Sex and gender in cardiovascular-renal physiology and pathophysiology

Gender influences the prevalence and progression rate of many renal diseases, such as polycystic kidney disease (PKD).

The physiology behind gender differences and renal disease is still uncertain, but the distinct characteristics of male and female kidney size, along with diet and the presence of hypertension, have all been thought to play a part. Sex hormones (estrogen, testosterone) have also thought to contribute to the differences, as hormones may influence the body's responses to renal injury. Estrogen especially may exert certain cellular effects on the kidney because it can suppress the growth of scar tissue as well as affect various growth factors which impact the kidney.

Research Update: Estrogen in Renal Disease
Previous studies using animal models have used hormonal manipulation to explore the effects of sex hormones on renal disease. In these studies, researchers either added supplemental levels of estrogen/testosterone to rats or castrated/performed ovariectomies in males and females rats, respectively. The studies found that estrogen helped to protect against kidney disease while testosterone proved to be detrimental to kidney health.

More recently, Dr. Sharon Silbiger of the Department of Medicine/Division of Nephrology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY and her colleagues examined the direct effects of estrogen on the production of collagens (proteins that contribute to kidney scarring) in the cells located around the small blood vessels of the kidneys (cultured mesangial cells). She and her colleagues found that:

• the female hormone estradiol inhibited the activity of transforming growth factor (TGF-ß); TGF-ß promotes scarring of the kidney in many renal diseases.
• estradiol does this by preventing TGF-ß from activating the enzyme (casein kinase 2) which affects collagen production.
• in this way estrogen reduces the production of collagen in these cultured cells and may reduce scarring in renal disease.

Looking Ahead: Raloxifene and Renal Disease
Silbiger's group is currently analyzing data from a clinical study of the osteoporosis prevention drug, raloxifene. As raloxifene has estrogen-like properties, the researchers hypothesized that raloxifene may affect the progression of renal disease in these women. Broad-based preliminary data from this study will be presented at the APS meeting, but more specific data will be held until the study results are published.

Presentation in Austin, TX
Dr. Silbiger is discussing her work at the conference, Sex and Gender in Cardiovascular-Renal Physiology and Pathophysiology, being held August 9-12, 2007 at the Hyatt Regency Austin on Town Lake, Austin, TX. The meeting is the second scientific event to be sponsored by the American Physiological Society (APS; http://www.The-APS.org) this year.

The American Physiological Society (APS; www.The-APS.org) has been an integral part of the scientific discovery process since it was established in 1887. Physiology is the study of how molecules, cells, tissues and organs function to create health or disease.