News Story on Biocompare

geege geege at
Thu Apr 17 23:30:25 PDT 2003

screw biocompare.  i hit "email to a colleague" and they send instead a list
of links, none of which is to the story i forwarded!

here it is, with the provocative quote on rat and human sexuality:

Source: Federation of American Societies for Experimental Biology

How does the body know it has had an ejaculation? And why does it care?
Anatomically, it is more complex than it seems, says the University of
Cincinnati scientist who last year identified the spinal cord cells that
control ejaculation in rats and the neural pathway by which signals travel
between the body's sexual organs to the brain.

At the Experimental Biology 2003 meeting in San Diego, Dr. Lique Coolen
reviews work her laboratory has done in understanding ejaculation and then
discusses her current work in how chemical signals on this pathway
contribute to pleasure and reward, key elements in sexual behavior. Dr.
Coolen is this year's recipient of the American Association of Anatomists'
C. J. Herrick Award in Comparative Neuroanatomy.

Scientists had known for years that there must be a group of cells in the
spinal center that control ejaculation. Following spinal cord injury that
prevents sensation from reaching the brain, humans and other animals remain
able to achieve erection and ejaculation upon stimulation. But the location
of this spinal ejaculation generator remained a mystery until last August
when Dr. Coolen and a postdoctoral fellow in her laboratory, Dr. William
Truitt, reported their findings in Science. Dr. Coolen had targeted the
lumbar spinothalamic neurons in the lower back because these neurons
appeared active only after ejaculation and not during sexual arousal or
mounting. When the researchers used a highly selective toxin to destroy the
thalamic neurons in adult male rats, the rats appeared not to notice. They
continued their sexual interest and behavior, including penetration of the
female. But they no longer had ejaculations, confirming that these were the
cells the researchers had been hunting.

With the ejaculation machinery identified as being part of the spinal cord,
Dr. Coolen then turned her interest to the neural pathway that relayed
ejaculation-related signs from the reproductive system to the brain. This
turned out to be the same spinal cord neural population which in turn sends
ejacultion-related signals to the thalamus. The lumbar spinothalamic neurons
issue sensory signals related to ejaculation that also contribute to
mating-induced activation within brain circuits involved in the regulation
of motivation and reward, the mesolimbic and mesocortical system. Using
neuroanatomical markers and measures of activation of receptors, the
researchers were able to show that the brain released various neurochemicals
during different stages of sexual behavior.

Rats are different than humans when it comes to sex in some ways, says Dr.
Coolen. The male rat can have eight to ten ejaculations over a two hour
period -- with five minute breaks in between –-- before they lose interest
in a receptive female. But, she says, most studies of sexual functioning
have used rodents and the results have turned out to work well in humans.
She hopes other researchers will be able to locate the same cells in spinal
cells in humans and then develop treatments to make it easier for paraplegic
men to ejaculate (important for those men who wish to have families) and to
help the 30 percent of adult males who experience ejaculatory problems
sometime in their lives.

And what about women? Dr. Coolen also is developing research plans to
determine if the same cells that cause ejaculation in men exist in the
lumbar spines of women and if so, what they do.

As for her new work in the pleasure-reward pathways, learning what the
chemical signals are will mean learning ways to manipulate these signals and
treat other sexual dysfunction as well.


-----Original Message-----
From: fork-bounces at [mailto:fork-bounces at]On Behalf Of
Sent: Thursday, April 17, 2003 7:12 PM
To: nest o' geeks
Subject: News Story on Biocompare

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best quote of the day: <Rats are different than humans when it comes
to sex in some ways, says Dr. Coolen.>

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