Featured Research

from universities, journals, and other organizations

Cause Of Diabetes-related Erectile Dysfunction Is Clarified By Johns Hopkins Researchers

Date:
August 11, 2005
Source:
Johns Hopkins Medical Institutions
Summary:
A new study from the Brady Urological Institute at Johns Hopkins suggests an over-supply of a simple blood sugar could be a major cause of erectile dysfunction in diabetic men.

A new study from the Brady Urological Institute at Johns Hopkinssuggests an over-supply of a simple blood sugar could be a major causeof erectile dysfunction in diabetic men.

Researchers have found that one particular simple sugar, present inincreased levels in diabetics, interferes with the chain of eventsneeded to achieve and maintain erection and can lead to permanentpenile impairment over time. The results, which have implications fornew types of erectile dysfunction treatments targeting this mechanismof erection, are described in the August 16 issue of the Proceedings ofthe National Academy of Sciences.

Previous research had shown that diabetic erectile dysfunctionwas partially due to an interruption in an enzyme that starts the chainof vascular events leading to an erection. The Hopkins team suspectedO-GlcNAc, a blood sugar present in hyperglycemic (high blood sugar)circumstances, to be that interrupting factor.

"We were interested to determine whether high glucose indiabetes mellitus modifies the endothelial nitric oxide synthase (eNOS)enzyme, which is responsible for the achievement and maintenance oferection," says Biljana Musicki, Ph.D., lead investigator of the studyand a research associate in the Brady Urological Institute.

Erectile dysfunction is a common problem for more than half ofmen with diabetes. Musicki says that an estimated "50 percent to 75percent of diabetic men have erectile dysfunction to some degree, [arate] about threefold higher than in non-diabetic men." This is not thesame type of erectile dysfunction seen in non-diabetics, and it is lesseffectively treated with conventional drugs like Viagra.

The study examined rats with type 1 diabetes mellitus as wellas the overall mechanism of erection. "Erection begins when a sexualstimulus activates the enzyme neuronal nitric oxide synthase (nNOS)that causes short-term release of nitric oxide (NO) at the nerveendings in the penis," Musicki explains.

This initial release of NO causes rapid and short-termincreases in penile blood flow and short-term relaxation of the penilesmooth muscle, initiating an erection. The resulting expansion ofpenile blood vessels and smooth-muscle relaxation allows more blood toflow into the penis. This increased blood flow (shear stress) activatesthe eNOS in penile blood vessels causing sustained NO release,continued relaxation and full erection.

O-GlcNAc hinders this normal chain of events by inhibiting theactivation of eNOS, and consequently reducing the release of NO andpreventing the smooth muscle in the penis from relaxing. Without thisrelaxation, there is no shear stress to stoke the production of more NOand therefore, no normal, sustained erection.

The team also found that in comparison with the controls, thediabetic rats' erectile response was 30 percent lower, full erectionswere 40 percent smaller and these erections took 70 percent longer toachieve.

The study emphasizes the reduced blood vessel function presentin patients with diabetes. "The mechanism we describe here stresses thecritical importance of vascular function in the erectile response. Itmay suggest new ways of treating erectile dysfunction by targetingspecifically this mechanism in penile erection," notes Musicki.

Additionally, speaking to more than just the sexual issuesrelated to erectile dysfunction, the research addresses implicationsrelated to the overall understanding of penile health. According toArthur Burnett, M.D., a professor of urology and head of the researchteam, "eNOS plays roles in both immediate erectile response and theoverall health and function of the penile tissue."

Burnett, whose lab has studied penile erection since the early1990s, continues, "the insight here is tremendous because it speaks tofundamental biological and vascular" mechanisms of diabetes. "Thispaper gets back to the physiological relevance of hyperglycemia and howit affects erection. We show here -- using erection as a model -- thevascular damage caused by diabetes and provide insights into vasculardisease beyond this dysfunction," he adds.

The article, "Inactivation of phosphorylated endothelial nitricoxide synthase (Ser-1177) by O-GlcNAc in diabetes-associated erectiledysfunction," appears in the Aug. 16 issue of the Proceedings of theNational Academy of Sciences and was published online Aug. 5. MelissaF. Kramer and Robyn E. Becker, also of the Brady Urological Institute,collaborated on this study.

###

This research was supportedby the National Institute of Diabetes and Digestive and Kidney Diseasesand the National Kidney Foundation of Maryland Professional DevelopmentAward.



Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medical Institutions. "Cause Of Diabetes-related Erectile Dysfunction Is Clarified By Johns Hopkins Researchers." ScienceDaily. ScienceDaily, 11 August 2005. <www.sciencedaily.com/releases/2005/08/050811092706.htm>.
Johns Hopkins Medical Institutions. (2005, August 11). Cause Of Diabetes-related Erectile Dysfunction Is Clarified By Johns Hopkins Researchers. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2005/08/050811092706.htm
Johns Hopkins Medical Institutions. "Cause Of Diabetes-related Erectile Dysfunction Is Clarified By Johns Hopkins Researchers." ScienceDaily. www.sciencedaily.com/releases/2005/08/050811092706.htm (accessed October 1, 2014).

Share This



More Health & Medicine News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Cases Keep Coming for Monrovia's Island Hospital

Ebola Cases Keep Coming for Monrovia's Island Hospital

AFP (Oct. 1, 2014) A look inside Monrovia's Island Hospital, a key treatment centre in the fight against Ebola in Liberia's capital city. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Ebola Puts Stress on Liberian Health Workers

Ebola Puts Stress on Liberian Health Workers

AP (Oct. 1, 2014) The Ebola outbreak is putting stress on first responders in Liberia. Ambulance drivers say they are struggling with chronic shortages of safety equipment and patients who don't want to go to the hospital. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Newsy (Sep. 30, 2014) After the announcement that the first U.S. patient had been diagnosed with Ebola, doctors were quick to say a U.S. outbreak is highly unlikely. Video provided by Newsy
Powered by NewsLook.com
TX Hospital Confirms Patient Admitted With Ebola

TX Hospital Confirms Patient Admitted With Ebola

AP (Sep. 30, 2014) Medical officials from Texas Health Presbyterian Hospital confirm they are treating a patient with the Ebola virus, the first case found in the US. (Sept. 30 Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins