14 DAY TRIAL // The phrase "timing is everything" could get another meaning when it's about sexual attraction.
At least for testosterone production, as scientists have recently found that a protein that controls the bile's production in the liver has double role; one would be that of tuning testosterone synthesis and its action on the testis, biasing the onset of fertility.
Testosterone is responsible for the maturation of the male reproductive apparatus, compassing the testis, epididymis, and seminal vesicles and influencing sperm production. Testosterone overdoses taking place too early during the development of the individual can impair his normal reproductive patterns, making the parents generate offspring too soon to be properly cared for.
David Volle, a postdoc at the University Louis Pasteur in Strasbourg, France, investigated a protein called small heterodimer partner (SHP) while looking for a molecular switch that controls testosterone production.
SHP had been already found to regulate the synthesis of bile in the liver, but its new role is a surprise as it is present in small quantities in the testis. To assess its importance in breeding regulation, Volle's team genetically engineered mice to get individuals lacking functional SHP genes, to draw a comparison between testosterone production and fertility in these mice and in normal ones.
In mice lacking SHP, testosterone levels were higher and the epididymis and seminal vesicles developed faster than in normal mice. Molecular research revealed that SHP appeased a transcription factor protein that hurries testosterone synthesis. The researchers also found that SHP possesses a second role: it decreases the production of retinoic acid, timing properly the sperm differentiation.
Mice lacking SHP matured sexually earlier, mating a week earlier than mice with normal SHP.
There's a lot to be done, but the finding of this new factor in sexual maturity reveals complex pathways. "One day, drugs that interfere with SHP's actions may help improve sperm production in infertile men", said Volle.
Drugs enhancing SHP could be used for treating premature puberty. "Given how little SHP there is in the testes, it is surprising--but believable--to find a molecule that is so influential in the timing of these key aspects of male reproduction," said Bert O'Malley, a cell biologist at Baylor College of Medicine in Houston, Texas. "For male fertility problems, the work has implications for therapies by providing a potential new drug target," he said.