A growth factor reverses nerve damage in diabetic animals

October 31, 1999

St. Louis, Nov. 1, 1999 -- A recent study reveals that long-term nerve damage in rats with diabetes can be reversed by treatment with an insulin-like protein. Because the damage mimics some of what's seen in people with diabetes, the results suggest that the protein could one day be used to prevent certain nerve complications of the disease.

"You may be able to prevent some diabetic nerve complications, even in people who don't control their diabetes well," says Robert E. Schmidt, M.D., Ph.D. Schmidt is a professor of pathology at Washington University School of Medicine in St. Louis. He also is lead author of an article about the study in this month's American Journal of Pathology.

As many as 60 percent of people with diabetes have some damage to the peripheral nervous system, which receives and sends messages to the hands, feet and other outlying sites in the body. Diabetic neuropathy also can occur in the sympathetic part of the autonomic nervous system, a specialized portion of the nervous system that controls involuntary reflexes. Such damage can produce complications such as irregularities in the control of blood pressure and bouts of diarrhea or constipation.

Nerve cells and their branch-like extensions called axons are vulnerable to abnormally high levels of glucose in the bloodstream that occur during diabetes. In the sympathetic nervous system, the outermost tips of axons swell into doorknob-like structures as a result. These nerve endings allow nerve cells to communicate with each other, and the swelling impedes this process. Schmidt studied the effect of an insulin-like growth factor called IGF-I on diabetic rats. His group examined the animals' sympathetic nervous tissue and determined that the neuropathy mimicked that seen in humans. "The parallels in the pathologic findings in diabetic humans and rats were so strong that we thought that similar processes were at work in rats' nerve cells as in humans with diabetes," Schmidt says.

After the rats had been diabetic for six months -- enough time for nerve damage to occur -- the researchers gave some of them daily injections of IGF-I for two months.

Compared with untreated counterparts, these rats had 80 percent fewer swollen nerve endings in the sympathetic nervous system. And the swelling tended to be less pronounced than in the untreated rats.

Schmidt is quick to note that swelling of nerve endings still occurs to a limited extent in rats treated with IGF-I. But he also has found that healthy rats develop the swellings in small numbers as they age. "A simplistic view is that diabetes might accelerate the aging of sympathetic nerve cells," he says.

He and his colleagues will evaluate the cellular changes occurring in diabetic rats to determine how the swelling occurs. They also will try to determine how IGF-I injections ameliorate the damage.

The growth factor doesn't stop diabetes in its tracks because treated animals are unable to control their blood-glucose levels. IGF-I treatment may instead compensate for the loss of a factor that keeps nerve cells healthy, or it may be a nourishing agent itself. "We have a sense of the potential relevance of the growth factor," Schmidt says. "Now we have to figure out how it works."

Researchers elsewhere are evaluating IGF-I in clinical trials on people with neurodegenerative diseases such as amyotrophic lateral sclerosis, or Lou Gehrig's disease.
-end-
Images of damaged sympathetic nerve cells available upon request. Color image (human with diabetes) and black and white image (rat with diabetes) available, 300 dpi.

This research was supported by grants from the National Institutes of Health. The pharmaceutical company Cephalon Inc. of West Chester, Pennsylvania, provided IGF-I for the study.

Schmidt RE, Dorsey DA, Beaudet LN, Plurad SB, Parvin CA, Miller MS. "Insulin-like Growth Factor I Reverses Experimental Diabetic Autonomic Neuropathy." American Journal of Pathology, 155 (5), 1651-1650, November 1999.

Washington University School of Medicine

Related Diabetes Articles from Brightsurf:

New diabetes medication reduced heart event risk in those with diabetes and kidney disease
Sotagliflozin - a type of medication known as an SGLT2 inhibitor primarily prescribed for Type 2 diabetes - reduces the risk of adverse cardiovascular events for patients with diabetes and kidney disease.

Diabetes drug boosts survival in patients with type 2 diabetes and COVID-19 pneumonia
Sitagliptin, a drug to lower blood sugar in type 2 diabetes, also improves survival in diabetic patients hospitalized with COVID-19, suggests a multicenter observational study in Italy.

Making sense of diabetes
Throughout her 38-year nursing career, Laurel Despins has progressed from a bedside nurse to a clinical nurse specialist and has worked in medical, surgical and cardiac intensive care units.

Helping teens with type 1 diabetes improve diabetes control with MyDiaText
Adolescence is a difficult period of development, made more complex for those with Type 1 diabetes mellitus (T1DM).

Diabetes-in-a-dish model uncovers new insights into the cause of type 2 diabetes
Researchers have developed a novel 'disease-in-a-dish' model to study the basic molecular factors that lead to the development of type 2 diabetes, uncovering the potential existence of major signaling defects both inside and outside of the classical insulin signaling cascade, and providing new perspectives on the mechanisms behind insulin resistance in type 2 diabetes and possibly opportunities for the development of novel therapeutics for the disease.

Tele-diabetes to manage new-onset diabetes during COVID-19 pandemic
Two new case studies highlight the use of tele-diabetes to manage new-onset type 1 diabetes in an adult and an infant during the COVID-19 pandemic.

Genetic profile may predict type 2 diabetes risk among women with gestational diabetes
Women who go on to develop type 2 diabetes after having gestational, or pregnancy-related, diabetes are more likely to have particular genetic profiles, suggests an analysis by researchers at the National Institutes of Health and other institutions.

Maternal gestational diabetes linked to diabetes in children
Children and youth of mothers who had gestational diabetes during pregnancy are at increased risk of diabetes themselves, according to new research published in CMAJ (Canadian Medical Association Journal).

Two diabetes medications don't slow progression of type 2 diabetes in youth
In youth with impaired glucose tolerance or recent-onset type 2 diabetes, neither initial treatment with long-acting insulin followed by the drug metformin, nor metformin alone preserved the body's ability to make insulin, according to results published online June 25 in Diabetes Care.

People with diabetes visit the dentist less frequently despite link between diabetes, oral health
Adults with diabetes are less likely to visit the dentist than people with prediabetes or without diabetes, finds a new study led by researchers at NYU Rory Meyers College of Nursing and East Carolina University's Brody School of Medicine.

Read More: Diabetes News and Diabetes Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.