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Altered adrenergic control in hypercholesterolemia
J Ohanian1, R J Nicolosi, S F Vatner
1Department of Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Insights
Alpha 1-adrenergic receptor inhibition, used for hypertension, significantly reduced total cholesterol and VLDL+LDL cholesterol in hypercholesterolemic monkeys. This suggests a dual benefit for vascular and lipid health.
Area of Science:
- Cardiovascular Science
- Pharmacology
- Metabolic Research
Background:
- Hypercholesterolemia and atherosclerosis alter vascular reactivity, with enhanced vasoconstriction via serotonergic mechanisms.
- Adrenergic mechanisms' role in vascular changes remains unclear, but hypertension therapies like beta-blockers and diuretics can increase serum lipids.
- Elevated lipids may contribute to vascular abnormalities in hypertensive patients.
Purpose of the Study:
- To investigate the effects of alpha 1-adrenergic receptor inhibition on plasma lipid levels and vascular reactivity.
- To examine the potential of prazosin, an alpha 1-adrenergic antagonist, in managing hypercholesterolemia.
Main Methods:
- Preliminary laboratory study using hypercholesterolemic monkeys.
- Administration of alpha 1-adrenergic receptor inhibition (prazosin).
- Monitoring of plasma cholesterol levels (total, VLDL+LDL) and vascular reactivity.
Main Results:
- Prazosin treatment led to significant reductions in total cholesterol.
- A notable decrease was observed in the very-low-density lipoprotein (VLDL) + low-density lipoprotein (LDL) cholesterol fraction.
- Alpha 1-adrenergic receptor inhibition demonstrated a beneficial effect on lipid profiles.
Conclusions:
- Alpha 1-adrenergic receptor inhibition, exemplified by prazosin, offers a dual therapeutic advantage.
- Beyond its antihypertensive effects, it positively impacts lipid metabolism by lowering cholesterol.
- This suggests a potential role in managing patients with both hypertension and hypercholesterolemia.
Abstract:
Vascular reactivity is altered by hypercholesterolemia and atherosclerosis. Animal studies have shown that serotonergic mechanisms of vasoconstriction are enhanced, while the changes with adrenergic mechanisms are still equivocal. Serum lipids are increased with beta-blocker and diuretic therapy for hypertension. Thus, the increase in serum lipids may be responsible for both structural and functional abnormalities of the vascular system in hypertensive patients. In contrast, recent reports have suggested that alpha 1-adrenergic receptor inhibition, useful in hypertension therapy, may exert a beneficial effect on plasma lipids. We have also collected preliminary data in our laboratory examining the effects of alpha 1-adrenergic receptor inhibition with prazosin on plasma cholesterol levels and vascular reactivity in monkeys with hypercholesterolemia. We observed large reductions in both total cholesterol and the very-low-density lipoprotein (VLDL) + low-density lipoprotein (LDL) fraction of cholesterol in these animals during treatment with prazosin. Thus, in addition to its sympatholytic action on the vasculature, alpha 1-adrenergic receptor inhibition appears to exert a beneficial effect in reducing total cholesterol levels.