الفهرس 
Diabetes MellitusOnly 14 pages are availabe for public view
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Abstract
The prevalence of diabetes mellitus (DM) appears to increase rapidly during recent years in the world. Diabetic cardiomyopathy (DCM) is one major complication in diabetics, which impairs myocardial performance even without coronary artery disease or hypertension (Ding et al., 2018).
Mitochondria are highly dynamic organelles undergoing cycles of fusion and fission to modulate their morphology, distribution, and function. These are referred as ’mitochondrial dynamics’. Myocardial contractile dysfunction is associated with an increase in mitochondrial fission among diabetic patients (Montaigne et al., 2014). Dynamin-related protein 1 (Drp1) is known as the major pro-fission protein whose activity is tightly regulated to clear the damaged mitochondria via mitophagy, ensuring a strict control over the intricate process of cellular and organ dynamics in heart. It has been linked to the pathogenesis of cardiovascular diseases (CVDs) including endothelial dysfunction, smooth muscle remodeling, cardiac hypertrophy, pulmonary arterial hypertension, myocardial ischemia–reperfusion, and myocardial infarction (Jin et al., 2021).
The different mechanisms underlying the potential therapeutic action of apigenin, including cell cycle arrest, apoptosis, anti-inflammatory, and antioxidant function were previously investigated (Seo et al., 2012; Telange et al., 2017). In addition, the anti-diabetic properties of apigenin have been explored by Shay et al. (2015) and Pamunuwa et al. (2016). It was shown to act through various mechanisms, including its capacity to inhibit α-glucosidase activity, increase secretion of insulin, interact with and neutralize reactive oxygen species (ROS) in the cell, which together contribute to the prevention of diabetic complications. Apigenin has also shown the ability to supply moderate nitric oxide (NO) to endothelial cells, thereby limiting the risk of endothelial cell injury and dysfunction from hyperglycemia (Wang et al., 2014).
The current study was carried out at Medical Biochemistry and Molecular Biology Department, Faculty of Medicine, Ain Shams University (2021-2023) in collaboration with Physiology Department, Faculty of Medicine, Ain Shams University. The study was approved by Research Ethics Committee (REC), Faculty of Medicine, Ain Shams University. This study aimed to evaluate and correlate the changes in expression of Drp1 in diabetic rats with cardiovascular complications and to study the effect of apigenin on its expression.
This study was performed on 28 adult male albino rats that were equally divided into four groups; group 1 (control): injected once with 0.05 M citrate buffer, intra-peritoneal (i.p.). group 2 (type 1 diabetic model): injected i.p. once with 40 mg/kg body weight streptozotocin (STZ) dissolved in 0.05 M citrate buffer. group 3 (early apigenin-injected diabetic group) received apigenin (0.78 mg/kg/day dissolved in saline, subcutaneously for 10 days) once confirmed diabetic. group 4 (late apigenin-injected diabetic group) received the same dose of apigenin after 4 weeks of DM confirmation, when the rats became hypertensive as a sign suggesting the development of cardiovascular complications.
All groups were subjected to:
1- Measurement of random blood glucose level in rat tail blood 7 days after induction of diabetes to confirm being diabetic.
2- Measurement of arterial blood pressure and recording of ECG.
3- Scarification of rats followed by blood and tissue sampling, and histological examination.
4- Assessment of serum biochemical parameters (fasting blood glucose, lipid profile, CK-MB and cardiac troponin).
5- Detection of drp1 in cardiac tissue by real time qPCR.
6- Histological examination of H&E stained sections from cardiac tissues.
The results of this study showed the following:
The control group rats’ whole-body weight was significantly higher as compared to diabetic, late and early apigenin-injected diabetic groups. Meanwhile, the heart weight showed no significant difference in groups.
Diabetic and late apigenin-injected groups had significantly higher systolic and diastolic blood pressure values than control and early apigenin-injected groups after 1 month of diabetes. After apigenin injection the systolic and diastolic blood pressures were non-significantly decreased in each of the early and late injected groups.
Regarding heart rate, diabetic rats had higher final heart rate than all studied groups, meanwhile they had lower final QRS voltage than all other groups indicating diabetic cardiomyopathy. Both apigenin-injected groups had higher QRS voltage indicating possible improvement of cardiomyopathy. Considering final Q-Tc, the diabetic group had longer value than the control group with improvement in the early apigenin-injected diabetic group but not the late apigenin-injected diabetic group.
Both apigenin-injected groups showed lower fasting blood glucose (FBG) levels as compared to diabetic rats. The blood glucose lowering effect of apigenin was significantly evident in apigenin-injected groups as compared to diabetic group. Early apigenin-injected group showed much more reduction in serum levels of glucose as compared to diabetic and even late apigenin-injected group.
The diabetic group had significantly higher serum levels of troponin, CK-MB, triacylglycerol (TAG), total cholesterol, and LDL-cholesterol, when compared with the three other groups. Meanwhile, HDL-cholesterol levels were significantly lower in diabetic group as compared to the three other groups.
Apigenin was found to improve the lipid profile by decreasing total cholesterol, TAG and LDL cholesterol, and increasing HDL cholesterol in apigenin-injected diabetic rats (both groups) in comparison to diabetic group. In addition, apigenin-injection caused reduction in cardiac injury markers with more evident troponin reduction in early when compared with late apigenin-injection.
The RQ of Drp1 expression in cardiac tissues from diabetic rats was significantly higher than control, early and late apigenin-injected rats. Although there was no significant difference between early apigenin and late apigenin-injected diabetic groups, apigenin-injection caused decrease in Drp1 expression in comparison to the diabetic rats. Consequently, the timing of apigenin-injection was not significantly reflected on the level of Drp1 expression. To the best of our knowledge, no previous studies have investigated the effect of apigenin on Drp1 in DM. Moreover, there was a significant positive correlation between Drp1 RQ values and elevation of blood pressure, serum FBG and cardiac damage markers. Furthermore, there was a significant positive correlation between RQ of Drp1 and all lipid profile markers except HDL.
The histopathological structural damage of myocardial tissue was evaluated using H&E staining in the different groups of rats. The results revealed that apigenin-injection almost restored the normal structure with disappearance of the signs of inflammation detected in diabetic rats.