Future directions in lipid therapies

Attributional styles and stress-related atherogenic plasma lipid reactivity in essential hypertension

OBJECTIVE

Hypertension and an atherogenic lipid profile are known risk factors for coronary heart disease (CHD). Hypertensives show greater changes in atherogenic plasma lipids to acute stress than normotensives. In this study, we investigated whether attribution of failure is associated with lipid stress reactivity in hypertensive compared with normotensive men.

METHODS

18 normotensive and 17 hypertensive men (mean±SEM; 45±2.2 years) underwent an acute standardized psychosocial stress task that can be viewed as a situation of experimentally induced failure. We assessed external-stable (ES), external-variable (EV), internal-stable (IS), and internal-variable (IV) attribution of failure and psychological control variables (i.e. extent of depression and neuroticism). Moreover, total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C), and norepinephrine were measured immediately before and several times after stress.

RESULTS

ES moderated TC- and LDL-C-stress reactivity in hypertensives as compared to normotensives (interaction mean arterial pressure [MAP]-by-ES for TC: F=3.71, p=.015; for LDL-C: F=3.61, p=.016). TC and LDL-C levels were highest in hypertensives with low ES immediately after stress (p≤.039). In contrast, hypertensives with high ES did not differ from normotensives in TC and LDL-C immediately after stress (p's>.28). Controlling for norepinephrine, depression, and neuroticism in addition to age and BMI did not significantly change results. There were no significant associations between lipid baseline levels or aggregated lipid secretion and IS, IV, or EV (p's>.23).

CONCLUSION

Our data suggest that ES may independently protect from elevated lipid stress reactivity in hypertensive individuals. ES thus might be a protective factor against CHD in hypertension.

Changes in plasma lipids with psychosocial stress are related to hypertension status and the norepinephrine stress response

Hypertension is a known risk factor for cardiovascular disease. Hypertensive individuals show exaggerated norepinephrine (NE) reactivity to stress. Norepinephrine is a known lipolytic factor. It is unclear if, in hypertensive individuals, stress-induced increases in NE are linked with the elevations in stress-induced circulating lipid levels. Such a mechanism could have implications for atherosclerotic plaque formation. In a cross-sectional, quasi-experimentally controlled study, 22 hypertensive and 23 normotensive men (mean +/- SEM, 45 +/- 3 years) underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience. We measured plasma NE and the plasma lipid profile (total cholesterol [TC], low-density-lipoprotein cholesterol [LDL-C], high-density-lipoprotein cholesterol, and triglycerides) immediately before and after stress and at 20 and 60 minutes of recovery. All lipid levels were corrected for stress hemoconcentration. Compared with normotensives, hypertensives had greater TC (P = .030) and LDL-C (P = .037) stress responses. Independent of each other, mean arterial pressure (MAP) upon screening and immediate increase in NE predicted immediate stress change in TC (MAP: beta = .41, P = .003; NE: beta = .35, P = .010) and LDL-C (MAP: beta = .32, P = .024; NE: beta = .38, P = .008). Mean arterial pressure alone predicted triglycerides stress change (beta = .32, P = .043) independent of NE stress change, age, and BMI. The MAP-by-NE interaction independently predicted immediate stress change of high-density-lipoprotein cholesterol (beta = -.58, P < .001) and of LDL-C (beta = -.25, P < .08). We conclude that MAP and NE stress reactivity may elicit proatherogenic changes of plasma lipids in response to acute psychosocial stress, providing one mechanism by which stress might increase cardiovascular risk in hypertension.

Double-blind, randomized feedback control fails to improve the hypocholesterolemic effect of a plant-based low-fat diet in patients with moderately elevated total cholesterol levels

OBJECTIVE

To determine whether the cholesterol-lowering effect of a plant-based low-fat diet can be improved by a flexible control design that controls the extent of fat reduction based on the individual response of blood cholesterol.

DESIGN

Randomized, double-blind intervention study.

SETTING

A hotel in Prerow, Germany.

SUBJECTS

A total of 32 participants (21 female and 11 male participants) with total cholesterol level > 5.7 mmol/l.

INTERVENTION

The control group consumed a plant-based low-fat diet with constantly 20% of energy as fat; the intervention group received a diet with either 20 or 15% of energy as fat, depending on the serum cholesterol response of the preceding week. A flexible control design based on the individual cholesterol response during a run-in period of 1 week was used within a low-fat intervention.

RESULTS

During the run-in period, the consumption of a plant-based low-fat diet led to a reduction in total cholesterol by 18+/-6 mmol/l (P < 0.001), in LDL cholesterol by 19+/-9 mmol/l (P < 0.001) and triglycerides by 13+/-3 mmol/l (P < 0.001). During the feedback control period, an additional reduction in total cholesterol by 13+/-8 (P < 0.001) and in LDL cholesterol by 17+/-11 (P < 0.001) was observed compared to 15+/-15 and 7+/-18 in the control group. The effect of an additional feedback control was only marginal and not statistically significant compared to the effect of the low-fat diet alone.

CONCLUSIONS

On a level of fat intake already reduced to 20% of energy, the use of a feedback control to adapt the fat content of the diet depending on the individual serum cholesterol response was not more effective in reducing blood cholesterol levels than a plant-based low-fat diet alone.

Hepatic expression of PPARalpha, a molecular target of fibrates, is regulated during inflammation in a gender-specific manner

Dyslipidemia, inflammation and gender are major risk factors in cardiovascular disease. Here we show that hepatic expression of Peroxisome proliferator-activated receptor alpha (PPARalpha), a nuclear receptor that regulates lipid metabolism and inflammation, is regulated in a gender-specific manner during lipopolysaccharide (LPS)-induced systemic inflammation. Immediately following LPS-induced systemic inflammation, hepatic PPARalpha mRNA level decreased dramatically in mice. It was restored to baseline within 24 h in females but remained below baseline for >72 h in male mice. In gonadectomized mice of both sexes, PPARalpha mRNA level was restored to baseline within 48 h after the initial decrease.

Hypolipemic effect of Cyclocarya paliurus (Batal) Iljinskaja in lipid-loaded mice

We investigated the inhibitory effect of Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) extract on postprandial hyperlipemia in mice. A single oral administration of C. paliurus extract (250 mg/kg) suppressed an increase in plasma triacylgycerol (TG) levels when fed with 5 ml/kg of lard and olive oil. The inhibition rates were 28.6% and 24.1%, respectively, but free fatty acid (FFA) levels in plasma were not significantly affected as compared with control group mice. In addition, C. paliurus extract showed inhibitory activity toward pancreatic lipase, a key enzyme of dietary TG absorption, with an IC(50) of 9.1 microg/ml in vitro. Our results suggested that the hypolipemic action of C. paliurus extract was probably interrelated with suppression of the activity of digestive lipase, and as a result, the blood lipid level was reduced.