Regeneration of adrenal cortical tissue after adrenal autotransplantation.

This study tested the possibility of adrenal autotransplantation in rats. Since the cortex and the medulla of the adrenal gland were from different origin embryologically, either whole adrenal glands (ADR), or capsule and cortex (CAP) or medulla (MED) were autotransplanted in the subcutaneous tissue. The functions of regenerated adrenal nodules were tested by measuring plasma corticosterone levels every fortnight. At the end of 9 weeks the rats were exposed to hypovolemic shock followed by naloxone injection to reverse the shock response. Results showed that rats transplanted with either cortex or whole adrenal started secreting corticosterone at 5 weeks post-transplantation (107.73 +/- 21.98 ng/ml, 126.04 +/- 48.41 ng/ml, respectively). Corticosterone levels increased to the value which were not significantly different from control by 9 weeks post-transplantation. However, rats transplanted with adrenal medulla showed very low corticosterone levels. Nine weeks post-transplantation, the mean blood pressure (MBP) of the CAP group was 135 +/- 13 mmHg and was not significantly different from sham-operated controls, whereas MBP of MED group was significantly lower than sham-operated animals (99 +/- 11 mmHg versus 141 +/- 9 mmHg). The MBP of the ADR group was also lower compared to sham-operated controls (112 +/- 17 mmHg P < 0.05). The MBP of the adrenal group was not statistically significant compared to the CAP group. After 1% body weight haemorrhage, the MBP decreased significantly in ADR (45 +/- 5 mmHg, P < 0.05) and MED group (36 +/- 9 mmHg, P < 0.001) compared to sham-operated rats (78 +/- 11 mmHg) but not in the CAP (56 +/- 9 mmHg). It was concluded that autotransplanted whole adrenal or adrenocortical tissues survived subcutaneously and produced sufficient corticosterone to alleviate haemorrhagic shock. Adrenal medullary tissue failed to regenerate subcutaneously and the presence of adrenal medullary tissue may suppressed the growth of transplanted adrenal gland.

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.

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.