Enkephalins, hunger, and obesity

Obesity and hormonal factors in sleep and sleep apnea

The presence of obesity, defined as weight 20 per cent or more above ideal body weight or increased body fat content, significantly increases risk of pulmonary, cardiovascular, metabolic, and gastrointestinal problems. Obesity is a major cause of shortened life expectancy. While obesity is not essential for the development of the obstructive sleep apnea syndrome, a significant percentage of patients with obstructive sleep apnea are obese. When evaluating these patients who have obstructive sleep apnea, it is important to search diligently for medical problems that are commonly found among the obese. While there is an increased incidence of obese patients among those who have obstructive sleep apnea, the exact reason for this is uncertain. The study of endorphins and enkephalins may expand our understanding of obesity, ventilatory regulation, and obstructive sleep apnea. This may, in fact, enable us to understand better the interrelationship between obesity and obstructive sleep apnea. The role that thyroid hormone, testosterone, and progesterone play in obstructive sleep apnea has also been reviewed. Patients who have obstructive sleep apnea should not be treated with testosterone. All patients given testosterone should be observed quite closely for the possible signs and symptoms of obstructive sleep apnea. Progesterone seems to be of some help in patients who have obesity hypoventilation syndrome. Its effectiveness in patients with obstructive sleep apnea is less clear. The obesity hypoventilation syndrome as described by Burwell is relatively uncommon. Many of the manifestations of the obesity hypoventilation syndrome, however, are found in patients with obstructive sleep apnea. The recognition that the symptoms stem from underlying obstructive sleep apnea offers great potential for therapy. Weight reduction is valuable therapy for patients with obesity and pulmonary dysfunction, obesity and obstructive sleep apnea, and obesity hypoventilation syndrome. Weight reduction and weight maintenance, while difficult, are essential in patients with obesity, obesity and obstructive sleep apnea, and the hypoventilation syndrome. Obesity should be viewed as a medical problem deserving medical attention and long-term medical follow-up.

A 50000-dalton anorexigenic protein from urine

A potent, homogeneous, 50 kDa protein which transiently depresses food intake of rats up to 24 h after injection was isolated from rat urine. It was prepared from an ethanolic benzoic acid precipitate of urine. The material was subjected to DEAE-Sephacel chromatography, whereupon four fractions (DEAE pools a, b, c, and d) were obtained. The latter three contained anorexigenic activity. DEAE pools b and c were subjected to further purification on columns of Sephacryl S-300 eluted with buffer containing 8 M urea. One of the subfractions of DEAE pool b contained only one protein as judged by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This protein had a molecular weight of 50,000 and was active in reducing 24 h food intake at a dose of 130 micrograms/100 g bodyweight.

Impaired prolactin secretion in obese patients

To investigate a possible hypothalamic alteration in obesity, we have studied the pattern of PRL secretion in response to insulin hypoglycemia, arginine infusion and TRH injection in 12 grossly obese patients and in 12 normal-weight controls. In the obese patients, PRL secretion was significantly lower than in normal subjects in response to insulin hypoglycemia and arginine infusion, while it was not significantly different from that in controls in response to TRH. The mean +/- SE values of the areas subtended by the PRL curves in the 3 above tests were 54.7 +/- 155.81 vs 3677.3 +/- 520.30 ng/2h, p less than 0,01, 210.3 +/- 148.93 vs 1034.8 +/- 203.15 ng/2h, p less than 0.05 and 1476.8 +/- 275.13 vs 2148.6 +/- 682.06 ng/2h, NS, respectively, in the obese and in controls. These results are compatible with the concept of impaired hypothalamic control of PRL secretion in obesity, although it is still unclear what role this may play in the pathogenesis of this disorder.