[EDITOR'S NOTE: This story embargoed until Friday, November 7, 2003, to coincide with publication in the Journal of Urology.]
RESEARCHERS PINPOINT POSSIBLE CAUSE OF CHRONIC BLADDER DISEASE
COLUMBUS, Ohio – New research in cats suggests that the cause of some cases of interstitial cystitis (IC) – a chronic and incurable inflammatory bladder disease that affects at least 700,000 women in the United States alone – may lie within the adrenal glands.
In a new study, researchers compared the adrenal glands of house cats with feline IC to the adrenal glands of healthy cats and found that the adrenals in the diseased cats were much smaller – nearly half the size of those in the healthy cats.
"Reduction in adrenal size has also been seen in people with chronic fatigue syndrome, which can occur in conjunction with IC," said Tony Buffington, lead author of the study and a professor of veterinary clinical sciences at Ohio State University. "We don't know why the adrenals were smaller in the cats with IC, but we think that the cats were born with smaller-than-average glands.
The adrenal glands, which sit on top of the kidneys, are responsible for a number of bodily functions, including hormone production and regulation of heart rate and blood pressure. IC affects cats and humans in a similar manner, and urologists believe that the feline urinary tract is one of the best animal models for the human urinary tract.
The researchers also found that, compared to healthy cats, the adrenal glands of the diseased cats produced lower levels of the stress hormone cortisol after the cats were injected with the stress-inducing compound adrenocorticotropic hormone (ACTH). This suggests that the adrenal glands in the cats with IC may not provide an adequate hormonal response during stressful situations.
In humans, symptoms of IC include chronic pelvic pain, inflammation of the bladder and increased urination frequency and urgency. Cats with the disease also have noticeable urinary problems – they strain when trying to urinate and also try to go frequently, often outside the litter box.
The study appears in the December issue of the Journal of Urology. Buffington conducted the research with Jodi Westropp and Kristin Welk, both graduate students in veterinary clinical sciences at Ohio State.
The researchers evaluated how cats responded to an injection of a synthetic form of the stress-inducing compound ACTH. Each cat (11 healthy controls and 20 with IC) was given an injection of 0.125 milligrams of ACTH. The researchers measured cortisol levels in the blood before and after ACTH injection.
The adrenal glands in disease-free cats responded by producing normal cortisol levels after ACTH injection, while the adrenals of cats with IC produced about half as much cortisol in response to the stressor.
"This suggests that adrenal gland function in cats with IC may be relatively normal under unstressed conditions, but it drops during periods of stress," Buffington said.
The researchers also compared the size of the adrenal glands in 21 cats – 13 cats had IC and 8 were disease-free. The adrenal glands of the cats with IC averaged about half the size of the adrenals in the disease-free cats.
If researchers find similar adrenal gland abnormalities in humans with IC, they might be able to develop more effective treatments for the disease. Although cortisol has been tried as a treatment with unsuccessful results, the adrenal gland produces a variety of hormones that could play a role in treating the disease.
"Since the causes of IC are unknown, physicians can only really treat the symptoms, and the disease often returns," Buffington said. "As for cats, not every cat with smaller-than-normal adrenal glands will develop IC, and there are steps a cat owner can take to help prevent the disease from developing, if their pet seems predisposed to IC."
Signs that a cat might be prone to IC include increased sensitivity to its surroundings and also to sudden, loud sounds. Where a cat spends much of its time may influence its chances of developing the disease.
"Cats restricted to indoor living are some five times more likely to develop urinary problems than cats that are allowed outdoors," Buffington said. "I'm not debating whether cats should be housed indoors or outdoors, but owners who choose to keep their cat inside should create an enriched, stimulating environment for their pet.
Boredom may stress house cats, so owners need to make sure their cats have an environment that is engaging and interesting.
Creating such an environment includes providing toys, hiding places and perches for cats, as well as spending some time with the cat every day. Buffington and his colleagues have created the Indoor Cat Initiative program to help owners of indoor cats learn how to create a fuller environment for their pet. Information on the program is online at www.nssvet.org/ici/index.php.
This research received funding from the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases. The Indoor Cat Initiative is supported by a grant from the Kenneth A. Scott Trust.
Contact: Tony Buffington, (614) 292 7987; Buffington.firstname.lastname@example.org
Written by Holly Wagner, (614) 292-8310; Wagner.email@example.com