Neurotransmitters involved in the central regulation of the cardiovascular system

Serotonin Receptor 2A (HTR2A) Gene Polymorphisms Are Associated with Blood Pressure, Central Adiposity, and the Metabolic Syndrome

BACKGROUND

Although the etiology of the metabolic syndrome remains unclear, recent evidence suggests that dysregulation of brain serotonergic activity may partly underlie the covariation of risk factors comprising the syndrome. In addition, prior studies have shown polymorphisms in the serotonin 2A receptor (HTR2A) gene to be associated with two syndrome components, hypertension and central adiposity. We conducted a study to confirm associations of HTR2A polymorphisms with elevated blood pressure and central adiposity and tested for association between these polymorphisms and the metabolic syndrome.

METHODS

The study sample included 934 unrelated individuals of European ancestry. We tested for association of two HTR2A polymorphisms, one in the promoter: (-1438[G/A]) and one in the first intron (2416 [C/T]), individually and as a diplotype, with elevated blood pressure, central adiposity, elevated fasting glucose, triglycerides, high density lipoprotein (HDL) cholesterol and presence of the metabolic syndrome, as defined by the American Heart Association/National Heart, Lung and Blood Institute (AHA/NHLBI) Scientific Statement Executive Summary.

RESULTS

Confirming previous reports, elevated blood pressure (>130/85 mm Hg) was associated with both the -1438 GG and 2416 TT genotypes and the GG/TT diplotype (ORs = 1.39-1.76); high waist circumference was associated with -1438 GG genotype only (OR = 1.57). In addition, both the -1438 GG and 2416 TT genotypes, and the GG/TT diplotype, predicted presence of the metabolic syndrome (ORs = 1.44-1.77). Fasting glucose, triglyceride and HDL cholesterol were not associated with either polymorphism.

CONCLUSIONS

Elevated blood pressure, central adiposity, and the metabolic syndrome are associated with polymorphisms in HTR2A gene.

Psychologic factors as precursors to hypertension

The possibility that certain psychologic factors lead to hypertension has been considered by many investigators over the past 60 years, but prospective studies with suitable methods to evaluate this hypothesis were not available for analysis until the 1990s. There are now five large longitudinal studies demonstrating a relation between symptoms of anxiety or depression and subsequent hypertension incidence. Anger expression, long considered a major psychologic factor in hypertension, has been studied less extensively, and the findings to date are less consistent. While some evidence supports the biological plausibility of psychologic factors as risk factors for hypertension, biobehavioral mechanisms explaining the relationship have not been adequately explored. The results of these recent studies may lead to new intervention trials specifically selecting hypertensive patients with anxiety or depression for treatment with stress reduction or other appropriate psychologic therapies. Such studies would further contribute to the evaluation of anxiety and depression as risk factors for hypertension.