الفهرس 
Diabetes MellitusOnly 14 pages are availabe for public view
Abstract
T
he present study was performed to reveal the beneficial effects of swimming exercise on type 2 diabetic rat model and explore its mechanisms of action. Also, this study aimed to demonstrate the possible role of the exercise hormone irisin in mitigating the atherosclerotic risk compared to exercise, and to elucidate the possible use of irisin injection in alleviating some of the complication of T2DM.
The present study was carried out on 86 adult male Wistar rats, randomly allocated into the following four experimental groups:
Control group (n=20): Rats in this group were fed control diet for 3 weeks, and then were subjected to a single intraperitoneal (i.p.) injection of citrate buffer (1mL/kg), equivalent to that given with SZT. Rats continued feeding the control diet for another 5 weeks, and then rats were studied.
Type 2 diabetes mellitus (T2DM) group (n=23): Rats in this group were subjected to induction of type 2 diabetes by receiving high fat diet (HFD) for 3 weeks, then were subjected to i.p. injection of STZ in a dose of 30 mg/kg. The high fat diet feeding was continued for further 5 weeks, and then rats were studied.
Type 2 diabetes mellitus, Swim Exercise (T2DM-Ex) group (n=23): Rats in this group were subjected to induction of type 2 diabetes as in T2DM group, one week after STZ injection, diabetic rats were subjected to moderate intensity swim exercise for 30 min, 5 days/week for 4 weeks, and then the rats were studied.
Type 2 diabetes mellitus, Irisin Supplemented (T2DM-Irisin) group (n=20): Rats in this group were subjected to induction of type 2 diabetes as in T2DM group, one week after STZ injection, diabetic rats were subjected to i.p. injection of irisin solution in a dose of 150 µL/rat of prepared irisin (100 ng/mL, dissolved in sterile water), 6 days/week for 4 weeks, and then rats were studied.
All rats were subjected to determination of the following (initially and at the end of the experiment): BW, BMI, and ABP, and to estimation of the following at the end of the experiment: PF weight and PFI, levels of serum nitrite, FBG, plasma insulin, HOMA-IR, serum lipid profile, AI, serum MDA, serum TAC, and plasma TNF-α, as well as, histopathological studies of inguinal adipose tissue, aorta and liver.
The results of the present study revealed that rats with T2DM exhibited a significant decrease in the final BW, final BMI, and their % change, also, increased PF weight and PFI, together with a significant rise in their final SBP, DBP, MBP and their % changes, as well as a significant decrease in the levels of the serum nitrite. Also, a significant rise of FBG, plasma insulin levels and increased HOMA-IR, in addition to, a significant rise of serum levels of TG, TC, LDL-C, AI, and significant reduction in serum HDL-C. Furthermore, a significant rise of serum levels of MDA, decreased serum levels of TAC and increased level of plasma TNF-α when compared to control rats.
In T2DM group, the histopathological studies of the inguinal adipose tissue showed white adipocytes, comparable to that in the control group, but there were large amount of collagen fibers and inflammatory cells in between the adipocytes. In the aorta there was accumulation of foam cells in the subintimal regions and discontinuity of elastic laminae, while in the liver, there was inflammatory infilteration, hepatocytes ballooning with diffuse microvesicular steatosis in the hepatocytes of most lobules.
Treating the T2DM rats with moderate intensity swimming exercise resulted in significant increase in BW, decrease in PF and PFI, also, significant decrease in the SBP, DBP, MBP, and increase serum nitrite level, together with significant decrease in FBG, plasma insulin and HOMA-IR, in addition to, significant decrease in serum TG, TC, LDL-C, AI and increase in HDL-C levels, along with a significant decrease in MDA, and decrease in TNF-α, compared to sedentary diabetic rats.
The histopathological studies of the inguinal adipose tissue, in the exercise group, showed that many brown-like adipocytes (Beige cells) appeared between the white adipocytes. In the aorta, there was accumulation of few foam cells in the subintimal region, while in the liver, most hepatocytes were morphologically comparable to the control, but some hepatocytes show single large fat vacuoles in their cytoplasm (macrovesicular steatosis).
Moreover, treating the T2DM rats with irisin injection caused significant decrease in PF and PFI, as well as, a significant decrease in SBP, DBP, MBP and increase in serum nitrite levels, along with significant decrease in FBG, insulin levels and HOMA-IR, also, significant decrease in serum TG, TC, LDL-C and AI, in addition to a significant decrease in MDA, increase in TAC and decrease in TNF-α, compared to untreated diabetic rats.
In addition, the histopathological changes in the inguinal adipose tissue showed almost complete browning of white adipocytes. In the aorta, the microscopic morphology was comparable to the control, and in the liver, there was macrovesicular steatosis but less evident than exercise group. Histopathological scoring for lobular inflammation, Mallory bodies and hepatocyte ballooning, indicated that irisin group was the least affected one.
These results help to clarify the protective role of irisin against metabolic derangement in diabetes mellitus, suggesting irisin as a new target that could prevent and treat diabetic complications.