Taka
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 Posted: Thu Jul 31, 2008 5:38 am Post subject: Sugar (geno)toxicity |
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Is it really so bad? All these effect probably also require the
presence of PUFAs and AA ...
Taka
http://www.orentreich.org/Glucose%20Toxicity.pdf
and from http://www.eurekalert.org/pub_releases/2008-07/esfh-dlt070808.php
:
Diabetes linked to male infertility; excess sugars in the body have
direct effect on sperm quality
Diabetes in men has a direct effect on fertility, a scientist told the
24th annual conference of the European Society of Human Reproduction
and Embryology today (Wednesday 9 July). Dr. Con Mallidis from Queen>s
University, Belfast, UK, said that, despite the prevailing view that
it had little effect on male reproductive function, the Belfast group
had shown that diabetes caused DNA damage in sperm.
The increase in the numbers of diabetics diagnosed at a young age has
coincided with worldwide concerns over male fertility, he told the
conference. "But this is not simply a coincidence," he said. "We have
shown for the first time that diabetes adversely influences male
fertility at a molecular level."
The scientists studied semen samples from men with diabetes who were
receiving insulin therapy. On initial routine microscopic examination
the semen samples appeared normal, apart from a slight decrease in
volume.
"But when we looked for DNA damage, we saw a very different picture,"
said Dr. Mallidis, adding that this is not part of a routine semen
analysis. "Sperm RNA was significantly altered, and many of the
changes we observed are in RNA transcripts involved in DNA repair. And
comparison with a database of men of proven fertility confirmed our
findings. Diabetics have a significant decrease in their ability to
repair sperm DNA, and once this is damaged it cannot be restored."
Transcription is the synthesis of RNA under the direction of DNA, and
is the first step towards gene expression, where the information from
the gene becomes a product such as a protein translating the genetic
information into a cellular function. If there are errors in
transcription, there will also be errors in the function of the gene.
"We were particularly interested to see a fourteen-fold decrease in
the expression of a protein called ornithine decarboxylase, which is
responsible for the production of spermine and spermidine, compounds
responsible for cell growth that help stabilise the structure of DNA.
We also found that spermatogenesis 20, a factor unique to the testis
and whose function remains unknown, was greatly increased. Taken
together, these factors indicate clearly that having diabetes has a
direct influence on the health of semen."
Sperm DNA quality is known to be associated with decreased embryo
quality, low embryo implantation rates, higher miscarriage rates, and
some serious childhood diseases, in particular some childhood cancers.
Over the years possible causes for sperm DNA fragmentation have been
suggested but to date the exact mechanism for the damage remains
unknown, say the scientists.
"We found a class of compounds known as advanced glycation end
products (AGEs) in the male reproductive tract. These are formed as
the result of glycation (the addition of sugar)," said Dr. Mallidis,
"and accumulate during normal ageing. They are dependent on life style
– diet, smoking etc – and in many diabetic complications are centrally
implicated in DNA damage. We believe that they play a similar role in
the male reproductive system."
The scientists intend to follow up their work by trying to determine
how AGEs cause and contribute to DNA damage. They believe that they
may have uncovered a new role for AGEs, and that their influence goes
far beyond diabetes and its complications.
"We must now try to develop strategies to protect sperm, and to
diminish the accumulation of AGEs," said Dr. Mallidis. Such strategies
could involve changes in diet, disrupting a step in the formation of
AGEs, or increasing the body>s protection against AGEs, possibly
through the use of dietary supplements.
"Finally, there is spermatogenesis 20. What does it do, how does it do
it, under what circumstances and why? Why is it so greatly increased
in diabetics? We need to find answers to all these questions," said
Dr. Mallidis. |
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