TYPE-I AND TYPE-II INTERLEUKIN-1 RECEPTOR EXPRESSION IN RAT, MOUSE, AND HUMAN TESTES

Despite clear indications of interleukin-1 (IL-1) action on Sertoli an d germ cells, previous studies failed to detect IL-1 receptors (IL-1R) within the seminiferous tubules. Here, we investigated the existence of the type I signaling receptor (IL-IRI) and the type II decoy recept or (IL-1RII) mRNAs within the testis. Polymerase chain reaction analys is showed the presence of both receptor mRNAs in isolated rat, mouse, and human somatic testicular cells (macrophages, Leydig, Sertoli, and peritubular cells). While also present in rat and mouse isolated pachy tene spermatocytes and early spermatids, these receptor mRNAs were not found in human germ cells. The distribution of both IL-1R mRNAs was t hen examined in adult rat and mouse testis using light and electron mi croscopic in situ hybridization. No IL-1RI signal was detected in rat testis. In mouse testis, we did not find any signal for IL-1RII. In co ntrast, IL-1RI mRNA was detected in a wide variety of mouse testicular cells. Strong expression was observed in the rete testis area and hig h expression was seen over the epithelium of the epididymal duct and i n interstitial cells, while lower labeling was detected in peritubular and Sertoli cells and in all germ cell types from spermatogonia to ea rly spermatids; no signal was seen in late spermatids. That the IL-IR was also strongly expressed in the interstitium, the rete testis and e fferent duct areas, and the epididymis was established using an autora diography technique. Overall, our study strongly supports the hypothes is that IL-1 is a regulator of testicular function of prime importance .