Gene expression profiles of mouse spermatogenesis during recovery from irradiation

Adult mouse testes were subjected to irradiation with 1 Gy or a fractionated radiation of two times 1 Gy. Testes were sampled every third or fourth day to follow the recovery of spermatogenesis and gene expression profiles generated by means of differential display RT-PCR. In situ hybridization was in addition performed to verify cell-type specific gene expression patterns.Irradiation of mice testis created a gap in spermatogenesis, which was initiated by loss of A1 to B-spermatogonia and lasted for approximately 10 days. Irradiation with 2 times 1 Gy showed a more pronounced effect on germ cell elimination than with 1 Gy, but spermatogenesis was in both cases completely reconstituted 42 days after irradiation. Comparison of expression profiles indicated that the cellular reconstitution appeared equivalent to what is observed during induction of normal spermatogenesis.The data indicates that recovery of spermatogenesis can be monitored by means of gene expression, which could aid in designing radiation treatment regimes for cancer patients leading to better restoration of spermatogenesis.Treatment of cancers often includes radiation and/or chemotherapy and in many cases leads to temporally discontinuation of spermatogenesis. In particular treatment of testicular tumors leads to impaired spermatogenesis. Fortunately, fertility and preservation of androgen production can be sustained in many cases due to reconstitution of the seminiferous epithelia. Side effects of chemotherapy and radiotherapy however include cardiovascular disease, secondary malignancy and a reduced fertility [1]. Current knowledge about re-initiation of spermatogenesis after radiation is however limited, but could benefit the patient's chance of regaining fertility and proper androgen production.Spermatogenesis is a long, complex and finely tuned process [2]; during this process, the developing germ cells are sensitive to endogenous and exogenous stress. Cancer therapies such as radiation and chemo