Urocortinergic system in the testes of normal and cryptorchid dogs.

Cryptorchidism is the most common disorder of the sexual development in dogs, occurring in 13% of the males. Unilateral cryptorchidism is more frequent than bilateral and the right testis seems to be more frequently affected. Urocortin (UCN) is a corticotrophin-releasing hormone (CRH)-related peptide which was observed to affect several functions in male genital organs. The aim of the present study was to investigate the expression of UCN, and its receptors CRHR1 and CRHR2 by immunohistochemistry, Western blot and real-time RT-PCR in the normal and cryptic testis of the dog. The results showed that UCN, CRHR2 and CRHR1 were expressed in normal and cryptic testes. UCN-immunoreactivity (IR) was distributed in germ cells of the normal and cryptic testis. In the normal testis, CRHR2-IR was found in germ and interstitial Leydig cells. In the cryptic testis CRHR2-IR was distributed in gonocytes and interstitial Leydig cells. CRHR1-IR was distributed in the vessel smooth musculature and peritubular myoid cells. UCN and CRHR2 mRNA expression levels were lower in the cryptic than in normal testes. These results suggest that UCN and its receptors might play a role in regulating the spermatogenesis and hormonal activity of interstitial Leydig cells of the dog testis.