Adewole Stephen O, Caxton-Martins Ezekiel A, Ojewole John A O
Department of Anatomy and Cell Biology, Faculty of Basic Medical Sciences, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
Afr J Tradit Complement Altern Med. 2006 Aug 28;4(1):64-74. doi: 10.4314/ajtcam.v4i1.31196.
This study was undertaken to investigate the protective effects of quercetin (QCT) on the morphology of pancreatic beta-cells against diabetes mellitus and oxidative stress experimentally-induced by streptozotocin (STZ) treatment in Wistar rats. Fifty male and female Wistar rats (200-250 g) were randomly divided into three experimental groups (i. e., control, STZ-treated, and STZ + Quercetin-treated groups). Diabetes was induced in the diabetic groups (B and C) of animals, by a single intraperitoneal injection of STZ (75 mg/kg), while each of the rats in the 'control' group received equal volume of citrate buffer (pH 6.3) solution intraperitoneally. In group C rats, quercetin (QCT, 25 mg/kg/day i.p.) was injected daily for 3 days prior to STZ treatment, and QCT administration continued until the end of the study period (30 days). Diabetes mellitus was confirmed by using Bayer's Glucometer Elite and compatible blood glucose test strips. The rats were sacrificed serially until the end of the study period (after 30 days). The pancreases of the sacrificed rats were excised and randomly processed for histological staining and biochemical assays for antioxidant enzymes [such as glutathione peroxidase (GSHPx), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and serum nitric oxide (NO)]. In the diabetic state, pancreatic beta-cells of STZ-treated group B rats histologically demonstrated an early chromatin aggregation, cytoplasmic vesiculation in the central beta-cells, nuclear shrinkage, and lysis of beta-cells with distortion of granules. The morphology of QCT-treated rats' pancreases showed viable cellularity with distinct beta-cell mass. STZ treatment significantly decreased (p<0.05) GSHPx, SOD, CAT and pancreatic insulin content. However, STZ treatment increased blood glucose concentrations, MDA and serum NO. The QCT-treated group of animals showed a significant decrease (p<0.05) in elevated blood glucose, MDA and NO. Furthermore, QCT treatment significantly increased (p<0.05) antioxidant enzymes' activities, as well as pancreatic insulin contents. Quercetin (QCT) treatment protected and preserved pancreatic beta-cell architecture and integrity. In conclusion, the findings of the present experimental animal study indicate that QCT treatment has beneficial effects on pancreatic tissues subjected to STZ-induced oxidative stress by directly quenching lipid peroxides and indirectly enhancing production of endogenous antioxidants.
本研究旨在通过链脲佐菌素（STZ）诱导Wistar大鼠患糖尿病和氧化应激，来研究槲皮素（QCT）对胰腺β细胞形态的保护作用。将50只体重200 - 250克的雄性和雌性Wistar大鼠随机分为三个实验组（即对照组、STZ处理组和STZ + 槲皮素处理组）。通过腹腔注射单次给予STZ（75毫克/千克）诱导糖尿病组（B组和C组）动物患糖尿病，而“对照组”的每只大鼠腹腔注射等量的柠檬酸盐缓冲液（pH 6.3）溶液。在C组大鼠中，在STZ处理前3天每天腹腔注射槲皮素（QCT，25毫克/千克/天），并且QCT给药持续到研究期结束（30天）。使用拜耳血糖仪精英版和配套的血糖测试条确认糖尿病。在研究期结束前（30天后）依次处死大鼠。切除处死大鼠的胰腺，随机进行组织学染色和抗氧化酶[如谷胱甘肽过氧化物酶（GSHPx）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、丙二醛（MDA）和血清一氧化氮（NO）]的生化分析。在糖尿病状态下，STZ处理组B大鼠的胰腺β细胞在组织学上表现为早期染色质聚集、中央β细胞的细胞质空泡化、核收缩以及β细胞溶解伴颗粒变形。槲皮素处理大鼠的胰腺形态显示细胞活力良好，β细胞团明显。STZ处理显著降低（p<0.05）GSHPx、SOD、CAT和胰腺胰岛素含量。然而，STZ处理增加了血糖浓度、MDA和血清NO。槲皮素处理组动物的血糖、MDA和NO升高水平显著降低（p<0.05）。此外，槲皮素处理显著增加（p<0.05）抗氧化酶活性以及胰腺胰岛素含量。槲皮素（QCT）处理保护并维持了胰腺β细胞的结构和完整性。总之，本实验动物研究结果表明，QCT处理通过直接淬灭脂质过氧化物和间接增强内源性抗氧化剂的产生，对遭受STZ诱导的氧化应激的胰腺组织具有有益作用。
