In the testis, growth factors and cytokines are synthesized by Sertoli cells and peritubular cells. In different cell types, these mediators are known to regulate the metabolism of extracellular matrix molecules, such as proteoglycans. In this study, we have tested the action of three of these mediators (IL-1 alpha, IL-6 and TGF-beta 1) on the proteoglycan synthesis of rat Sertoli cells. The proteoglycan synthesis was unchanged by IL-1 alpha, nor by IL-6 up to 20 ng/ml, during any maturation stage (14, 21 and 35 days). By contrast, Transforming Growth Factor-beta 1 (TGF-beta 1) enhanced Sertoli cell proteoglycan production from 21 day-old rats, with an optimal response at 1 ng/ml. Kinetic studies showed that the effect of TGF-beta 1 (1ng/ml) was higher after 24 hours of incubation. In presence or in absence of TGF-beta 1, a proteoglycan accumulation was observed in the extracellular compartment between 12 and 48 hours, but this factor did not modify the proteoglycan distribution between cell layer and medium. Furthermore, TGF-beta 1 increased proteoglycan anabolism at all Sertoli cell maturation stages studied but this stimulation was greater for the early maturation stages (14 and 21 days). On the other hand, proteoglycan catabolism was not modified by TGF-beta 1. In conclusion, TGF-beta 1 secreted by rat Sertoli and peritubular cells could modulate, in an autocrine/paracrine way the synthesis of one of the main extracellular matrix components.