11Beta-hydroxysteroid dehydrogenase bioactivity is increased in the colon but not kidneys of rats given supplementary thyroxine.

The aim of this study was to investigate the effect of altered thyroid status on 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD type 1) and type 2 (11beta-HSD type 2) bioactivity in rat kidney and colon. Male Sprague-Dawley rats (250 g) were treated with either L-thyroxine (T4) or propylthiouracil (PTU) for 4 weeks. Blood were then analysed for serum thyroxine, sodium (Na+) and potassium (K+). The kidneys and colon were assayed for 11beta-HSD type 1 and 11beta-HSD type 2 bioactivity. In T4 treated rats the serum thyroxine was significantly elevated (p<0.05) whilst PTU decreased serum thyroxine significantly (p<0.001) compared to controls. Serum Na+ and K+ were within normal limits. There were no significant changes in 11beta-HSD type 1 bioactivity in both treatment groups compared to controls. However, the 11beta-HSD type 2 bioactivity in rats given thyroxine was significantly higher in the colon (p<0.003) compared to controls. We conclude that altered thyroid status had no effect on 11beta-HSD type 1 bioactivity but 11beta-HSD type 2 bioactivity was elevated in the colon of rats given supplementary thyroxine.

The effect of ∞-lipoic Acid in blood lipid levels and malondialdehyde in atherosclerotic-induced new zealand white rabbit.

∞-Lipoic acid (ALA) is a naturally occuring cofactor that serves as an acyl carrier in oxidative decarboxylation of α-keto acids in carbohydrate metabolism. Current findings suggest that ∞-lipoic acid and its reduced form, dihydrolipoic acid (DHLA) may act as antioxidants and are able to quench free radicals in vitro and in vivo. However, the mechanism underlying the process is still unknown. In this study, atherosclerotic lesions were induced in six groups of adult male NZW rabbits labelled as group K, A, B, C, D, E (n=6) by giving 100g/head/day of 2% cholesterol-rich diet for ten weeks. While group K acted as a control, the rest were supplemented with ALA orally (1.4, 2.8, 4.2, 8.0 and 10mg/kg, respectively). In week ten, venous blood samples drawn from ear lobes were analysed for complete lipid profile and peroxidation index. The results showed a significant reduction of total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C) levels in most of the treated groups as compared to the control whereas apo-A levels showed a significant increase in group C and D. However, microsomal lipid peroxidation index, malondialdehyde (MDA) was found to be not significantly different. These findings suggest that ∞-lipoic acid may act as a lipid lowering agent in dose dependent manner in premature stage of atherosclerosis but was unable to inhibit lipid peroxidation processes in matured stage of atherosclerosis in rabbits fed a high cholesterol diet.

Role of vitamin e on oxidative stress in smokers.

Cigarette smoke contains numerous oxygen free radicals that when inhaled, overwhelm antioxidant defenses and produce a condition of oxidative stress. This study investigated whether or not supplementation with vitamin E can affect the state of oxidative stress in healthy smokers. In this randomised double blind trial, 32 smokers received 200 mg of vitamin E or placebo daily for 8 weeks. All smokers in the vitamin E group completed the trial whilst only nine in the placebo group completed the trial. Plasma vitamin E concentrations increased significantly [P<0.02] in the vitamin E group. The release of malondialdehyde [MDA] from erythrocytes was not significantly different between the two groups at baseline and was clearly reduced [P<0.01] after 8 weeks of vitamin E supplementation. Vitamin E increased erythrocyte superoxide dismutase activity [P<0.02] and decreased gluthathione peroxidase activity [P<0.02]. No changes were detected in plasma MDA. We conclude that daily supplementation with 200 mg of vitamin E for 8 weeks improved the oxidative stress state in smokers.

Use Piper sarmentosum as an effective antidiabetic supplement in South East Asia: a review.

Herbs with antidiabetic activity have a potential role to play. Herbal medicines have been widely used in South East Asia because of lesser side effects and cost effectiveness. The main aim of this review article was to disseminate important information regarding the use of herbal products in oxidative stress involved in diseases like diabetes mellitus. The article highlights some of the traditional medicinal plants which have been widely used in South East Asia with special emphasis on Piper sarmentosum. Piper sarmentosum have been reported to possess varying degree of hypoglycemic, antidiabetic and other additional properties. The antioxidant properties of the herbs may be effective in controlling the oxidative damage produced during diabetes mellitus. The review article highlights the positive role of traditional herbs towards diabetes mellitus and also describes its complications.

Effects of Garcinia atroviridis on serum profiles and atherosclerotic lesions in the aorta of guinea pigs fed a high cholesterol diet.

INTRODUCTION: The fruit extract of Garcinia atroviridis (G. atroviridis) contains hydroxycitric acid and flavonoids, which have been reported to have a hypolipidaemic property. This extract with solvent methanol was used to investigate its effects on serum lipid profiles of guinea pigs fed a high cholesterol diet. METHODS: 24 male Dunkin Hartley guinea pigs were randomly divided into four groups. The first group served as controls and was fed with commercial rabbit chow. The second group was given only G. atroviridis by oral gavage (50 mg/body weight). The third group was fed a one percent cholesterol diet in food pellets in order to induce atherosclerosis. The fourth group was administered G. atroviridis with cholesterol. All the treatments were given daily for eight weeks, after which the animals were sacrificed, and the blood and aorta were taken for biochemical analysis and histological studies. RESULTS: The supplementation of G. atroviridis with a cholesterol diet decreased the level of lipid profile in the serum. Histological studies showed a reduction in fat deposition in the aorta of high cholesterol diet animals given G. atroviridis as compared to the high cholesterol diet group. CONCLUSION: This study has shown that dietary intake of G. atroviridis has a tendency to decrease lipid composition levels in the serum and reduce fat deposition in the aorta of high cholesterol diet animals.

Alpha lipoic acid possess dual antioxidant and lipid lowering properties in atherosclerotic-induced New Zealand White rabbit.

There is accumulating data demonstrated hypercholesterolemia and oxidative stress play an important role in the development of atherosclerosis. In the present study, a protective activity of alpha-lipoic acid; a metabolic antioxidant in hypercholesterolemic-induced animals was investigated. Eighteen adult male New Zealand White (NZW) rabbit were segregated into three groups labelled as group K, AT and ALA (n=6). While group K was fed with normal chow and acted as a control, the rest fed with 100 g/head/day with 1% high cholesterol diet to induce hypercholesterolemia. 4.2 mg/body weight of alpha lipoic acid was supplemented daily to the ALA group. Drinking water was given ad-libitum. The study was designed for 10 weeks. Blood sampling was taken from the ear lobe vein at the beginning of the study, week 5 and week 10 and plasma was prepared for lipid profile estimation and microsomal lipid peroxidation index indicated with malondialdehyde (MDA) formation. Animals were sacrificed at the end of the study and the aortas were excised for intimal lesion analysis. The results showed a significant reduction of lipid peroxidation index indicated with low MDA level (p<0.05) in ALA group compared to that of the AT group. The blood total cholesterol (TCHOL) and low density lipoprotein (LDL) levels were found to be significantly low in ALA group compared to that of the AT group (p<0.05). Histomorphometric intimal lesion analysis of the aorta showing less of atheromatous plaque formation in alpha lipoic acid supplemented group (p<0.05) compared to that of AT group. These findings suggested that apart from its antioxidant activity, alpha lipoic acid may also posses a lipid lowering effect indicated with low plasma TCHOL and LDL levels and reduced the athero-lesion formation in rabbits fed a high cholesterol diet.

Palm olein oil produces less lipid peroxidation products than soya bean oil.

The soleus muscles of hyperthyroid rats were used to investigate the effect of palm olein oil and soya bean oil on the production of lipid peroxidation products. It was found that palm olein oil but not soya bean oil significantly decreased malonaldehyde and conjugated diene levels of the soleus muscles of hyperthyroid rats. These findings suggest that palm olein per se produces less lipid peroxidation products than soya bean oil. Such an assay method gives a composite net picture of the propensity of an oil to produce lipid peroxidation products.

The effects of propranolol on skeletal muscle contraction, lipid peroxidation products and antioxidant activity in experimental hyperthyroidism.

1. The mean levels of lipid peroxidation products, namely conjugated diene and malonaldehyde, were increased in the soleus muscles of hyperthyroid cats, while the mean glutathione peroxidase activity was decreased. No corresponding similar changes were noted in the fast extensor digitorum longus muscles and serum. 2. Propranolol administration prevented the increase in conjugated diene level in the soleus muscles of hyperthyroid cat but not the malonaldehyde level. It also prevented the reduction in glutathione peroxidase activity in the slow oxidative soleus muscles of hyperthyroid cats. 3. Maximal twitch tension, subtetanic tension and maximum tetanic tension of soleus and EDL muscles were reduced in hyperthyroid cats. Propranolol administration for 5 weeks to hyperthyroid cats did not prevent the reduction in tension of contractions of these muscles. 4. It is suggested that lipid peroxidation might not be responsible for the myopathy in hyperthyroidism and propranolol administration does not improve skeletal muscle function in hyperthyroid animals.