الفهرس 
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Abstract
Diabetes mellitus is a metabolic disorder caused by a deficiency in insulin secretion or effectiveness causing chronic hyperglycemia and alterations in microcirculation. This study evaluated the effects of BM-MSCs and/or chrysin on hyperglycemia, hyperlipidemia, and antioxidant levels in NA/STZ-induced diabetic rats and to designate the probable physiological, biochemical and molecular mechanisms of action of these tested agents.
Diabetes was induced in overnight fasted rats by a single intraperitoneal (i.p.) injection of 60 mg STZ/kg b.wt (dissolved in citrate buffer, pH 4.5), 15 minutes after the i.p. administration of 120 mg NA/kg b.wt.
The diabetic rats were divided into four groups; the 1st group was given a similar amount of the vehicle (1% CMC), in which chrysin was dissolved on alternate days until the study’s completion (four weeks). Also, every week for a period of four weeks, this group received an equivalent dosage of DMEM (0.2 mL/rat) intravenously. The 2nd group was treated with chrysin orally at dose levels of 100 mg/kg b.wt/day every other day until the end of the study. The 3rd group was treated BM-MSCs (1 × 106 cells/rat) in 0.2 mL of DMEM into a lateral tail vein every week for four weeks. The 4th group was treated BM-MSCs every week in the same way as 3rd group plus chrysin every other day in the same way as group 2nd for four weeks. Another group of normal animals was preserved under the same laboratory conditions and considered a normal control for diabetic groups. This group was also given the same volume of vehicle (1% CMC) and DMEM (0.2 mL/rat) in the same way as 2nd group for 4 weeks.
After 4 weeks of treatment, animals were fasted overnight to perform oral glucose tolerance test and calculate AUC, and then rats were sacrified and blood samples were collected and centrifuged. The obtained sera were used for quantitative determination of insulin, C-peptide, fructosamine, TNF-α, IL-1β, and IL-13, FFA levels, lipid profile, kidney functions, and liver functions. Livers and kidneys were removed directly after sacrifice, perfused with ice-cold saline, and then homogenized. The homogenate was centrifuged, and the supernatant was used for estimating hepatic glycogen content, glucose-6-phosphatase, and glycogen phosphorylase, as well as Glutathione-S-transferase, glutathione peroxidase, glutathione, superoxide dismutase, and lipid peroxidation in both the liver and kidney. Moreover, pieces of visceral adipose tissues were kept at 80 °C until resistin, adiponectin, IR-Bs, IRS-1, and IRS-2 expression were assessed. The pancreas was extracted and preserved in 10% neutral buffer formalin for histological and immunohistochemical examinations.
The acquired data from the previously stated investigations revealed the following special effects:
• Oral glucose tolerance was impaired in diabetic rats and significantly enhanced in the treated rats.
• The dropped serum insulin and C-peptide levels in diabetic rats were significantly increased as a result of treatments.
• Liver glycogen content was extremely reduced in the diabetic rats and improved in the treated groups.
• The activities of glycogen phosphorylase and glucose-6-phosphatase were significantly decreased in the treated diabetic rats, which reflects the role of treatment in improving the altered activities of these enzymes.
• The AST and ALT activities were significantly raised in NA/STZ-induced diabetic rats as compared to normal ones and declined through treatment, reflecting enhancement in liver function.
• Serum creatinine and urea as markers of kidney function were deleteriously affected in diabetic rats and significantly ameliorated in treated ones.
• Total cholesterol, triglycerides, LDL-cholesterol, vLDL-cholesterol, and free fatty acid concentrations were all significantly higher in the blood of NA/STZ-diabetic rats, but HDL cholesterol was significantly lower. The treatment of diabetic rats with chrysin, BM-MSCs, and their combination led to ameliorative effects on the disrupted lipid profile.
• TNF-α and IL-1β as pro-inflammatory cytokines were massively augmented in the diabetic rats and significantly decreased as a result of treatment with chrysin and BM-MSCs alone or in combination.
• IL-13 as an anti-inflammatory cytokine was significantly increased in the treated diabetic rats, which reflects the role of treatment in improving its decreased levels.
• Visceral dipose tissue adiponectin, IR-Bs, IRS-1, and IRS-2 protein expression have similar behavioural patterns as they were obviously dropped in NA/STZ-induced diabetic rats. The treatment with chrysin and BM-MSCs alone or in combination could potentially upregulate the diminished expression of adiponectin, IR-Bs, IRS-1, and IRS-2 proteins.
• The treatments of diabetic rats with chrysin and BM-MSCs alone or in combination encouraged a remarkable enhancement in the islets’ histological architecture.
• The increased integrated density and area fraction showed that the treatment with chrysin, BM-MSCs, and their combination caused significant immunoreactivity to anti-insulin antibodies.
• Regarding liver and kidney oxidative stress and antioxidant defense enzymes, the exhausted glutathione content as well as the declined glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase activities of NA/STZ-administered rats were potentially alleviated as a result of chrysin and/or BM-MSCs treatments. On the other hand, lipid peroxidation was elevated in diabetic rats and significantly improved in the treated ones.
In conclusion, the possible effects of chrysin and BM-MSCs on NA/STZ-administered rats may be elucidated on the basis of lowering inflammation, restoring β-cell functionality, and attenuating insulin resistance and oxidant-antioxidant system controlling. Moreover, the treatment with BM-MSCs combined chrysin produced the most potent effect on NA/STZ-induced diabetic rats. To evaluate the effectiveness and safety of these agents in humans, more clinical research is needed.