Rabbit plasma cholesterol

Murphy, K. ]., D. A. Saint, and P. R. Howe. Lack of effect of sugar cane and sunflower seed policosanols on plasma cholesterol in rabbits. Asia Pacific J Clin Nutr 2004 13(Suppl) S69. 

Compactin was shown to lower plasma cholesterol in the rabbit (Watanabe et al., 1981), monkey (Kuroda et al., 1979), and dog (Tsujita et al., 1979). However, some investigators were led astray by the fact that compactin did not lower serum cholesterol in the rat (Fears et al.,... 

Z8. Zilversmit, D. B., Hughes, L. B., and Balmer, J., Stimulation of cholesterol ester exchange by lipoprotein-free rabbit plasma. Biochim. Biophys. Acta 409, 393-398... 

Bursill, C. A., Abbey, M., Roach, P. D. (2007). A green tea extract lowers plasma cholesterol by inhibiting cholesterol synthesis and upregulating the LDL receptor in the cholesterol-fed rabbit. 

Rabbits fed 30 mg/day acarbose showed reduced levels of plasma cholesterol, intermediate-density lipoprotein (IDL) and LDL (Kritchevsky et al., 1990) sudanophilia was reduced by 23% in rabbits fed 7.5 mg/day acarbose and by 43% in rabbits fed 15 or 30 mg/day (Kritchevsky et al., 1990). The decrease in total cholesterol was shown to be a consequence of a significant reduction in LDL cholesterol. Since HDL cholesterol concentrations remained unal-... 

Intravenous administration of 7-ketocholesterol decreased the uptake of cholesterol into rabbit aorta.75 5a-Cholest-8(14)-en-38-ol-15-one suppressed serum cholesterol levels and hepatic cholesterol synthesis. 6 S-8527 significantly reduced serum cholesterol by inhibiting the hepatic synthesis of lipoprotein fractions carrying cholesterol.77 Metformin produced only a slight reduction of plasma cholesterol levels in rabbits fed a high cholesterol diet. However, it markedly decreased aortic cholesterol esters and the atheromatous process, with a simultaneous change in the composition of VLDL.78 79... 

Blood Chemistry. Results of biochemical measurement in blood are shown in Table I. Nifedipine treatment had no effect on plasma cholesterol levels of rabbits maintained on standard diet or 2% cholesterol diet. 

Specific inhibitors of the lipid transfer activity of MTP have been developed as a potential treatment for atherosclerosis based on the premise that inhibition of MTP reduces VLDL secretion. Indeed, MTP inhibitors effectively reduce plasma cholesterol levels by up to 80% in rats, hamsters, and rabbits [13]. However, heterozygosity for MTP deficiency in humans does not diminish plasma lipids or lipoproteins, indicating that a modest reduction in MTP activity does not limit VLDL production. On the other hand, adenovirus-mediated over-expression of MTP in mouse liver increased the secretion, and plasma levels, of TG, apo B100, and apo B48 (D.J. Rader, 1999). MTP inhibitors are not currently used therapeutically, probably because they induce some storage of TG in the liver (steatosis) as a result of the blockage in VLDL secretion. 

Small amounts of cholesterol can also be taken up into the nervous system from the blood following injection of C -cholesterol into 15-day-old rabbits. Once incorporated into the brain, C -cholesterol undergoes slow metabolism and is then retained with little apparent turnover for a period of at least 9 months. Spinal cord cholesterol is equally stable meta-bolically (Fig. 5). In the rabbit, as in the chicken, liver, kidney, and plasma cholesterol undergo quite rapid metabolism. In other experiments (Davison et al., 1959a) brains from rabbits, previously injected with 4-C -cholesterol, were separated into gray and white matter. It became apparent that all the turnover of the C -choIesterol was associated with the gray matter, and that there was little if any metabolism of cholesterol incorporated into the white matter. Since white matter is particularly rich in myelin, this suggested that once cholesterol has been incorporated into... 

Sevanian et al. (1994) applied GLC and LC/TS/MS for the analysis of plasma cholesterol-7-hydroperoxides and 7-ketocholesterol. Analysis of human and rabbit plasma identified the commonly occurring oxidation products, yet dramatic increases in 7-ketocholesterol and cholesterol-5p, 6P-epoxide were observed. The study failed to reveal the presence of choles-terol-7-hydroperoxides, which were either too unstable for isolation, metabolized or further decomposed. The principal ions of cholesterol oxides monitored by LC/TS/MS were m/z 438 (cholestane triol) m/z 401 (cholesterol-7-hydroperoxide) m/z 401 (7-ketocholesterol) m/z 367 (7a-hydroxycholesterol) m/z 399 (cholesta-3,5-dien-7-one) and m/z 385 (choles-terol-5a,6a-epoxide). The major ions were supported by minor ions consistent with the steroid structure. Kamido et al. (1992a, b) synthesized the cholesteryl 5-oxovaleroyl and 9-oxononanoyl esters as stable secondary oxidation products of cholesteryl arachidonate and linoleate, respectively. These compounds were identified as the 3,5-dinitrophenylhydrazone (DNPH) derivatives by reversed-phase LC/NICI/MS. These standards were used to identify cholesteryl and 7-ketocholesteryl 5-oxovaleroyl and 9-oxononanoyl esters as major components of the cholesteryl ester core aldehydes generated by copper-catalysed peroxidation of low-density lipoprotein (LDL). In addition to 9-oxoalkanoate (major product), minor amounts of the 8, 9, 10, 11 and 12 oxo-alkanoates were also identified among the peroxidation products of cholesteryl linoleate. Peroxidation of cholesteryl arachidonate yielded the 4, 6, 7, 8, 9 and 10 oxo-alkanoates of cholesterol as minor products. The oxysterols resulting from the peroxidation of the steroid ring were mainly 7-keto, 7a-hydroxy and 7P-... 

In the first study, control and test groups of six rabbits each (3 male, 3 female) were fed a semipurified diet containing 0.1% cholesterol for 22 wk (Table 18.1). The diet of the test rabbits was augmented with 0.5 g CLA/d. At necropsy, plasma total cholesterol, low density lipoprotein (LDL) cholesterol, and triglyceride (TG) levels tended to be lower than those of controls. Total plasma cholesterol and TG levels (mg/dL) for the CLA-fed group were 1000 and 140 for the control group, they were... 

The addition of lupin seeds to the food of diabetic-hypercholesterolemic rabbits decreases cholesterol levels and postprandial hyperglycemia. Sparteine sulfate administered by intravenous infusirai to normal men increases either basal or glucose-induced secretion sparteine administration to patients with type 2 diabetes causes a fall in plasma glucose levels [56]. 

Intubation of rabbits with 8 mg capsaicin/rabbit (body wt of about 850 g/day for 35 days) did not have any effect with regard to plasma cholesterol, triglyceride, and HDL-cholesterol when they were on a normal diet [108]. In contrast, in rabbits on a 0.5 % cholesterol diet, capsaicin had a beneficial effect in that the plasma cholesterol, triglycerides, and total cholesterol HDL-cholesterol ratio were significantly lower than in animals fed cholesterol only. Turkeys on a 2-3 mg capsaicin/ kg feed for 9 days along with 0.5 % cholesterol had lower total serum cholesterol than the controls [109]. Hypercholesterolemia was produced by feeding a 0.2 % cholesterol-supplemented diet, and capsaicin and dihydrocapsaicin were administered daily via the buccal route at dose of 4 mg per bird for 6 weeks [110]. In... 

Rabbit Mg% Cholesterol in Plasma, Hours After Injection of UA ... 

Mechanism of the hypocholesteremic effect remains in doubt, but may involve inhibition of release of lipoprotein cholesterol from the liver Kritchevsky et al ° found probucol to reduce plasma cholesterol and atheroma fformation in cholesterol-fed rabbits. Probucol apparently was well tolerated in the human studies. 

---