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Title:	Kesan minyak sawit dan minyak soya yang dipanaskan terhadap faktor-faktor berkaitan aterosklerosis pada tikus yang diovariektomi
Authors:	Siti Khadijah Adam (P34164)
Supervisor:	Prof. Dr. Kamsiah Jaarin
Keywords:	Minyak sawit Minyak soya Tikus yang diovariektomi Dissertations, Academic -- Malaysia
Issue Date:	24-May-2011
Description:	Minyak sayuran yang dipanaskan berulang kali meningkatkan peroksidasi lipid serta menggalakkan pembentukan lesi aterosklerosis. Penurunan aras estrogen setelah menopaus meningkatkan risiko tersebut kerana hormon estrogen mempunyai kesan antioksidan yang menghalang proses peroksidasi lipid. Ini bermakna risiko aterosklerosis meningkat dengan pengambilan minyak sayuran yang mengalami oksidasi termal pada subjek pascamenopaus. Kajian ini bertujuan mengenalpasti kesan pengambilan minyak sawit dan minyak soya yang dipanaskan berulang kali terhadap tikus yang diovariektomi. Tikus betina Sprague-Dawley yang diovariektomi diberi diet kolesterol 2% berserta 15% (berat/berat) minyak sawit atau minyak soya segar serta dipanaskan sekali atau lima kali selama empat bulan. Hasil kajian mendapati pemanasan kedua-dua minyak sawit dan soya sebanyak lima kali menyebabkan penurunan signifikan ke atas kandungan vitamin E minyak serta penurunan aras vitamin E di dalam serum tikus kajian. Pemanasan minyak sawit dan minyak soya meningkatkan nilai peroksida minyak. Nilai tersebut adalah paling tinggi dalam minyak soya yang dipanaskan lima kali. Ovariektomi meningkatkan aras peroksidasi lipid, kolesterol total dan homosistein serum. Peningkatan aras peroksidasi lipid, kolesterol total serta lipoprotein berketumpatan rendah adalah paling tinggi dalam kumpulan yang diberi minyak soya yang dipanaskan lima kali. Kajian histologi aorta di bawah mikroskop cahaya tidak menunjukkan pembentukan lesi aterosklerosis. Sebaliknya, terdapat peningkatan nisbah tunika intima/tunika media bagi kumpulan yang diberi minyak sawit atau minyak soya yang dipanaskan lima kali. Peningkatan tersebut disebabkan oleh penurunan ketebalan tunika media. Kajian mikroskop elektron pada kumpulan tikus yang diovariektomi menunjukkan terdapatnya penebalan tunika intima dengan kehadiran serat kolagen dan vakuol serta apoptosis sel endotelium yang merupakan petanda awal lesi aterosklerosis. Perubahan ultrastruktur ini kurang kelihatan dengan pengambilan minyak sawit atau minyak soya segar. Kesan perlindungan ini berkurangan apabila minyak makanan ini dipanaskan. Kesimpulannya, kajian ini mendapati minyak sawit atau minyak soya segar dapat melindungi daripada aterosklerosis. Sebaliknya pengambilan minyak yang dipanaskan meningkatkan risiko aterosklerosis pada model tikus pascamenopaus. Peningkatan risiko tersebut adalah lebih tinggi dengan pengambilan minyak soya yang dipanaskan lima kali berbanding minyak sawit yang dipanaskan lima kali.,Repeatedly heated vegetable oils cause an increase in lipid peroxidation and promote the development of atherosclerosis. The decrease in the level of estrogen following menopause increases the risk of developing atherosclerosis which is due to the loss of the antioxidant effect of estrogen which prevents the lipid peroxidation process. Hence, the risk of developing atherosclerosis is further increased in postmenopausal subjects with the consumption of thermally oxidized vegetable oil. This study was performed to determine the effects of consumption of repeatedly heated palm oil and soy oil on ovariectomized rats. Ovariectomized female Sprague-Dawley rats were administered 2% cholesterol diet fortified with 15% (weight/weight) fresh, onceheated and five-times-heated palm oil or soy oil for four months. The findings of the study suggested that heating both palm and soy oils for five times caused a significant reduction in the vitamin E content in the oils as well as the level of serum vitamin E in the rats. Heating of palm oil and soy oil caused an increase in the peroxide value in the oils. The values were highest in the five-times-heated soy oil. Ovariectomy caused an increase in serum lipid peroxidation, total cholesterol and homocysteine levels. The increase in lipid peroxidation, total cholesterol and low-density lipoprotein levels was the highest in the group treated with five-times-heated soy oil. Histological study of the aorta under light microscopy did not show the presence of atherosclerotic lesions. Conversely, there was an increase of tunica intima/tunica media ratio in the groups fed five-times-heated palm oil or soy oil. The increase was due to the reduction of tunica media thickness. Electron microscopic study on the ovariectomized rats showed that there was an increase in tunica intima thickness with the presence of collagen fibres and vacuoles along with apoptosis of endothelial cells indicating an early atherosclerotic lesion. The ultrastructural changes were less with the consumption of fresh palm oil or soy oil. The protective effects were reduced once the oils were heated. In conclusion, the consumption of fresh palm oil or soy oil offered protection from atherosclerosis. In contrast, the consumption of these heated vegetable oils increased the risk of atherosclerosis in the postmenopausal rat model. The increase was higher in the five-times-heated soy oil treated group as compared to the fivetimes-heated palm oil treated group.,Ph.D
Pages:	243
Call Number:	QV20.5 .S624k 2011 9
Publisher:	UKM, Kuala Lumpur
Appears in Collections:	Faculty of Medicine / Fakulti Perubatan

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