'Sperm-stopping' male pill hope
The drug stops developing sperm from maturing
Scientists are developing a male contraceptive drug which stops the
development process of sperm.
Tests on rats show blocking connections to cells which "nurture"
developing sperm makes the animals infertile.
The US and Italian researchers say they used relatively low doses
of the molecule and found no obvious side effects, and the effect
was reversible.
But they told Nature Medicine that work was now needed to see if
their approach is equally effective and safe in men.
High dosage
When sperm are being made in the body in a process called
spermatogenesis they sit next to other cells, called Sertoli cells,
which nurse and help them grow.
If the connection between these two cell types is broken,
infertility can result in men.
In the study authors used a recently developed molecule called
Adjudin to dislodge the developing sperm from the Sertoli
cells.
However Adjudin is also known to be toxic at high doses.
To get round this, the researchers linked it chemically to a
hormone, called FSH, which acts in the testicles where sperm are
made.
The FSH, which the researchers made inactive so it would merely act
as a carrier and not cause any effect itself, delivered Adjudin to
where it was needed, allowing much lower doses to be given.
This made the developing sperm cells "fall off" too early, before
they were properly mature, resulting in complete but temporary loss
of fertility in the rats.
More research is needed to assess if the same approach could work
in humans.
But the researchers, led by Dr Dolores Mruk, from the Center For
Biomedical Research in New York, said: "We anticipate that this
compound could become a male contraceptive for human use."
'Promising' research
Dr Richard Anderson, from the University of Edinburgh, who has been
investigating hormonal male contraceptives in the UK, said: "This
is very promising.
"A non-hormonal approach to male contraception using a drug which
specifically targets a process in spermatogenesis has long been a
very attractive option, as it leaves hormone production by the
testis intact."
He said it appeared the drug effects could be fully reversible,
although only a single dose was given in the study.
"Clearly there are enormous amounts of work needed to translate
this to humans.
"Adjudin may be ineffective in men, as the biochemistry of the cell
junctions it targets may be different, and the precise molecular
basis of its mechanism of action is unknown.
"However, perhaps the most important aspect of this study is the
demonstration that using FSH targeting, drugs that are otherwise
too toxic, can be delivered in safe yet effective doses."
BBC News
