الفهرس 
Introduction.and.Aim.of.the.WorkOnly 14 pages are availabe for public view
 |  | from | 170 |  |  |
| | | from | 170 | | |
Abstract
This study aimed to address the role of BA in experimentally STZ-induced diabetes in albino Wistar rats through studying the SAPK-JNK pathway.
Sixty male Wistar albino rats weighing 100-120 g were purchased from the National Research Centre (Cairo, Egypt). The rats were kept in a controlled environment and were allowed free accesses to standard chow diet and tap water and housed in polyacrylic cages. Sixty rats were fasted overnight and were given a single STZ dose dissolved in cold citrate buffer (0.1M, pH 4.5) at 50 mg/kg BW, intraperitoneally (i.p), for T2DM induction. Rats with fasting plasma glucose (FPG) level above 200 mg/dl after 72 hours was considered as diabetic along with normal control. In addition to the normal apparently healthy control group (10 rats), the STZ-treated rats were randomly divided into five groups (10 rats each) as follows:
Group1 (control): normal apparently healthy rats were orally given saline by rat oral gavage and injected i.p. with a single dose of citrate buffer (0.1M, pH 4.5).
group 2 (STZ): rats received a single STZ dose i.p (50 mg/kg BW).
group 3 (STZ + Balanites crude extract (BCE)): rats received STZ as mentioned in group 2 and treated orally with BCE 50 mg/kg/day for one month.
group 4 (STZ + Balanites butanol fraction (BBF)): rats received STZ as mentioned in group 2 and treated orally with BBF 50 mg/kg/day for one month.
group 5 (STZ + Balanites dichloromethane fraction (BDF)): rats received STZ as mentioned in group 2 and treated orally with BDF 50 mg/kg/day for one month.
group 6 (STZ + gliclazide (reference drug)): rats received STZ as mentioned in group 2 and treated orally with gliclazide 10 mg/kg/day for one month.
At the end of the experimental period, animals from the normal and the five STZ-induced diabetic groups were food deprived for 12-14 hours in order to withdraw blood from retro-orbital plexus for biochemical analysis, and then rats were killed by cervical dislocation.
Blood was collected in fluoride tubes where they were centrifuged at 3000 rpm for 15 minutes to obtain plasma for FPG estimation. Another blood part was collected in EDTA tubes and was divided into two aliquots. The first aliquot was used for HbA1c estimation. The second aliquot was centrifuged at 3000 rpm for 15 minutes in order to obtain plasma which in turn was divided into 2 parts. The first part was used for complete lipid profile estimation while the other part was stored at -80°C until insulin and LA assay using ELISA kits. After sacrificing of rats, their livers, skeletal muscles and pancreases were dissected out, washed with cold phosphate buffer saline (PBS) and blotted dry with filter paper. Liver (1 g) was homogenized in 5 ml PBS using tissue homogenizer (Yellow line DI 18 Basic, Deutschland, Germany). The liver homogenates were centrifuged at 4000 rpm for 15 minutes. The supernatants were collected and used directly for estimation of malondialdehyde (MDA), reduced glutathione (GSH) levels, catalase, and superoxide dismutase (SOD) activities. The pancreases were preserved at -80˚C for ASK1, JNK1, p53 and IRS1 estimation. The skeletal muscles were preserved at -80˚C until the GLUT4 determination. The study was approved by our institutional animal ethics committee of Beni-Suef University and all procedures for agent administration, blood, and tissue collection were in accordance with the 8th edition of the Guide for the Care and Use of Laboratory Animals published in 2011 by the United States National Academy of Sciences.
STZ significantly increased FPG and HbA1c levels compared with the normal group. All treated groups showed significantly lowered FPG compared with STZ group. The lowest FPG level was in BBF and BCE groups even lower than that of the gliclazide group. Moreover, BA fractions significantly reduced HbA1c level compared with STZ and gliclazide groups.
STZ significantly decreased insulin level compared with normal and BA fractions-treated groups. BBF significantly increased insulin level compared with STZ, BCE, BDF and gliclazide groups. The order of increasing insulin level was BBF ˃ BCE ˃ gliclazide ˃ BDF ˃ STZ. Additionally, STZ significantly elevated LA level compared with the normal group. Treatment with BA fractions significantly decreased LA level compared with STZ group. Surprisingly, BBF normalized LA level, which did not occur in other groups.
Treatment with BA fractions or gliclazide significantly decreased TC level compared with STZ group. Moreover, BA fractions and gliclazide succeeded in decreasing higher TG level especially in BCE and BBF groups, which were comparable to normal levels while in BDF and gliclazide groups levels were still higher than the normal group. On the other hand, BA fractions significantly increased HDL-C compared with STZ group. Gliclazide showed the least increase in HDL-C compared with BA fractions. BA fractions significantly decreased LDL-C and this effect appeared in the BBF and BCE groups. On contrary, gliclazide failed to decrease higher LDL-C level.
STZ significantly elevated MDA level compared with normal control. Treatment with BA fractions or gliclazide significantly decreased MDA level compared with STZ group and the lowest MDA levels were present in the three BA fractions-treated groups. STZ significantly reduced GSH level compared with the normal group. BA fractions significantly increased GSH level compared with STZ group. Although BDF treatment showed the least increase in GSH level compared to the other two fractions, the three BA fractions were still superior in raising GSH level to gliclazide. Liver catalase and SOD activities. STZ significantly decreased catalase and SOD activities compared to the normal control. The catalase activity in the BBF group was comparable to that of the normal group and higher than that in BDF. Moreover, catalase activity was significantly higher in the three BA extracts compared to the gliclazide group. Additionally, BBF significantly increased SOD activity compared to the normal control, the other two extracts or gliclazide groups. The least increment in SOD activity was found in the BDF group. Gliclazide normalized the SOD activity placing it significantly lower than that of the BBF or BCE treated groups and higher than that of the BDF treated group.
STZ significantly elevated ASK1, JNK1, and p53 levels compared with normal control. BA fractions significantly reduced the elevation in ASK1, JNK1, and p53 levels induced by STZ. STZ significantly reduced IRS1 level compared with the normal group. BA fractions significantly elevated the decreased IRS1 level induced by STZ. Moreover, the IRS1 level was significantly higher in the BCE group compared with gliclazide group. STZ significantly reduced GLUT4 level compared with the normal group. BCE, BBF or gliclazide significantly elevated GLUT4 level compared with STZ group and the highest increase was present in the BCE group. BDF treatment failed to increase GLUT4 compared with STZ group.
The results of this study suggest that BA fractions showed hypoglycemic effect, hypolipidemic effect, insulinotropic effect. BA fractions inhibited oxidative stress which led to inhibition of SAPK-JNK pathway and possibly leads to decrease apoptosis in β-cells.