetin. Thus, Quercetin protects against CUS-induced HPG defects in rats, which is associated with the inhibition of ROS-p53-Bax-caspase-3 axis.
RESUMEN: El papel protector del compuesto antioxidante flavonol quercetina en los mamíferos ha sido ampliamente reportado. Probamos la hipótesis que la quercetina puede proteger contra el defecto del eje hipotálamo-hipofisiario- gonadal (HHG) como una reducción de gonadotropinas y hormonas testiculares y análisis de semen anormal inducido por estrés crónico impredecible (ECI), posiblemente a través de la regulación reducida del estrés oxidativo (REO) y las vías p53- Bax-caspasa-3. Las ratas fueron expuestas a una variedad de fac- tores estresantes impredecibles diariamente antes de ser sacrificadas después de 3 semanas (grupo modelo) o fueron tratadas con quercetina (50 mg / kg de peso corporal / día) al mismo tiempo que se indujo la ECI (grupo tratado). Los tejidos testiculares fueron teñidos con tinción histológica básica y los homogeneizados de testículo se analizaron para determinar el supresor de tumores p53, el regulador de apoptosis Bax, el linfoma de células B 2 (Bcl-2), la caspasa-3, el malondialdehído (MDA), la glutatión peroxidasa (GPx) y superóxido dismutasa (SOD). Además, se utilizaron tejidos del epidídimo recolectados para evaluar el análisis de semen y se analizaron muestras de sangre para determinar la hormona testicular testosterona, la hormona corticosterona de la corteza suprarrenal y las gonadotropinas de la hipófisis anterior, la hormona estimulante folicular (FSH) y la hormona luteinizante (LH). El ECI indujo daño testicular importante e indujo significativamente niveles de (p <0,05) p53, Bax, caspasa-3, MDA y corticosterona, que fueron inhibidos (p <0,05) por la quercetina. La quercetina aumentó significativamente (p <0,05) los niveles de FSH, LH, testosterona, Bcl-2, GPx y SOD que fueron inhibidos por ECI. Además, ECI indujo oligozoospermia, astenozoospermia y teratozoospermia, protegidos de manera significativa (p <0,05) por la quercetina. Por lo tanto, la quercetina protege contra los defectos de HHG inducidos por ECI en ratas, lo que está asociado con la inhibición del eje ROS-p53-Bax-caspasa-3.
Subject(s)
Animals , Male , Rats , Quercetin/administration & dosage , Stress, Physiological , Testicular Diseases/etiology , Testis/drug effects , Antioxidants/administration & dosage , Testis/injuries , Chronic Disease , Tumor Suppressor Protein p53/antagonists & inhibitors , Reactive Oxygen Species/antagonists & inhibitors , Rats, Wistar , Apoptosis/drug effects , Disease Models, Animal , bcl-2-Associated X Protein/antagonists & inhibitors , Caspase 3/drug effects , Hypothalamic-Pituitary-Gonadal Axis/drug effectsABSTRACT
The p53 protein is well-known for its tumour suppressor function. The p53-MDM2 negative feedback loop constitutes the core module of a network of regulatory interactions activated under cellular stress. In normal cells, the level of p53 proteins is kept low by MDM2, i.e. MDM2 negatively regulates the activity of p53. In the case of DNA damage, the p53-mediated pathways are activated leading to cell cycle arrest and repair of the DNA. If repair is not possible due to excessive damage, the p53-mediated apoptotic pathway is activated bringing about cell death. In this paper, we give an overview of our studies on the p53-MDM2 module and the associated pathways from a systems biology perspective.We discuss a number of key predictions, related to some specific aspects of cell cycle arrest and cell death, which could be tested in experiments.