الفهرس 
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Abstract
The goal of the present work was to investigate the anti-diabetic and
anti-lipidemic properties of momordica charantia fruit extract in
experimentally induced diabetes and to study the possible
physiological mechanisms of action of this tested plant.
Adult male albino rats (120-160 g) were allocated for the present
study. After acclimatization period of two weeks, each animal was
injected intra-peritoneally with a single dose of 100 mg/kg B.Wt.
alloxan monohydrate dissolved in citrate buffer (pH 4.5). Ten days
after alloxan injection, rats were screened for measuring blood glucose
level. The mild diabetic rats (rats having serum glucose level ranging
from 180-300 mg/dl) were divided into three groups, the first group
was given distilled water and considered as diabetic control. The
second group received rosiglitazone (Avandia), an oral hypoglycemic
drug, to compare its effect with bitter melon. Other 2 groups of normal
animals were kept under the same laboratory conditions, one regarded
as a normal control for the diabetic groups and the other received the
plant extract to test its effect in normal condition. All treatments were
applied orally by gastric intubation daily for 4 weeks.
At the end of the experimental period, oral glucose tolerance test
was performed before sacrifice. After sacrifice blood was collected for
the determination of Serum insulin, blood glycohemoglobin (HbA1c)
%, ALT, AST and lipid profiles (triglycerides, total cholesterol, LDLcholesterol
and HDL-cholesterol). Livers and pancreata were quickly
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removed after dissection for measuring glycogen content and studying
the histopathological changes respectively.
To suggest the possible mechanisms of hypoglycemic action of
bitter melon, its effects on peripheral glucose uptake by rat diaphragm
and insulin release from isolated islets of Langerhans were studied in
vitro, in addition to its effect on Intestinal glucose absorption in situ.
These were compared to control studies.
An increase in Serum glucose, ALT, AST, triglycerides, Total
cholesterol, LDL-cholesterol and Blood glycohemoglobin, while a
decrease in Body weight, Serum insulin, liver glycogen and serum
HDL-cholesterol were observed in alloxan diabetic control rats as
compared to the normal control group. Treatment of diabetic rats with
either bitter melon or rosiglitazone produced opposite results denoting
ameliorative effect on carbohydrate and lipid metabolism.
Concerning the in vitro and insitu experiments, bitter melon found
to increase peripheral glucose uptake by rat diaphragm, have
insulinotropic effect and decrease intestinal glucose absorption, while
rosiglitazone increased only glucose uptake by rat diaghragm.
With regard to the histopathological changes, microscopic
examination of the pancreas showed destructed β cells and vacuolated
cytoplasm in diabetic control rats after 4 weeks experimental period.
On the other hand, treatment of diabetic rats with either bitter melon
or rosiglitazone increased β cell numbers in the pancreas.
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Results obtained from diabetic rats treated with bitter melon were
significant as compared to diabetic control and rosiglitazone.
In conclusion, the present study revealed that bitter melon has both
pancreatic (insulinotropic) and extrapancreatic (insulin mimetic)
mechanisms of anti-diabetic effect so, it may act as a good alternative
in treatment of diabetes mellitus.