MARIJUANA FIRMLY LINKED TO INFERTILITY

Scientists from the University of Buffalo have smoked out what may
cause some cases of infertility: marijuana.

Today at the annual meeting of the American Society for Cell Biology,
Herbert Schuel and his colleagues describe a cellular signaling system
that responds to THC--the active substance in marijuana--and that may
regulate sperm functions necessary for normal egg fertilization. The
signaling system may be activated by anandamide, a cannabinoid-like
molecule which this study shows for the first time is found in human
seminal plasma, mid-cycle oviductal fluid and follicular fluid.

"These findings suggest that defects in the cannabinoid
receptor-signaling system could account for certain types of
infertility," Schuel says. "A better understanding of these mechanisms
might lead to the development of novel drugs useful in reproductive
medicine. For heavy marijuana users, the study results raise the
possibility they are jeopardizing fertility by overloading this system."

To be sure, the process by which sperm prepare to fertilize an egg in
the female reproductive tract is still mysterious. They must first
become "capacitated" before they can begin swimming vigorously towards
an egg and secrete the enzymes necessary to penetrate the egg's
protective coat, a process called the acrosome reaction.

But Schuel's work shows that both AM-356--a synthetic version of
natural anandamide--and THC affect this sequence of events in three
distinct ways: first, although low amounts of AM-356 stimulate sperm
to swim more vigorously, too much of it has the exact opposite effect.

Both AM-356 and TCH inhibit structural changes over the
acrosome.

And AM-356 significantly impairs sperm from binding to an egg's
protective coat.

"The increased load of cannabinoids in people who abuse marijuana
could flood natural endocannabinoid-signal systems in reproductive
organs and adversely impact fertility," Schuel adds. "This possibility
may explain observations made over the past 30 to 40 years that
marijuana smoke drastically reduces sperm production in males."