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A male contraceptive?
MRC News
Scientists may be one step closer to finding a chemical male
contraceptive. Preliminary results on a compound isolated from indigenous plants
look very promising.
Ever since the
revolutionary female contraceptive pill in the 1960s, scientists have been
working on the same for the male of the species, but to no avail. But
preliminary work on a plant extract by scientists at the MRC and the University
of the Western Cape (UWC) might prove to be a step in the right direction.
The plant extract is found
in cloves and also in several Cape indigenous plant species. Mr. Mongezi Mdhluli
of the MRC's Diabetes Research Group's Primate Unit, studied the effect the
compound had on the fertility of rats as part of his M.Sc. degree. "We
found some interesting results in rats. When low doses of this extract were
administered to males, they were unable to impregnate, and the effect was also
entirely reversible - when the dosing was stopped, the males' fertility returned
to normal. Based on these results we decided to extend the study to the African
Green monkey. This now forms part of my Ph.D. study," he says.
They chose the African
Green monkey because research conducted at the Primate Unit has shown this
species to be an excellent model for human reproduction. First tests have
produced similar results to the rat studies: when the male monkeys were treated
with low doses of the compound, they were unable to make the females pregnant.
But the libido of the monkeys was not affected at all and they experienced no
side effects. "This is a very important consideration since men tend to get
very suspicious of fertility regulation. One has to realise that in females only
one oocyte per cycle needs to be prevented from maturing and/or ovulating,
whereas in the male all testicular germ cells need to be stopped from
functioning or one has to render maturing sperm in the epididymis non-functional
in order to induce infertility. So it is important to find something that
doesn't cause permanent damage to the male reproduction tract," he
says.
The scientists are
still researching the exact mechanism of the effect. According to Mr. Mdhluli,
the extract might play a role during the later stage of spermatogenesis (the
process during which sperm is formed). "The membrane of the sperm cells
appear to be damaged, resulting in loss of enzymes which enable the sperm to
penetrate the oocyte" he explains. Beside the contraceptive effect, studies
showed that this compound also had beneficial health effects such as
hepatoprotection, anti-inflammation, anti-tumor activity, anti-hyperlipidemia
and anti-HIV activity. Mr. Mdhluli works under the supervision of Prof. Gerhard
van der Horst of UWC's Department of Physiology and Dr Jürgen Seier of the MRC
Diabetes Research Group's Primate Unit.
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