Elevation of serum cholesterol levels in mice by the antioxidant butylated hydroxyanisole

Effects of butylated hydroxyanisole on the development and functions of reproductive system in rats

Butylated hydroxyanisol (BHA) is a widely used antioxidant for long preservation of food products, cosmetics and pharmaceuticals. Although BHA is generally recognized as safe, it is classified as a suspected endocrine-disrupting compound. We investigated the effects of BHA on reproductive function and development by the treatment of mature male and female SD rats (F0) through pre-gestation, gestation and lactation period and of their offspring (F1) until 13 weeks old via gavage with BHA 0 (corn oil, vehicle control), 10, 100 and 500 mg/kg bw/day. Organ weights of liver, adrenal gland and thyroid gland of F0 rats were increased by BHA 500 mg/kg but those of spleen and ventral prostate were decreased without significant difference in terminal body weight. Reduced serum testosterone and thyroxine (T4) were observed with dose-dependent manner in F0 male rats. Mating rate was decreased and cohabitation duration for conception was longer without differences in the number, motility and morphology of sperm by BHA 500 mg/kg. Body weight of F1 offspring was significantly decreased with change of relative weight of liver and brain by BHA 500 mg/kg at PND21. Sexual maturation indicated by vaginal opening and preputial separation was delayed by BHA 500 mg/kg. The weights of liver and adrenal gland were increased while those of spleen, vagina, testes and ventral prostate were decreased in F1 rats exposed to BHA 100 or 500 mg/kg for 13 weeks. Also, BHA 500 mg/kg reduced the velocity of sperm motion and number with smaller-sized sperm head in F1 male rats and slightly shortened estrous cycle length with higher frequency of estrus and lower frequency of diestrus stages in F1 female rats. Lower serum T4 and testosterone contents with higher serum cholesterol levels were also observed by BHA 500 mg/kg. Increased follicular cell height, and exfoliated and vacuolated follicular epithelial cells were observed in thyroids of F1 female and males rats exposed to BHA 500 mg/kg. This study elucidates that high dose of BHA induce weak dysfunction and underdevelopment of reproductive system of male and female rats with the change of T4 and testosterone levels, sex organ weights and sexual maturation and histological lesions of thyroid gland.

Effects of dietary phenolic compounds on tocopherol, cholesterol, and fatty acids in rats

The effects of the phenolic compounds butylated hydroxytoluene (BHT), sesamin (S), curcumin (CU), and ferulic acid (FA) on plasma, liver, and lung concentrations of alpha- and gamma-tocopherols (T), on plasma and liver cholesterol, and on the fatty acid composition of liver lipids were studied in male Sprague-Dawley rats. Test compounds were given to rats ad libitum for 4 wk at 4 g/kg diet, in a diet low but adequate in vitamin E (36 mg/kg of gamma-T and 25 mg/kg of alpha-T) and containing 2 g/kg of cholesterol. BHT significantly reduced feed intake (P < 0.05) and body weight and increased feed conversion ratio; S and BHT caused a significant enlargement of the liver (P < 0.001), whereas CU and FA did not affect any of these parameters. The amount of liver lipids was significantly lowered by BHT (P < 0.01) while the other substances reduced liver lipid concentrations but not significantly. Regarding effects on tocopherol levels, (i) feeding of BHT resulted in a significant elevation (P< 0.001) of alpha-T in plasma, liver, and lung, while gamma-T values remained unchanged; (ii) rats provided with the S diet had substantially higher gamma-T levels (P < 0.001) in plasma, liver, and lung, whereas alpha-T levels were not affected; (iii) administration of CU raised the concentration of alpha-T in the lung (P < 0.01) but did not affect the plasma or liver values of any of the tocopherols; and (iv) FA had no effect on the levels of either homolog in the plasma, liver, or lung. The level of an unknown substance in the liver was significantly reduced by dietary BHT (P < 0.001). BHT was the only compound that tended to increase total cholesterol (TC) in plasma, due to an elevation of cholesterol in the very low density lipoprotein + low density lipoprotein (VLDL + LDL) fraction. S and FA tended to lower plasma total and VLDL + LDL cholesterol concentrations, but the effect for CU was statistically significant (P < 0.05). FA increased plasma high density lipoprotein cholesterol while the other compounds reduced it numerically, but not significantly. BHT, CU, and S reduced cholesterol levels in the liver TC (P < 0.001) and percentages of TC in liver lipids (P < 0.05). With regard to the fatty acid composition of liver lipids, S increased the n-6/n-3 and the 18:3/20:5 polyunsaturated fatty acids (PUFA) ratios, and BHT lowered total monounsaturated fatty acids and increased total PUFA (n-6 + n-3). The effects of CU and FA on fatty acids were not highly significant. These results suggest some in vivo interactions between these phenolic compounds and tocopherols that may increase the bioavailability of vitamin E and decrease cholesterol in rats.

Effect of the plant compound indole-3-carbinol on hepatic cholesterol homoeostasis

The aim of this study was to elucidate the effects of the compound indole-3-carbinol (I3C), which is found in cruciferous vegetables, on hepatic cholesterol homoeostasis and metabolism in male CD-1 mice. Oral administration of 500 and 750 mg I3C/kg/day to mice for 1 wk resulted in increased liver mass and microsomal protein content. Hepatic microsomal cholesterol levels were not significantly altered following treatment with 100 and 250 mg I3C/kg/day, but were significantly decreased following treatment with 500 and 750 mg/kg/day. Conversely, the lower doses of I3C administered decreased serum cholesterol levels whereas the higher doses of I3C had no effect on this parameter. Alterations in cholesterol homoeostasis by I3C were not related to liver hypertrophy, since administration of phenobarbital to mice increased liver size, but had no significant effect on hepatic microsomal or serum cholesterol levels. Activities of the hepatic enzymes cholesterol ester hydrolase and cholesterol 7 alpha-hydroxylase were not altered by I3C. However, 500 and 750 mg I3C/kg/day elevated the activity of hepatic acyl-CoA:cholesterol acyltransferase (ACAT), the enzyme responsible for the formation of hepatic cholesteryl esters. These results demonstrate that (a) I3C lowers serum cholesterol levels at concentrations that have no discernible effect on hepatic cholesterol homoeostasis, and (b) at higher doses of I3C, hepatic microsomal cholesterol levels are significantly lowered and ACAT activity is significantly elevated. These latter effects are not accompanied by changes in serum cholesterol levels and may represent compensatory mechanisms to restore cholesterol homoeostasis in the body. Mechanisms responsible for the effects of I3C on cholesterol homoeostasis are proposed.

Hypocholesterolemic properties of plant indoles. Inhibition of acyl-CoA:cholesterol acyltransferase activity and reduction of serum LDL/VLDL cholesterol levels by glucobrassicin derivatives

Studies were undertaken to investigate the effects of the plant compound indole-3-carbinol (I3C) and its acid condensation products, which are generated in the stomach following ingestion of I3C, on cholesterol homeostasis in mice. Individual acid condensation products were synthesized and purified by HPLC. In vitro experiments revealed that several of the acid condensation products effectively inhibited the enzyme acyl-CoA:cholesterol acyltransferase (ACAT), which is responsible for the conversion of free cholesterol to the cholesteryl ester, at micromolar concentrations. Since the inhibition of ACAT in vivo should reduce serum cholesterol levels, I3C was administered to mice, and the effects on serum cholesterol levels were evaluated. Total serum cholesterol levels were elevated by 29% in mice provided a 3% cholesterol-supplemented diet, but this elevation was attenuated significantly (P < or = 0.05) by approximately 50% when I3C (100 mg/kg/day) was added to this diet. This effect of I3C was entirely on low density lipoprotein (LDL)/very low density lipoprotein (VLDL) cholesterol, which was lowered significantly (P < or = 0.05) by approximately 30%. In summary, I3C lowered serum LDL/VLDL cholesterol levels in mice, and this effect was likely mediated by the inhibition of ACAT by some of the acid condensation products of I3C. These results provide a possible mechanism by which I3C-rich vegetables lower serum cholesterol levels.