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18/08/2006

Scientists from the University of Navarra analyze the relationship between obesity and hypertension by means of the hormone leptin

The "Journal of Hypertension" has published the research results of this joint project of the CIMA and the University Hospital

Scientists of the Center for Applied Medical Research (CIMA) and of the University Hospital of the University of Navarra have analyzed the role of leptin, a hormone secreted by fat cells, for the purpose of deepening our understanding of hypertension associated with obesity.

The Journal of Hypertension has included the resulting article in its latest issue. The authors of the article are Amaia Rodríguez, Gema Frühbeck, Javier Gómez-Ambrosi, Victoria Catalán, Neira Sáinz, Javier Díez, Guillermo Zalba and Ana Fortuño. The research was a joint effort of the Area of Cardiovascular Sciences of the CIMA and of the Metabolic Research Laboratory of the University Hospital.

As Amaia Rodríguez explained, leptin offers a dual benefit: it acts upon the brain, diminishing appetite and body weight, and contributes to regulating arterial pressure. Nevertheless, she added that “it does not perform its function in obese and hypertensive individuals. Although these persons have high levels of this hormone in their blood, it does not function correctly.”

Metabolic syndrome

The study concluded that this resistance to leptin originates when the hormone loses its capacity to relax the blood vessels, and to counteract in the aorta the effects of angiotensin II, which is a potent blood vessel constrictor that is involved in the development of hypertension. “This augments the sympathetic activity which the hormone produces in the brain, favoring the appearance of the disease,” the biologist stated.

During this research project, it was confirmed that in spontaneously hypertensive rats, leptin loses its ability to dilate blood vessels, despite the fact that these animals have a larger quantity of leptin receptors in the aorta. The rats presented certain alterations which are known as the metabolic syndrome: hypertension, weight gain, and resistance to insulin (related to diabetes). “The high levels of leptin which are encountered aid in the development of hypertension, which confirms the findings of other authors,” emphasized Amaia Rodríguez.

University Hospital of the University of Navarra