Pm. Zavos et Pn. Zarmakoupiszavos, THE INHIBITORY EFFECTS OF GOSSYPOL ON HUMAN SPERM MOTILITY CHARACTERISTICS - POSSIBLE MODES OF REVERSIBILITY OF THOSE EFFECTS, Tohoku Journal of Experimental Medicine, 179(3), 1996, pp. 167-175
Gossypol (GOS) is a polyphenolic compound derived mainly from cottonse
ed oil, which has been found to have anti-fertility effects in males.
It has been reported to induce disturbances of the hypothalamicpituita
ry axis, disruption of spermatogenesis in the testes, and inhibition o
f postejaculatory spermatozoa motility. The inhibition of human sperm
motility by GOS has been documented both in vivo and in vitro, althoug
h the exact mechanism and possible reversibility of such inhibition is
unknown. The objectives of the present study mere 1) to examine the i
n vitro dose response of human sperm motility to GOS, and 2) to determ
ine if the motility inhibition of GOS was reversible, using agents whi
ch alter the second messenger cyclic adenosine monophosphate (cAMP), s
uch as, 8-bromo-cAMP (8-Br-cAMP), and forskolin, and adenylate cyclase
stimulator. Fresh spermatozoa were obtained from males of known ferti
lity. Motile spermatozoa mere recovered via the SpermPrep(TM) (SP) met
hod and used further in all experiments. Quantitative and qualitative
sperm parameters were recorded at collection, post-SP filtration and p
ost-treatment. Motile spermatozoa were resuspended in either media (SP
), or in increasing concentrations of GOS (10, 20, 30 and 50 mu g/ml)
as gossypol acetic acid in media. To study the possible reversibility
of the GOS effects, spematozoa already exposed to GOS for 2 hr (at the
concentrations mentioned above) mere centrifuged and reconstituted in
media containing either 10 mM 8-Br-cAMP or 100 mu M forskolin and mea
surements of percent motility and grade of motility (0-4) were taken a
t 0 time and at 30 min intervals for a total of 2 hr. Each experiment
was replicated 8 times. The results obtained in this study showed that
GOS inhibited sperm motility in a dose and time dependent manner. The
motility characteristics of the 50 mu g/ml GOS group were lower than
all other groups (p< 0.001) and the spermatozoa were completely immobi
lized within 60 min. Cyclic AMP somewhat rescued the GOS-treated sperm
, whereas exposure of GOS-treated sperm to forskolin had no such effec
ts. The data generated in the present study suggest that GOS inhibits
cAMP formation, which subsequently decreases sperm motility characteri
stics. At low concentrations (up to 20 mu g/ml for 30 min), GOS inhibi
tion is reversible and compounds that act to increase cAMP seem to be
partially responsible for the reversal of GOS inhibition. However, GOS
inhibitory effects at levels higher than 20 mu g/ml (exposed for 30 m
in) mere impossible to reverse, which suggest that GOS at those levels
could be an effective agent for vaginal contraception.