INTERLEUKIN-1 BIOACTIVITY AND DNA-SYNTHESIS IN X-IRRADIATED RAT TESTES

Stage-specific DNA synthesis and interleukin-1 (IL-1) bioactivity were measured in the rat testis at 2, 6, 12 and 25 days after local irradi ation with 3 Gy to investigate whether there was any correlation betwe en germ cell DNA synthesis during repopulation and IL-1-like bioactivi ty in the seminiferous epithelium. DNA synthesis by intermediate and t ype-B spermatogonia was reduced significantly at 2, 6 and 12 days afte r irradiation in seminiferous tubules at stages II-III and IV-V. IL-1 bioactivity was increased significantly at 6 and 25 days after irradia tion at stages II-VI during repopulation of spermatogonia. At 2, 6 and 25 days after irradiation at stages VIIa-c a significant increase in IL-1 bioactivity was observed that correlated with repair synthesis of DNA. Increased IL-1 bioactivity was also observed at stages IX-XII at 6 days post-irradiation. These observations support the concept that IL-1 is a spermatogonial growth factor which might also stimulate repa ir synthesis of DNA.