Les molécules de signalisation dans la physiologie et la pathologie testiculaire

Infertility affects an estimated 10% of couples, and in roughly half of these cases the defect can be traced to the men. Male infertility can be due to a failure of spermatogenesis (non-obstructive azoospermia) or to an obstruction (obstructive azoospermia) on deferent ducts. Non-obstructive azoospermia affect about 2% of men, they are due to a failure in spermatogenic maturation. The cause of these defects are still unclear, however, differents causes have been pointed out: genetic defect (Klinefelter syndrome, chromosome Y deletion), physical (irradiation), chemical or infectious affections. But in 40 to 60% of the cases, the cause of non-obstructive azoospermia is not determined. During the last years, from fundamental research, it was hypothezised that an alteration in extracellular signaling systems could potentially caused male infertility. Genetic manipulations show that knock-out or overexpression of some gonadic factors affect spermatogenesis (spermatogenic arrest or tumor formation), for example the systems TGFβ and SCF/c-kit. Experimental data obtained fromin vitro andin vivo approaches show that intratesticular signaling molecules regulate gonadic fonctions with hormones (LH/testosterone, FSH). These local factors might regulate testicular development in the fetal period with the genes of development. Moreover, through adulthood, these local factors could regulate spermatogenesis as a relay of the hormonal action in the testis. Finally, recent studies suggest that abnormalities in local factor expression could lead to testicular pathologies. Futur studies would certainly confirm the important role of signaling molecules in human testicular pathology.