|Abstract or Summary
- This study was conducted to investigate the distribution
of glutathione peroxidase (GSH-Px) and selenium in
semen of the boar, bull, ram and stallion, and in the reproductive
tissues of the boar, bull and ram. The effect
of repeated noncryoprotective freeze-thawing on GSH-Px
activity was also studied. Both hydrogen peroxide (H₂0₂)
and tetra-butyl hydroperoxide (t-butyl 0₂) were used as
substrates for the enzyme.
Most of the GSH-Px activity in semen of the four species
examined was associated with seminal plasma. GSH-Px
activities in the spermatozoa of these species were comparatively
very low. There were species and tissue
differences in the distribution of GSH-Px in reproductive
tissues. Determined per mg protein, GSH-Px activity was
highest in the testis, whereas the Cowper's gland and
ampulla showed the least enzyme activity. In general,
GSH-Px levels in the reproductive tissues of the bull were higher than, or comparable to, those of the ram. The
reproductive tissues of the boar showed the least GSH-Px
The GSH-Px determined in this study showed a similar
magnitude of response to both H₂0₂ and t-butyl 0₂ and had
a high correlation with tissue and fluid selenium levels.
This demonstrates that the GSH-Px found in semen and
reproductive tissues of the boar, bull and ram is a
Repeated freezing (at -21°C) and thawing, in the
absence of appropriate buffers, led to a decline in seminal
plasma and reproductive tissue GSH-Px activities.
Selenium distribution in semen and reproductive
tissues differed among the species studies. On the basis
of selenium concentration per billion sperm cells, boar
spermatozoa had the highest selenium concentration followed
by those of the stallion, bull and ram in that order.
Bull seminal plasma, however, had more selenium than that
of any of the other three species. The testis and
epididymis had the greatest concentration of selenium
found in the reproductive tissues. Levels of selenium
in semen and reproductive tissues were significantly higher
(P<0.05) than those in blood. The implications of these
findings, as well as the inter-relationship between
selenium, GSH-Px and animal reproduction, are discussed.