To study the role of extracellular nucleosides and nucleotides in the regulation of Sertoli cells, the effects of agonists which occupy A1 and P2 purinergic receptors on aromatase and gamma-glutamyl transpeptidase (gamma-GTP) activities and on transferrin secretion were tested. Sertoli cell treatment with purinergic agonists for a prolonged period of time (72 h) resulted in an increase in aromatase activity under basal conditions. In cultures stimulated with FSH, purinergic agonists counteracted the inhibitory effect on aromatase activity that long-term treatment with FSH promoted. The effects of prolonged treatments with purinergic agonists on the other two parameters of Sertoli cell function were less pronounced. Neither gamma-GTP activity nor transferrin secretion was modified under basal conditions. On the other hand, under conditions where cell differentiation was favored by FSH treatment, reductions in gamma-GTP activity and transferrin secretion were usually observed. The results obtained in dbcAMP-stimulated cultures suggested that A1 agonists exert their regulatory function at the level of cAMP formation while P2 agonists act at a more distal point. The fact that morphological changes induced by FSH were reversed by both types of agonists, while those induced by dbcAMP were only abrogated by P2 agonists, supports this hypothesis. In summary, these results demonstrate that purinergic agonists may be important in the regulation of Sertoli cell function.