Effects of stingless bee propolis on oxidative stress and structural integrity of heart in streptozotocin-induced diabetic rats
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Date
2020-04
Authors
Zhi, Lim Oon
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Abstract
Diabetes mellitus is a concerning non-communicable disease worldwide that
has great socio-economic impact especially in Malaysia where the prevalence beats
global figure. Type 1 diabetes mellitus is a chronic metabolic disorder characterised
by persistent hyperglycaemia leading to overproduction of oxidative stress that
causes diabetic cardiomyopathy. Stingless bee propolis is rich in phenolic
compounds that is made of resins from plant exudates and stingless bee’s saliva. It
has antihyperglycaemia, antioxidative and antiischemic potential. Nevertheless, no
previous study reported the effect of stingless bee propolis on diabetic heart. Thus,
this study aims to determine the effect of supplementation of stingless bee propolis
on oxidative stress and histopathology of heart in streptozotocin-induced diabetic
rats. The polar antioxidative compounds was extracted from raw stingless bee
propolis using ethanolic extract. Adult male Sprague Dawley rats was divided into
five groups (n=8): normoglycaemia (non-DM), untreated diabetes mellitus (DM),
diabetic treated with 300 mg/kg/day metformin (DM+Metformin), diabetic treated
with 300 mg/kg/day propolis (DM+Propolis), diabetic treated with both 300
mg/kg/day metformin and 300 mg/kg/day propolis (DM+Combined) and treatment
was given on daily basis. Single dose of 60mg/kg streptozotocin was administered
intraperitoneally to induce type 1 diabetes mellitus. Treatment was given for four
weeks duration following successful induction of diabetes mellitus via oral gavage.
Body weight, fasting blood glucose, water intake and food intake were taken every
week. The rats were sacrificed after four weeks using 300 mg/kg of sodium
pentobarbital. Serum and heart were collected for determination of colourimetric
assays (oxidative stress markers and antioxidative enzymes) and histopathology.
Diabetic rats experienced manifestation of hyperglycaemia such as polydipsia,
polyphagia and weight loss. Their heart contains higher oxidative stress markers and
alteration in antioxidative enzymes. Heart of diabetes mellitus rats showed features
of diabetic cardiomyopathy including cardiomyocyte hypertrophy, cardiac fibrosis
and perivascular fibrosis. Metformin or propolis supplementation reversed the
clinical manifestation of diabetic mellitus but propolis alleviated histopathology and
biochemical alteration of diabetic cardiomyopathy better than metformin. However,
combination of metformin and propolis supplementation observed better
improvement than metformin alone. In a nutshell, this study of stingless bee propolis
managed to produce positive data on diabetic cardiomyopathy in rats through its
antihyperglycaemic and antioxidative properties.
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Keywords
Diabetes mellitus