Hormone therapy appears promising in fighting growth retardation

By Jim Barlow

Mammals malnourished at birth either die or face permanent growth-stunting.
However, full recovery may be closer to reality, based on a series of
nutrition studies involving growth hormone at the UI.

Internationally, malnutrition affects about 100 million children a year and
contributes to 50 percent of the deaths of children under age 4. In the
United States, premature infants and babies with eating disorders are most
at risk for permanent growth retardation.

Sharon Donovan, a professor of nutrition and of pediatrics, and doctoral
student Xiaohui Zhao reported in the July issue of the Journal of Nutrition
that a short-term treatment with growth hormonc enhanced recovery from
neonatal malnutrition. In a subsequent study, to be published in November
in the Journal of Nutrition, they will report that a 100 percent recovery
of body weight can be achieved in malnourished infant rats that were
treated with a combination of growth hormone and insulin-like growth
factor-I (IGF-I).

Growth hormone is secreted by the pituitary gland and is a primary
controller of growth. IGF-I, similar to insulin in structure and function,
is secreted by most organs in the body in response to growth hormone, where
it acts locally to promote growth.

In the studies, the diets of mother rats were reduced to 60 percent of
normal to affect milk production after they gave birth. At day 16, their
pups were refed at normal nutritional levels. The animals received daily
injections of growth hormone, IGF-I alone, or growth hormone along with
IGF-I. Other rats were refed without hormonal treatment.

By day 40, the normally refed pups had achieved about 85 percent of
expected size, but they remained growth-stunted. Those treated with IGF-I
approached 90 percent of expected size. "With the combination of growth
hormone and IGF-I, however, we saw full body-weight recovery," Donovan
said. "Essentially, they bounced back as if nothing had happened."

The combination therapy also sped up the recovery process by about nine
days, the researchers found. "There appeared to be an additive effect,"
Donovan said. "Getting full body-weight recovery so quickly could have
large implications clinically. For a child, it could mean a day or two
difference in getting out of intensive care."

In another follow-up study, Donovan reports that the combination therapy
works because the growth hormone slowed the rate of muscle breakdown. Her
preliminary findings were presented in April at the annual meetings of
Experimental Biology 1995 in Atlanta.

Donovan's research was funded by a Future Leader Award from the
International Life Sciences Nutrition Foundation and the UI. Agricultural
Experiment Station.