Polycystic ovary syndrome (PCOS), the most common cause of female infertility in the U.S., is a complicated endocrine-related condition with many characteristics, including increased risk for diabetes and obesity, irregular menstrual cycles, ovarian cysts, excessive hair growth, and insulin resistance. Insulin resistance also plays a role in the metabolic syndrome. In the study "Prevalence and Characteristics of the Metabolic Syndrome in Women with Polycystic Ovary Syndrome," researchers hypothesized that the metabolic syndrome is more prevalent in women with PCOS, and that women with both conditions would exhibit more hormonal and menstrual cycle irregularity than women with PCOS only.
Through a retrospective study that reviewed medical charts stemming back three years for 161 women, the study investigators successfully identified 106 women (46 women with PCOS and the metabolic syndrome; 60 women with PCOS alone) for participation and analysis. The study revealed that women with PCOS are nearly two times as likely to have the metabolic syndrome in comparison with women without PCOS in the general population. Women demonstrating characteristics of both PCOS and the metabolic syndrome were found to also have more severe insulin resistance. The researchers concluded that the metabolic syndrome and its related conditions, therefore, are common in women with PCOS, putting these women at even greater increased risk for cardiovascular disease.
Peptide YY (PYY) is a hormone that reduces food intake; ghrelin is a hormone that stimulates one's appetite and increases hunger; and glucose-dependent insulinotropic polypeptide (GIP) is a hormone that regulates glucose levels to maintain balance. All three hormones are produced mainly in the gut and thought to affect energy balance. Despite the increasing prevalence of both childhood obesity and adolescent anorexia, there has been little investigation into the roles these three gut-hormones play in hunger response among adolescents. However, in the study "Ghrelin, PYY, GIP and Hunger Responses to a Mixed Meal in Anorexic, Obese and Control Female Adolescents," researchers aimed to evaluate the role of these hormones on satiety, or the feeling of fullness, among 30 female adolescents who were either anorexic, of normal weight, or obese. Study participants were asked to consume a liquid meal consisting of a mixture of 55 percent carbohydrates, 25 percent protein and 20 percent fat. Researchers took a blood sample from each of the trial participants at baseline and then periodically up until 240 minutes following the meal.
The study revealed that PYY does not increase following a meal in obese adolescents, suggesting that since the hormone is not acting to reduce food intake (i.e., the subject is not feeling full), it may actually contribute to increases in caloric intake and, in turn, weight gain in these subjects. Similar to findings relating to adults, ghrelin concentrations in both anorexic and obese adolescents were found to be increased compared to their normal weight counterparts. This finding caused researchers to conclude that it is unlikely that ghrelin plays a causal role in the development of either anorexia or obesity. Finally, a marked decrease in GIP response to the meal was noted in the anorexic subjects only, leading researchers to assume that expression of GIP may in fact play a role in anorexia. Overall, the researchers concluded that additional research into the functionality of the three gut hormones evaluated in this study - PYY, ghrelin and GIP - will further help in the understanding of hunger response among adolescents of all weights.
Surprise Finding - Diabetes and Vascular Disease Risks
Cholesteryl ester transfer protein (CETP) is a plasma enzyme that is involved in transporting and clearing cholesterol from peripheral tissues such as those found in the liver and in adipose depots. CETP is a mediator of vascular disease and a target for many vascular disease treatments, as both increased and decreased expression of the enzyme alike have been linked to elevated risk and incidence of vascular disease. Previous research indicates that plasma CETP levels are commonly elevated in obese patients, increasing the patients' risk for vascular disease. However, evaluations of obese women with type 2 diabetes have shown that this elevation is typically eliminated. Whether the difference in CETP level expression in obese women with or without diabetes is beneficial or detrimental has yet to be determined. In the study, "Suppression of Hepatic CETP Expression in Obese Humans With the Development of Type 2 Diabetes Mellitus," researchers investigated CETP activity in the plasma of obese men and women with and without type 2 diabetes to determine whether the effect diabetes has on metabolizing CETP is gender specific. CETP expression in obese diabetic men has not yet been studied until now. The study investigators assumed that suppression of CETP would occur in all individuals with type 2 diabetes regardless of gender - an assumption proven through this investigation.
The study also found that diabetic obese patients have lower levels of plasma CETP activity and mass than obese patients without diabetes due, in part, to a different form of CETP mRNA found in the patients' liver. The researchers found that CETP levels were lowest when measured in the liver of the diabetic obese subjects, leading them to hypothesize that the way the liver expresses CETP might be the key to the suppression of the enzyme in diabetics versus their non-diabetic counterparts. These findings provide sound insight into the regulation of CETP expression in diabetic obese patients and will have implications on the development of future treatments for vascular disease. Although the effect of diabetes on this enzyme, CETP, appears beneficial, study investigators warn that additional research is needed to further understand the actual vascular risks associated with both diabetes and obesity.
See these studies and more in the upcoming issue of JCE&M from The Endocrine Society. To interview an author or to obtain a copy of the studies discussed above, contact Tadu Yimam of The Endocrine Society at media@endo-society.org
Other Happening/Events
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Now Available - The Endocrine Society Weighs In: A Handbook on Obesity in America (2005)
The Endocrine Society and The Hormone Foundation recognize the importance of addressing obesity and the impact it has on the lives and overall health of Americans. In early 2004, our two organizations developed a handbook designed specifically for media, The Endocrine Society Weighs In: A Handbook on Obesity in America. This handbook was developed to serve as a comprehensive, easy-to-use resource outlining the scope of the obesity problem facing our nation. An updated edition of the handbook is available at www.obesityinamerica.org
A limited supply of hardcopy editions of the 2005 edition of The Endocrine Society Weighs In: A Handbook on Obesity in America may be available. Please contact Tadu Yimam at media@endo-society.org for more information.
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Exciting News From The Endocrine Society: ENDO 2005
The Endocrine Society's 87th Annual Meeting, ENDO 2005, will be held in San Diego, CA, Saturday, June 4 through Tuesday, June 7. This year's ENDO, the world's largest gathering of endocrinologists, will focus on "Pathways to Discovery and Practice," highlighting how advances in basic endocrine research have been translated into new innovative therapies for endocrine diseases. Learn how the role of the endocrinologist can be described as practicing medicine from "bench to bedside" - being on the forefront of medical research into the mechanisms of endocrine-related disease, defining underlying causes and effects of endocrine disease through this research and translating those findings into management and treatment regimens.
Specific obesity-related symposia of interest include:
- Obesity: What Can We Do About It? - Presented by George Bray, Pennington Biomedical Research Center
- Physical Activity and Weight Management: How Much is Enough? - Presented by Holly Wyatt, University of Colorado Health Sciences Center
- PPARpan Agonists for T2D & the Metabolic Syndrome - Presented by William Oliver, Glaxo-SmithKline
New this year, ENDO will feature four full days of scientific programming with 69 symposia, 144 Meet-the-Professor, 58 oral sessions and 78 poster sessions presenting the latest and most cutting-edge clinical and basic research in all endocrine topic areas, including:
- Drug discovery
- Endocrine Disrupting Chemicals
- Steroid metabolism
- Stem cell therapy
- Breast cancer
- Control of energy homeostasis
- Hormone action
- Signal transduction
- And more!
Receive complimentary registration as a credentialed member of the press!
Information about ENDO 2005, including details regarding press conferences and other media events planned for the meeting, is available online at www.endo-society.org/media/pressroom.cfm
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If you have any questions about this issue of The Endocrine Edge or The Endocrine Society, please contact Tadu Yimam of The Endocrine Society at media@endo-society.org.
