scholarly journals Nitric Oxide Alleviated High Salt–Induced Cardiomyocyte Apoptosis and Autophagy Independent of Blood Pressure in Rats

2021 ◽  
Vol 9 ◽  
Author(s):  
Yong Li ◽  
Xiaoguang Wu ◽  
Yukang Mao ◽  
Chi Liu ◽  
Yiting Wu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Caspase 3 ◽  
High Salt ◽  
Beclin 1 ◽  
Cardiomyocyte Apoptosis ◽  
Neonatal Rat ◽  
Caspase 8 ◽  
H9c2 Cells ◽  
Cardiac Damage

The present study aimed to explore whether high-salt diet (HSD) could cause cardiac damage independent of blood pressure, and whether nitric oxide (NO) could alleviate high-salt–induced cardiomyocyte apoptosis and autophagy in rats. The rats received 8% HSD in vivo. H9C2 cells or primary neonatal rat cardiomyocytes (NRCM) were treated with sodium chloride (NaCl) in vitro. The levels of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1 and autophagy related 7 (ATG7) were increased in the heart of HSD rats with hypertension (HTN), and in hypertension-prone (HP) and hypertension-resistant (HR) rats. Middle and high doses (50 and 100 mM) of NaCl increased the level of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in H9C2 cells and NRCM. The endothelial NO synthase (eNOS) level was increased, but p-eNOS level was reduced in the heart of HSD rats and H9C2 cells treated with 100 mM NaCl. The level of NO was reduced in the serum and heart of HSD rats. NO donor sodium nitroprusside (SNP) reversed the increases of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2 induced by NaCl (100 mM) in H9C2 cells and NRCM. SNP treatment attenuated the increases of cleaved-caspase 3/caspase 3, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in the heart, but had no effect on the blood pressure of HSD rats with HR. These results demonstrated that HSD enhanced cardiac damage independently of blood pressure. Exogenous NO supplementarity could alleviate the high salt–induced apoptosis and autophagy in cardiomyocytes.

scholarly journals The MicroRNA-210/Casp8ap2 Pathway Alleviates Hypoxia-Induced Injury in Myocardial Cells by Regulating Apoptosis and Autophagy

2020 ◽  
Vol 23 (6) ◽  
pp. E797-E802
Author(s):  
Kunsheng Li ◽  
Jun Pan ◽  
Qiuchang Li ◽  
Shiliang Li ◽  
Kai Li ◽  
...  
Keyword(s):  
Myocardial Injury ◽  
Caspase 3 ◽  
Transfection Efficiency ◽  
Beclin 1 ◽  
Caspase 8 ◽  
H9c2 Cells ◽  
Myocardial Cells ◽  
Western Blot Assay ◽  
H9c2 Cardiomyocytes ◽  
Associated Proteins

Aim: This study was conducted to investigate the role of the miR-210/Caspase8ap2 pathway in apoptosis and autophagy in hypoxic myocardial cells. Methods: The miR-control, miR-210 mimic, and miR-210 inhibitor were transfected into rat myocardial H9C2 cells. The transfection efficiency of exogenous miR-210 was determined by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). H9C2 cells were then treated with CoCl2 for 24, 48, and 72 h to generate a myocardial injury model. The apoptosis of H9C2 cells was assessed by flow cytometry. Additionally, a western blot assay was used to determine the expression of the autophagy-associated proteins light chain 3 (LC3), p62 and Beclin-1, and apoptosis-associated proteins Caspase8ap2, cleaved caspase 8, and cleaved caspase 3. Results: We determined that a 48 h hypoxia treatment duration in H9C2 cardiomyocytes induced myocardial injury. Additionally, the overexpression of miR-210 significantly inhibited cell apoptosis. MiR-210 suppressed autophagy by upregulating p62 and downregulating LC3II/I in hypoxic H9C2 cells. Caspase8ap2 was a putative target of miR-210, miR-210 mediated apoptosis, and autophagy of H9C2 cells via suppressing Caspase8ap2. Furthermore, the expression of caspase 8, caspase 3, and Beclin-1 were decreased in response to miR-210. Conclusion: miR-210 exhibits anti-apoptosis and anti-autophagy effects, which alleviate myocardial injury in response to hypoxia.

scholarly journals Protective Effects of Shenfuyixin Granule on H2O2-Induced Apoptosis in Neonatal Rat Cardiomyocytes

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xinlu Wang ◽  
Xuanxuan Hao ◽  
Youping Wang ◽  
Bin Li ◽  
Lin Cui ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Caspase 3 ◽  
Neonatal Rat ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Rat Cardiomyocytes ◽  
Expression Levels ◽  
Apoptosis Rate ◽  
Neonatal Rat Cardiomyocytes ◽  
Mitochondrion Membrane Potential

Shenfuyixin granule (SFYXG, i.e., Xinshuaikang granule) is a prescription, commonly used in the clinical experience, which plays a significant role in the treatment of heart failure. The purpose of this present research was to investigate the protective effect of SFYXG, and the mechanism about anti-H2O2-induced oxidative stress and apoptosis in the neonatal rat cardiomyocytes. Myocardial cells, as is well known, were divided into 4 groups: normal, model, SFYXG, and coenzyme Q10 group, respectively. Cells viability was determined by MTT assay. Flow cytometry and AO/EB staining were implemented to test the apoptosis rate and intracellular reactive oxygen species (ROS) level. Mitochondrion membrane potential (MMP) was evaluated by JC-1 fluorescence probe method. The myocardial ultrastructure of mitochondrion was measured by electron microscope. The related mRNA expression levels of Bax, Bcl-2, Caspase-3, caspase-8, and caspase-9 were detected by real-time polymerase chain reaction (PCR). Also, the expression levels of Bax and Bcl-2 protein were detected by Western blot, and the expression levels of caspase-3, caspase-8, and caspase-9 protein were tested by caspase-Glo®3 Assay, caspase-Glo®8 Assay, and caspase-Glo®9 Assay, respectively. GAPDH was used as the internal reference gene/protein. The results revealed that SFYXG (0.5 mg/ml) raised the viability of myocardial cell, weakened the apoptosis rate and ROS level, corrected the mitochondrion membrane potential stability, and improved cell morphology and ultrastructure of myocardial mitochondrion. Furthermore, SFYXG upregulated the antiapoptosis gene of Bcl-2, but downregulated the proapoptosis genes of Bax, caspase-3, and caspase-9. In conclusion, SFYXG could appear to attenuate myocardial injury by its antioxidative and antiapoptosis effect.

scholarly journals Centella asiatica (L.) Urb. Prevents Hypertension and Protects the Heart in Chronic Nitric Oxide Deficiency Rat Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Mohd Khairulanwar Bunaim ◽  
Yusof Kamisah ◽  
Mohd Noor Mohd Mustazil ◽  
Japar Sidik Fadhlullah Zuhair ◽  
Abdul Hamid Juliana ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Brain Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Rat Model ◽  
Antioxidant Properties ◽  
Centella Asiatica ◽  
Sprague Dawley ◽  
Cardiac Damage ◽  
Ace Activity

Background: Hypertension is a major risk factor for cardiovascular disease (CVD), which is the number one cause of global mortality. The potential use of natural products to alleviate high blood pressure has been demonstrated to exert a cardioprotective effect. Centella asiatica (L.) Urb. belongs to the plant family Apiaceae (Umbelliferae). It contains a high amount of triterpenoid and flavonoid that have antioxidant properties and are involved in the renin-angiotensin-aldosterone system which is an important hormonal system for blood pressure regulation.Objective: This study aimed to investigate the effects of C. asiatica ethanolic extract on blood pressure and heart in a hypertensive rat model, which was induced using oral N(G)-nitro-l-arginine methyl ester (l-NAME).Methods: Male Sprague-Dawley rats were divided into five groups and were given different treatments for 8 weeks. Group 1 only received deionized water. Groups 2, 4, and 5 were given l-NAME (40 mg/kg, orally). Groups 4 and 5 concurrently received C. asiatica extract (500 mg/kg, orally) and captopril (5 mg/kg, orally), respectively. Group 3 only received C. asiatica extract (500 mg/kg body weight, orally). Systolic blood pressure (SBP) was measured at weeks 0, 4, and 8, while serum nitric oxide (NO) was measured at weeks 0 and 8. At necropsy, cardiac and aortic malondialdehyde (MDA) contents, cardiac angiotensin-converting enzyme (ACE) activity, and serum level of brain natriuretic peptide (BNP) were measured.Results: After 8 weeks, the administrations of C. asiatica extract and captopril showed significant (p < 0.05) effects on preventing the elevation of SBP, reducing the serum nitric oxide level, as well as increasing the cardiac and aortic MDA content, cardiac ACE activity, and serum brain natriuretic peptide level.Conclusion:C. asiatica extract can prevent the development of hypertension and cardiac damage induced by l-NAME, and these effects were comparable to captopril.

Abstract P173: Role Of Potassium Intake On Hypertensive Cardiovascular Damage In Apolipoproteine-deficient Mice Under Normal And High Salt Conditions

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Mina Yakoub ◽  
Denada Arifaj ◽  
Doron Argov ◽  
Masudur Rahman ◽  
Sebastian Temme ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Hypertrophy ◽  
Aortic Arch ◽  
High Salt ◽  
Ang Ii ◽  
Cardiac Damage ◽  
High Sodium ◽  
Cardiovascular Damage ◽  
High K ◽  
Deficient Mice

Reduced potassium (k+) intake has been linked to cardiovascular diseases. The underlying mechanisms remain unknown. Here, we investigate the effect of low (0%), normal (0.5%) and high K+ (5%) diet on the development of atherosclerosis and hypertensive cardiac damage. To induce atherosclerosis, apolipoprotein-deficient mice were infused with angiotensin (Ang) II (500ng/kg/min) for 28 days. Potassium treatment was initiated 2 weeks before Ang II infusion. Cardiac function was assessed by MRI. Levels of K+ in the serum and urine were significantly different between groups. The Ang II infused mice from the K+ low group had significantly higher atherosclerotic plaques in the aortic arch (21±3%) compared to K+ high (10±2%) and K+ normal (11±2%) groups. The atherosclerosis development was blood pressure independent since no differences in blood pressure between the groups were observed. Although heart to body-weight ratio did not differ between three groups, K+ low diet was associated with a lower ejection fraction rate and increased mRNA expression levels of cardiac ANP, BNP, collagen and fibronectin compared to the K+ normal and K+ high group. After Ang II infusion, assessment of aldosterone levels in urine showed significant higher aldosterone levels in the high K+ (214±72ng/24h) compared to normal K+ (26±6ng/24h) and low K+ (18±4ng/24h) groups. Aldosterone induced cardiovascular damage is known to be aggravated by sodium. To, evaluate whether high sodium diet unmask aldosterone mediated cardiovascular damage in the high K+ group, mice fed a high or normal K+ diet were additionally treated with high sodium (1% NaCl) in the drinking water. During Ang II treatment, high salt diet accelerated atherosclerosis in the aortic arch of both groups but no differences were observed between the high K+ high/high Na+ (41±7%) and normal K+/high Na+ (49±2%) group. In contrast, high K+/high Na+ group have significantly more severe cardiac hypertrophy compared to normal K+ high Na+ group (8.9±0.7 vs 6.4±0.7mg/g). These results were confirmed by MRI. K+ deficient diet induces atherosclerosis and cardiac damage during Ang II induced hypertension. K+ enriched diet exacerbates cardiac hypertrophy only under high Na+ conditions most likely in an aldosterone-dependent mechanism.

Lipid emulsion attenuates apoptosis induced by a toxic dose of bupivacaine in H9c2 rat cardiomyoblast cells

2016 ◽  
Vol 35 (9) ◽  
pp. 929-937 ◽  
Author(s):  
S-H Ok ◽  
J Yu ◽  
Y Lee ◽  
H Cho ◽  
I-W Shin ◽  
...  
Keyword(s):  
Cell Viability ◽  
Lipid Emulsion ◽  
Caspase 3 ◽  
In Vitro Study ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Caspase 8 ◽  
Lipid Solubility ◽  
H9c2 Cells ◽  
Toxic Dose

The goal of this in vitro study was to investigate the effect of lipid emulsion on apoptosis induced by a toxic dose of bupivacaine (BPV) in H9c2 rat cardiomyoblast cell lines. The effect of lipid emulsion on the decreased cell viability and count induced by BPV or mepivacaine (MPV) in the H9c2 cells was assessed using an 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide assay or a cell count assay. The effect of BPV or lipid emulsion combined with BPV on cleaved caspase 3, caspase 8, and Bax in H9c2 cells was investigated using Western blotting. A terminal deoxynucleotidyl transferase dUTP2′-deoxyuridine 5′-triphosphate nick end-labeling (TUNEL) assay was performed to detect apoptosis of H9c2 cells treated with BPV alone or lipid emulsion combined with BPV. The magnitude of lipid emulsion-mediated attenuation of decreased cell viability induced by BPV was higher than that of lipid emulsion-mediated attenuation of decreased cell viability induced by MPV. Lipid emulsion attenuated the increases in cleaved caspase 3, caspase 8 and Bax induced by BPV. Lipid emulsion attenuated the increases in TUNEL-positive cells induced by BPV. These results suggest that lipid emulsion attenuates a toxic dose of BPV-induced apoptosis via inhibition of the extrinsic and intrinsic apoptotic pathways. The protective effect of lipid emulsion may be partially associated with the relatively high lipid solubility of BPV.

scholarly journals Coupling Activation of Pro-Apoptotic Caspases With Autophagy in the Meckel´s Cartilage

2018 ◽  
pp. 135-140 ◽  
Author(s):  
P. Bíliková ◽  
E. Švandová ◽  
B. Veselá ◽  
J. Doubek ◽  
A. Poliard ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Beclin 1 ◽  
Hypertrophic Chondrocytes ◽  
Caspase 8 ◽  
Major Mechanism ◽  
Histological Sections ◽  
Temporary Structure ◽  
Caspase 2 ◽  
First Time

Mammalian Meckel´s cartilage is a temporary structure associated with mandible development. Notably, its elimination is not executed by apoptosis, and autophagy was suggested as the major mechanism. Simultaneous reports point to pro-apoptotic caspases as novel participants in autophagic pathways in general. The aim of this research was to find out whether activation of pro-apoptotic caspases (-2, -3, -6, -7, -8 and -9) was associated with autophagy of the Meckel´s cartilage chondrocytes. Active caspases were examined in serial histological sections of mouse mandible using immunodetection and were correlated with incidence of autophagy based on Beclin-1 expression. Caspase-2 and caspase-8 were found in Beclin-1 positive regions, whereas caspase-3, -6, -7 and -9 were not present. Caspase-8 was further correlated with Fas/FasL and HIF-1alpha, potential triggers for its activation. Some Fas and FasL positivity was observed in the chondrocytes but caspase-8 activation was found also in FasL deficient cartilage. HIF-1alpha was abundantly present in the hypertrophic chondrocytes. Taken together, caspase-8 activation in the Meckel´s cartilage was demonstrated for the first time. Caspase-8 and caspase-2 were the only pro-apoptotic caspases detected in the Beclin-1 positive segment of the cartilage. Activation of caspase-8 appears FasL/Fas independent but may be switched on by HIF-1alpha.

scholarly journals Vascular nitric oxide and superoxide anion contribute to sex-specific programmed cardiovascular physiology in mice

2009 ◽  
Vol 296 (3) ◽  
pp. R651-R662 ◽  
Author(s):  
Robert D. Roghair ◽  
Jeffrey L. Segar ◽  
Kenneth A. Volk ◽  
Mark W. Chapleau ◽  
Lindsay M. Dallas ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Locomotor Activity ◽  
Nitric Oxide Synthase ◽  
Dietary Intervention ◽  
Female Offspring ◽  
High Salt ◽  
Male Offspring ◽  
Partial Substitution ◽  
Oxide Synthase

Intrauterine environmental pertubations have been linked to the development of adult hypertension. We sought to evaluate the interrelated roles of sex, nitric oxide, and reactive oxygen species (ROS) in programmed cardiovascular disease. Programming was induced in mice by maternal dietary intervention (DI; partial substitution of protein with carbohydrates and fat) or carbenoxolone administration (CX, to increase fetal glucocorticoid exposure). Adult blood pressure and locomotor activity were recorded by radiotelemetry at baseline, after a week of high salt, and after a week of high salt plus nitric oxide synthase inhibition (by l-NAME). In male offspring, DI or CX programmed an elevation in blood pressure that was exacerbated by Nω-nitro-l-arginine methyl ester administration, but not high salt alone. Mesenteric resistance vessels from DI male offspring displayed impaired vasorelaxation to ACh and nitroprusside, which was blocked by catalase and superoxide dismutase. CX-exposed females were normotensive, while DI females had nitric oxide synthase-dependent hypotension and enhanced mesenteric dilation. Despite the disparate cardiovascular phenotypes, both male and female DI offspring displayed increases in locomotor activity and aortic superoxide production. Despite dissimilar blood pressures, DI and CX-exposed females had reductions in cardiac baroreflex sensitivity. In conclusion, both maternal malnutrition and fetal glucocorticoid exposure program increases in arterial pressure in male but not female offspring. While maternal DI increased both superoxide-mediated vasoconstriction and nitric oxide mediated vasodilation, the balance of these factors favored the development of hypertension in males and hypotension in females.

scholarly journals Prostaglandin E1 Attenuates Post-Cardiac Arrest Myocardial Dysfunction via Inhibiting Mitochondria-Mediated Cardiomyocyte Apoptosis

2020 ◽  
Author(s):  
Chenglei Su ◽  
Xinhui Fan ◽  
Feng Xu ◽  
Jiali Wang ◽  
Yuguo Chen
Keyword(s):  
Cardiac Arrest ◽  
Cytochrome C ◽  
Rat Model ◽  
Prostaglandin E1 ◽  
Caspase 3 ◽  
Myocardial Dysfunction ◽  
Cardiomyocyte Apoptosis ◽  
H9c2 Cells ◽  
Protein Levels ◽  
Mptp Opening

Abstract Background: Post-cardiac arrest myocardial dysfunction (PAMD) is a leading cause of death in resuscitated patients after cardiac arrest (CA). Prostaglandin E1 (PGE1) is a clinical drug used to mitigate ischemia injury. However, its effect on PAMD remains unknown. Methods: We investigated the protective effects of PGE1 on PAMD in a rat model of cardiac arrest and a hypoxia-reoxygenation (H/R) H9c2 cell model. Forty-two male Wistar rats were randomly assigned to CA, CA+PGE1, and sham groups. Asphyxia for 8 min followed by cardiopulmonary resuscitation was performed in the CA and CA+PGE1 groups. PGE1 (1 μg/kg) was intravenously administered at the onset of return of spontaneous circulation (ROSC). Ejection fraction (EF) and cardiac output (CO) were measured at baseline, 1, 2, 3, and 4 h after ROSC; survival was monitored for 72 h. Cardiomyocyte apoptosis, mitochondrial permeability transition pore (mPTP) opening, and protein levels of glycogen synthase kinase 3β (GSK3β), cytochrome c, and cleaved caspase-3 were measured 4 h after ROSC. H9c2 cells were treated with PGE1(0.5 μM) at the start of reoxygenation. Apoptosis, mPTP opening, and protein levels of GSK3β, cytochrome c, and cleaved caspase-3 of H9c2 cells were detected. Results: Compared to the CA group, PGE1 treatment significantly increased the EF and CO within 4 h after ROSC and improved the survival rate. It activated GSK3β, prevented mPTP opening, suppressed cytochrome c and cleaved caspase-3 expression, and reduced cardiomyocyte apoptosis in the rat model. In vitro, Changes in GSK3β, mPTP opening, cytochrome c and cleaved caspase-3 expression, and apoptosis in H9c2 cells were consistent with those in the rat model. Conclusions: Our results indicate that PGE1 attenuates PAMD via inhibiting mitochondria-mediated cardiomyocyte apoptosis.

Abstract 446: Deletion of Il-6 Prevents Development of Cardiac Damage and Dysfunction in Chronic Ang Ii-salt-induced Hypertension

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Germán E González ◽  
Nour-Eddine Rhaleb ◽  
Pablo Nakagawa ◽  
Yun-He Liu ◽  
Oscar A Carretero
Keyword(s):  
Blood Pressure ◽  
Cardiac Dysfunction ◽  
High Salt ◽  
Myocardial Inflammation ◽  
Pressure Measurements ◽  
Ang Ii ◽  
Cardiac Damage ◽  
High Salt Diet ◽  
Salt Diet ◽  
Induced Hypertension

IL-6 knockout (KO) mice were reported to spontaneously develop cardiac dysfunction and fibrosis. These KO mice also develop less hypertension when fed high salt and infused with angiotensin II (Ang II). We tested the hypothesis that in IL-6-KO mice the attenuated hypertension in response to Ang II-salt is due to the development of cardiac dysfunction. Male C57Bl/6J and IL-6-/- mice (B6.129S6- Il6 tm1Kopf ) were implanted with telemetry devices for blood pressure measurements, infused with vehicle (V) or Ang II (90 ng/min/mouse subcutaneously) and feed a high salt diet (4% salt diet, HS) for 8 weeks (W). We studied 4 experimental groups: 1) C57BL/6J + V (n=9); 2) IL6-KO + V (n=9); 3) C57BL/6J + Ang II (n=8) and 4) IL6-KO + Ang II (n=6). Blood pressure and echocardiography data were collected before starting the HS diet and Ang II infusion (baseline) and 8 weeks after HS alone or combined with Ang II. Results (Mean±SEM) Conclusion: Our results do not support our hypothesis and shows that the lack of IL-6 does not affect development of hypertension or cardiac hypertrophy but rather prevents cardiac dysfunction, LV dilation, myocardial inflammation and fibrosis in Ang II-salt-induced hypertension, suggesting that IL-6 plays an important role in cardiac dysfunction associated with hypertension.

Evidence that FOXO3a is involved in oocyte apoptosis in the neonatal rat ovaryThis paper is one of a selection of papers published in this special issue entitled “Second International Symposium on Recent Advances in Basic, Clinical, and Social Medicine” and has undergone the Journal's usual peer review process.

2010 ◽  
Vol 88 (4) ◽  
pp. 621-628 ◽  
Author(s):  
Xu-Xia Sui ◽  
Li-Li Luo ◽  
Jin-Jie Xu ◽  
Yu-Cai Fu
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Caspase 3 ◽  
Neonatal Rat ◽  
Immunofluorescent Staining ◽  
Oocyte Nucleus ◽  
Caspase 8 ◽  
Double Labeling ◽  
Cycle Arrest ◽  
Old Rats

Previous studies have proposed that the forkhead transcription factor FOXO3a is involved in cell cycle arrest and apoptosis and that it may also repress follicular development by inducing cell cycle arrest in ovaries. We have recently demonstrated that FOXO3a induces oocyte apoptosis of neonatal rat ovaries under in vitro conditions. In the present study, we evaluated the role of FOXO3a in oocyte apoptosis under in vivo conditions. Ovaries from rats were obtained from newborns on postnatal day (PD) 1, 2, 3, and 4. TUNEL assay results showed that oocyte apoptosis occurred mainly on PD 1 and 2. Immunohistochemical staining of FOXO3a, Bim, Fas ligand (FasL), p27KIP1, caspase-8, and caspase-3 showed that they were all expressed mainly in naked oocytes on PD 1 and 2. The percentage of positive FOXO3a staining of oocytes reached peak levels in the ovaries of 2-day-old rats, which was consistent with the rate of the apoptotic profiles determined by TUNEL. The percentage between TUNEL-positive and FOXO3a-positive oocytes in the nucleus showed no statistical differences within the 4-day-old rat ovaries. Furthermore, the positive oocyte percentage of the target factors of FOXO3a (Bim, p27KIP1, and FasL) and pro-apoptotic proteins (caspase-3 and caspase-8) also reached peak levels in the ovaries of 2-day-old rats, which was similar to the rate of FOXO3a-positive oocytes. These results suggest that FOXO3a in the oocyte nucleus is involved in oocyte apoptosis; that is, FOXO3a-positive oocytes may be the apoptotic cells. To verify this, rat oocytes were subjected to TUNEL and immunofluorescent double-labeling assays. We found that TUNEL-positive cells were also FOXO3a-, Bim-, or FasL-positive. To identify the downstream target of FOXO3a, double immunofluorescent staining with antibodies to Bim and FasL was performed. We found that FOXO3a-positive cells were also Bim- and FasL-positive. We conclude that the overexpression of FOXO3a in the oocyte nucleus of neonatal rat ovaries may play an important role in the apoptosis of naked oocytes, and that Bim, FasL, and p27KIP1 are the key downstream factors of FOXO3a.

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