from the College of Veterinary Medicine
stories by Jim Barlow, UI News Bureau
of tainted fish curbs adult learning and memory
Since 1992, researchers, led by Dr. Susan Schantz, veterinary biosciences,
have studied Lake Michigan fish-eaters, many of whom regularly had eaten
more than 24 pounds of sport-caught fish a year. The researchers' latest
findings show that the heavy eaters who are now over age 49 have problems
learning and remembering new verbal information.
suggests, for the first time, that PCB body burdens in adulthood may
be associated with impairments in certain aspects of memory and learning,"
Dr. Schantz says. "The focus has been almost exclusively on increased
health risks of exposure to children and pregnant women. It had been
assumed that mature adults are less susceptible than are developing
fetuses. This may not be the case."
were widely useduntil banned in the late 1970sas electrical
insulators and lubricants and as extenders in paints and varnishes.
The chemicals decompose slowly and are virtually non-biodegradable.
Large quantities remain in older electrical equipment still in use.
In the Great Lakes, PCBs make their way up the food chain and accumulate
at increasing levels in fatty tissue.
The findings were
reported in the June 2001 issue of Environmental Health Perspectives,
a journal of the National Institutes of Health. The study also found
elevated levels of DDE (a breakdown product of DDT), lead, and mercury
in the heavy fish-eaters, but the only negative effects were tied to
blood serum levels of PCBs.
high blood PCB levels had difficulties recalling a story told just 30
minutes earlier. They also were less likely than their less-exposed
peers to cluster words given orally into categories based on their meaning
to boost recall, says Dr. Schantz.
the study were from Michigan State University, the State University
of New York at Albany, and the University of Texas Health Science Center
found estrogen role in males might lead to contraceptive for men
Researchers tapping into the estrogen pathway that
regulates fertility in males have found two independent roles of the
hormone, and they may have uncovered a new approach for developing a
Dr. Rex Hess, veterinary
biosciences, and colleagues discovered that estrogen regulates fluid
reabsorption in the male reproductive tract by triggering a protein
involved in sodium transport. They also found that estrogen sustains
the morphological architecture of the efferent ductules.
"We were not
expecting this second role of estrogen," says Dr. Hess. "This
structure-sustaining role appears to be independent of estrogen's molecular
function of regulating ion transport. This tells us that estrogen is
important for the expression of other genes with distinct physiological
and morphological functions."
The overlay of
the double staining of estrogen receptors a and b shows why the efferent
ductule makes a likely target for a male contraceptive.
Dr. Hess and colleagues
had documented in 1997 that estrogen was vital for fluid reabsorption
during the transfer of sperm in fluid from the testis through the efferent
ductules to the epididymis, where sperm matures and is stored. Their
latest publication provides a molecular picture of what estrogen does.
are small tubes that produce concentrated semen. In a series of experiments
using mice lacking the estrogen receptor or proteins thought to be regulated
by estrogen, the scientists showed that when sodium transport did not
occur, excess fluid diluted the sperm, leaving mice infertile. However,
when the estrogen receptor was present, epithelial cells were normal
in appearance, even when sodium transport was abolished in the mice
lacking the protein NHE3.
Hess and colleagues
discovered that NHE3, which is responsible for the transport of sodium
into and out of cells, was directly responsible for luminal fluid reabsorption
under estrogen regulation. "Thus, blockage of the estrogen receptor
could provide a new target for developing the perfect contraceptive
in the male," Dr. Hess says.
The work was reported
in the Proceedings of the National Academy of Science. Co-authors
were veterinary biosciences research specialists Rong Nie and Kay Carnes
and Dr. Benita S. Katzenellenbogen of the University of Illinois College
of Medicine at Urbana-Champaign.
were from the University of Missouri at Columbia, the University of
Arizona Health Sciences Center, the University of California at San
Francisco, and the Human Reproductive Sciences Unit in Edinburgh, Scotland.
The National Institutes
of Health and Kenneth A. Scott Charitable Foundation funded the work.