Marijuana may affect fertility, study shows

By LOIS BAKER
News Services Editor

Scientists at UB have shown that marijuana-like compounds called ana-ndamides, found in the testis, uterus and oviduct, may play a role in regulating functions of human sperm and influence their ability to fertilize eggs.

The study, to be presented Tuesday in San Francisco at the meeting of the American Society of Cell Biology, shows that human sperm contain receptors for cannabinoids-chemical compounds such as THC, the active substance in marijuana smoke.

Further, the study shows for the first time that cannabinoids can affect three key fertilization processes:

- Inhibition of acrosome reaction, the normal release of the sperm enzymes that enable sperm to penetrate the egg.

- Regulation of very active sperm swimming patterns, called hyperactivation.

- Prevention of sperm binding to the egg cover, or zona.

The findings could have significant implications for diagnosis of infertility and understanding basic human biology and molecular control, said Herbert Schuel, professor of anatomy and cell biology in the School of Medicine and Biomedical Sciences and co-author of the study.

"We've known for 30 years that very heavy marijuana smoking has a drastic effect on sperm production within the testis, which can lead to higher rates of infertility," Schuel said. "Our new findings suggest that anandamides and THC in marijuana smoke may also affect sperm functions required for fertilization in the female reproductive tract.

"The additional load of cannabinoids in the systems of people who abuse marijuana floods the natural cannabinoid receptors and appears to have adverse consequences for reproduction in both males and females."

Pioneering work by Schuel and colleagues previously had shown that sperm from the sea urchin have a recognition site, or receptor, for cannabinoids. They also provided evidence that cannabinoids and anandamides can prevent sea-urchin sperm from fertilizing eggs by preventing the sperm acrosome reaction when they arrive at the egg surface. Washing away the cannabinoids reversed the inhibitory effects.

The current research on human fertilization was carried out in collaboration with Lani J. Burkman, director of the Andrology Section (the study of male fertility/infertility) in the UB medical school, and Alex Makriyannis, professor of medicinal chemistry at the University of Connecticut.

These researchers have found that human sperm contain functional cannabinoid receptors, allowing THC from marijuana, as well as natural cannabinoids (anandamides), to bind to sperm. In 30 trials using modified fertility laboratory procedures, Schuel, Burkman and colleagues incubated pre-screened human sperm in a stimulating medium containing different concentrations of THC or AM-356, a synthetic equivalent of the natural anandamide. Results showed that after six hours, sperm exposed to THC or AM-356 had a 67 percent reduction in premature acrosome reactions, compared to controls.

Motility studies showed that higher levels of AM-356 inhibited hyperactivated swimming, while lower concentrations actually stimulated hyperactivation. In the zona experiments, AM-356 inhibited sperm binding by 75 percent.