Baku, August 24 (AZERTAC). Reporting at the 6th International Congress of Neuroendocrinology in Pittsburgh, Polish researchers who studied women aged 20 to 102 suggest a small protein derived from fat tissue may be an important determinant of longevity. Other research indicates boosting growth hormone may allow the elderly to live independently longer.

Boosting production of growth hormone may extend the time that elderly men and women can live independently, suggests a study of an investigational oral medication led by George R. Merriam, M.D., professor of medicine at the University of Washington/VA Puget Sound Health Care System, and colleagues.

Aging is characterized by a progressive decline in muscle mass, strength and exercise capacity, often leading to frailty and the inability for living independently. Since growth hormone (GH) secretion also declines with age and many age-related changes resemble those seen in GH deficiency, the researchers are investigating the potential physical and endocrine effects of stimulating GH in older adults.

In this controlled trial involving 395 men and women aged 65 to 84 with mild limitations in their physical functioning, participants received either placebo or various oral doses of the growth hormone stimulator (GHS) capromorelin, an investigational medication discovered and developed by Pfizer Global Research and Development. Compared to placebo, GHS at any dose prompted an acute GH peak and an increase in overnight GH secretion - increases that were sustained throughout a 12-month treatment period.

A protein derived from fat tissue may be an important determinant of longevity, suggests a study of 133 women, including 25 aged 100 to 102, whom researchers found had notably higher levels of adiponectin circulating in their blood. Adiponectin is a peptide that has anti-inflammatory properties, helps keep vessels clear of fatty deposits and plays an important role in metabolism, particularly of lipids and glucose. Insufficient levels of adiponectin are thought to contribute to obesity, insulin resistance, diabetes or the formation of lipid deposits in the arteries, collectively known as symptoms of metabolic syndrome.

The study, which was conducted by Agnieszka Baranowska-Bik, M.D., and colleagues from the Medical Centre of Postgraduate Education, Warsaw, Poland, looked at blood plasma concentrations of adiponectin in four groups of women: the 25 centenarians, 26 women aged 64 to 67, 45 between the ages of 20 and 43, and 37 obese women aged 26 to 54. Compared to the other groups, the oldest old had significantly higher concentrations of adiponectin as well as much lower levels of both leptin and insulin. Moreover, the oldest-old women scored better with respect to insulin resistance and total cholesterol. Compared to the obese women, who, as expected, had more evidence of metabolic disturbances, the centenarians had significantly fewer signs of hypertension and other symptoms characteristic of metabolic syndrome. Dr. Baranowska-Bik stops short of calling adiponectin the fountain of youth, but the results of this study, she argues, provide evidence that adiponectin may play an important role in longevity.