STUDY: MARIJUANA USE MAY HURT CHANCES OF CONCEPTION

In a finding that could send shivers down the spines of pot-smoking couples
hoping to conceive, new research is raising the possibility that marijuana
could interfere with reproduction.

New studies show that a cannabis-like compound inhibits the ability of
human sperm to fertilize an egg. Also, high concentrations of THC --- the
psychoactive ingredient in marijuana --- appear to cause structural changes
in sperm as they become ready and able to reach and fuse with a woman's egg.

While pot smoking may not yet qualify as a contraceptive, the findings
presented Tuesday at the American Society for Cell Biology meeting in San
Francisco are some of the first indications that marijuana use could reduce
fertility in both men and women.

Previous research has shown a link between heavy pot smoking and low sperm
counts. The latest study focuses on a substance called anandamide that is
produced by the body and which acts very much like THC on a cellular level.

It is one of a class of substances called cannabinoids that bind to
receptors on cells that also respond to THC. Cannabinoids are found
throughout the body and their affect on various systems is only now being
studied.

In a series of experiments, researchers at the University of Buffalo-SUNY
found that a synthetic form of anandamide reduced by half the number of
sperm that were able to attach to a human egg. Furthermore, high
concentrations of anandamide slowed down sperm's swimming ability, while
low levels kicked it into overdrive.

The researchers also bathed human sperm in solutions containing either THC
or anandamide and found that both substances significantly altered the
normal structural changes sperm go through as they prepare to approach and
bind with an egg.

''For people who are very heavy marijuana users, there may be reproductive
consequences associated with that,'' said Herbert Schuel, a professor of
anatomy and cell biology at the University of Buffalo and lead author of
the study.

More generally, Schuel said, it is possible that glitches in the normal
anandamide system could be linked to some cases of unexplained infertility.