Studies on hormonal control of serum lipid partition in man

The effects of cholesterol dosage, cortisone, and DCA on total serum cholesterol, lipoproteins, and atherosclerosis in the rabbit

The effects of cholesterol dosage, cortisone, and desoxycorticosterone acetate on total serum cholesterol, lipoproteins, and atherosclerosis were studied over a period of 112 days in thirty-two rabbits. Cholesterol was administered by feeding the rabbits diets containing 0.063, 0.25, and 1.0 per cent cholesterol At intervals measurements were made of total serum cholesterol and of low density lipid and lipoprotein components of three classes, S_f, 5–9, S_f 10–15, and S_f 16–30. All three classes of lipoproteins increased with cholesterol feeding. The total serum cholesterol concentration was linearly related to both the quantity of cholesterol consumed and its concentration in the diet. Lipoprotein and total serum cholesterol concentrations were significantly and equally well correlated with the severity of atherosclerosis. Cortisone administration in the normal rabbit increased the concentrations of total cholesterol and of lipoprotein components of the S_f 10–15 and S_f 16–30 classes, but did not produce atherosclerosis. Cortisone treatment in cholesterol-fed rabbits did not significantly affect the levels of serum lipoproteins, cholesterol concentration, or atherosclerosis produced by a 1.0 per cent cholesterol diet alone. Values for total cholesterol and S_f 5–9 class of lipoproteins in DCA-treated animals were lower than those in controls but the degree of atherosclerosis was not significantly less.

Response of hormones modulating plasma cholesterol to dietary casein or soy protein in minipigs

To elucidate the mechanism mediating the effect of dietary casein or soy protein on serum cholesterol concentrations we followed the endocrine response to the intake of these dietary proteins. The hormones analyzed were those known to modulate serum cholesterol concentration. A 7-wk crossover nutrition study was performed with six adult Göttingen minipigs consuming semisynthetic diets based on either 20 wt% casein or soy isolate. At d 42 and 49, concentrations of six hormones were determined in 22 blood samples taken over the whole day. There were no significant differences in insulin, glucagon, the insulin/glucagon ratio, hydrocortisone or triiodothyronine among dietary groups. In the late postprandial phase (5 h after the meal and later) there were significantly higher growth hormone concentrations in soy-fed animals. At all times of the day, total and free thyroxine concentrations were higher after soy feeding than after casein feeding. On average, total and free thyroxine concentrations were 34 and 26% higher with soy protein feeding than with casein feeding. Our data agree with other reports of protein-dependent changes of thyroid hormones and may explain why different dietary proteins have different effects on serum cholesterol levels in sensitive species.

Hydrocortisone decreases the internalization of low density lipoprotein in cultured human fibroblasts and arterial smooth muscle cells

The effect of hydrocortisone on the cellular low density lipoprotein (LDL) pathway was studied in cultured human skin fibroblasts and arterial smooth muscle cells. Hydrocortisone decreased both uptake and degradation of 125I-LDL, LDL binding, measured at 4 C, was not affected by the hormone. Physiological concentrations of hydrocortisone (4 . 1 X 10(-8) mol/l) resulted in a 30% reduction of LDL uptake and degradation which could not be accounted for by an effect of the hormone on macromolecular synthesis, cell protein or cell number. To test whether the decrease in uptake and degradation of 125I-LDL was due to reduced internalization, the effect of hydrocortisone on the internalization of prebound LDL was determined and found to be decreased. Also, preincubation with unlabelled LDL in the presence of hydrocortisone resulted in less down regulation of LDL receptor activity than when no hydrocortisone was present. An effect of the hormone on bulk phase endocytosis has been excluded, since hydrocortisone did not affect either LDL degradation by receptor negative cells or endocytosis of 14C-sucrose by normal skin fibroblasts. Thus, hydrocortisone impairs LDL catabolism by decreasing the internalization of LDL normally bound to its cell surface receptor. These results may be relevant to the pathogenesis of atherosclerosis in conditions associated with reduced cellular LDL catabolism.

The heart in systemic lupus erythematosus and the changes induced in it by corticosteroid therapy. A study of 36 necropsy patients

The natural history of the cardiovascular manifestations of systemic lupus erythematosus (SLE) have been altered by corticosteroids which exert their own cardiovascular effects. This study describes clinical and necropsy observations in 36 corticosteroid-treated patients with SLE and compares them to necropsy observations in patients with SLE reported before the use of corticosteroid therapy. The 36 patients averaged 32 years of age, and 33 were women. Systemic hypertension was present in 25 (69 per cent) and left ventricular hypertrophy in 23 (64 per cent) patients. Hypertension was twice as common in the 19 patients who received this drug for more than 12 months (average 38 months) than in the 17 patients who received this drug for less than 12 months (average 6 months), and was almost five times more common among our patients than in patients with SLE in the presteroid era. Congestive cardiac failure occurred in 15 patients (43 per cent), eight times more frequent than that reported in noncorticosteroid-treated patients with SLE. Subepicardial and myocardial fat was increased in all 36 patients. Lupus carditis was similar in frequency but differed morphologically in our patients compared to those not treated with corticosteroids. Libman-Sacks-type endocardial lesions, present in 18 (50 per cent) of our patients, were smaller, fewer in number, univalvular rather than multivalvular, and mainly left-sided. Most verrucae were either partly or completely healed, and some were calcified. Pericarditis, present in 19 (53 per cent) patients, was predominantly of the fibrous type. Myocarditis was present in three patients, each of whom also had endocarditis and pericarditis. The lumen of at least one of the three major coronary arteries was narrowed more than 50 per cent by atherosclerotic plaques in 42 per cent of the 18 patients who received corticosteroids for more than 1 year, but in none of the 17 patients who received corticosteroids for less than 1 year. Four of the eight patients with narrowed coronary arteries had myocardial infarcts. Although vital to the management of SLE, corticosteroids have an over-all deleterious effect on the heart. Systemic hypertension and left ventricular hypertrophy appear or, when present, worsen; congestive cardiac failure increases; epicardial apartment of Me

EFFECTS OF ANAPHYLAXIS IN VIVO ON THE LIPID AND PROTEIN CONTENT OF GUINEA-PIG SERUM AND EXTRACELLULAR FLUID OF LUNG TISSUE

Determinations of total cholesterol, phospholipid and glyceride in serum samples obtained from guinea-pigs by cardiac puncture before and after anaphylaxis in vivo indicated reductions occurred in all three fractions after anaphylactic shock. The fall in glyceride was preceded by a rise. Anaphylaxis also induced an accumulation of lipid in oedema fluid in the lungs. These changes were reduced in animals protected from anaphylaxis by pretreatment with a combination of mepyramine and ethanolamine or mepyramine and hydrocortisone.

Hormones, Cholesterol, and Coronary Atherosclerosis

Various hormones have been shown to play an important role in lipid metabolism. Clinical and experimental observations implicate the thyroid, adrenal, gonadal, and pituitary glands in atherogenesis. The evidence is strongest that estrogens play a role in human atherosclerosis. The influence of hypothyroidism requires further study and clarification. Hormones and lipids are obviously not the only factors important in atherogenesis; hypertension, local tissue factors, and altered intravascular coagulation in all probability significantly influence the natural history of the disease.