Effects of differentiation state and post-castration time lapse on the epididymal response of the lizard to testosterone in vitro: changes in specific protein and mRNA levels

Summary The epididymis of the viviparous lizard secretes large amounts of proteins among which L‐proteins are prominent components. It undergoes great morphological and physiological modifications during its testosterone‐controlled annual cycle. The effects of testosterone on L‐proteins synthesis and L‐mRNA concentrations were studied in cultures of organs regressed after castration. Of three tested serum supplements (2% Ultroser, 10% fetal calf serum, 10% calf serum) calf serum was shown to be essential for androgen‐specific control of L‐proteins synthesis. The duration of castration governed the in‐vitro response to testosterone principally at the level of L‐proteins synthesis. The onset of synthesis was delayed in 2‐month post‐castration explants, compared with l‐month post‐castration explants, and was dissociated from appearance of the mRNA. This suggests that there is translational control of secretory proteins in the regressed epididymis. Conversely, the response to testosterone at the mRNA level was delayed in explants from animals castrated during a non‐secretory state, compared with explants from animals castrated at the onset of secretion. These results, together with other data, suggest that expression of the L‐proteins is under multifactorial control and that the influence of multiple controlling elements varies with the stage of differentiation.