The effects of cyclic adenosine monophosphate, forskolin, and theophylline on motility parameters in gossypol-treated human sperm

Abstract

Objective: To examine the effect of gossypol on human sperm in vitro and the mechanism for the effect.

Design: Fresh sperm ejaculates obtained from normal donors to the University of Kentucky Andrology Donor Program were exposed to gossypol. Motility was studied manually and using computer-assisted sperm analysis. In subsequent experiments, the effects of forskolin, theophylline, and cyclic adenosine monophosphate (cAMP) on sperm motion were measured.

Setting: University of Kentucky Department of Obstetrics and Gynecology Andrology Laboratory.

Main outcome measures: Manual and computer-assisted measurements of sperm motility and motion characteristics.

Results: Gossypol inhibited sperm motility, which could be reversed partially by increasing cAMP.

Conclusion: Gossypol exposure in vitro adversely affects sperm motility in a dose- and time-dependent manner by a cAMP-dependent mechanism.

PIP: The antimotility effect of gossypol on human sperm has been documented. Gossypol is commonly derived from cottonseed oil. The exact mechanism by which this effect occurs is unknown. This paper reports research on the effects of gossypol on sperm motility. Elucidation of the site(s) of action and whether the effects are reversible are also discussed. Fresh human sperm was collected, centrifuged into pellets of equal numbers, washed, and then either overlayered with Ham's F-10 media or treated with gossypol. Gossypol solutions contained 10, 12.5, 20, 25 or 50 mcg/mcl of gossypol. These concentrations were used in measuring the sperm dose-response. Forskolin, theophylline, or cyclic adenosine monophosphate (cAMP) was added to gossypol-treated sperm and motility levels were measured. Motility measurements were conducted manually or via computer-assisted readings of sperm motion characteristics and their actual ability to move. Antimotility effects of gossypol on sperm are related to both dose and exposure time. This study supports the hypothesis that gossypol inhibits cAMP formation. At lower doses of gossypol (10 mcg/mcl), both theophylline and forskolin reversed gossypol's antimotility effect. At higher concentrations (20 mcg/mcl), the effect of gossypol appeared to be rapid and was irreversible. This latter finding has implications for its use as a vaginal contraceptive agent.