Reproduction Abstracts

Introduction: Leydig cells (LCs), the key producer of testosterone (T) in the testis, are affected by various factors such as hormone stimulation. There are various testicular cells that also affect LC function such as testicular interstitial macrophages (TIMs). TIMs are immune factor-producing cells, located adjacent to the LCs, sharing a close physiological and functional relationship. TIMs are associated with development and function of LCs. Ablation of TIMs have shown to impact testosterone production, proliferation and differentiation of LCs in adult rats, suggesting that TIMs are important for LC function. By injecting colony-stimulating factor (CSF; increasing the number of TIMs) at different LC developmental stages, we aimed to establish the role of TIM during LC development.

Materials and methods: Mice were divided into four groups (two CSF or PBS injected-groups were injected for 4 days at the LC proliferating stage (days 29–35)). Groups were culled either at the end of the injecting period (acute effect) or at adulthood (chronic effect). Samples were analysed by immunohistochemistry, stereology, and ELISA.

Results and discussions: Following CSF treatment we observed a significant increase in numbers of resident TIMs in the day 35 testis. There was a significant increase in circulating LH level, with no change in circulating testosterone. These preliminary data suggest that effect of increased TIMs during the LC developing stage by injecting CSF could be involved in modifying the hypothalamic–pituitary–gonadal axis at various points including the pituitary and directly in the testis. Further experiments are underway to elucidate these mechanisms.