Specific protein synthesis in isolated epithelium of guinea-pig seminal vesicle. Effects of castration and androgen replacement

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Abstract
Four intrinsic soluble secretory proteins are synthesized in vitro by isolated seminal-vesicle mucosa from sexually mature guinea pigs. Newly synthesized specific proteins labeled with [14C]glycine and [14C]lysine were precipitated by using double-antibody immunoprecipitation techniques and their radioactivity was assessed. Rates of synthesis were determined on each of 5 days after castration. By 5 days after castration the wet wt of the epithelium decreased to 42% of intact control values; the absolute amount of specific protein synthesized in vitro after 60 min incubation decreased to 28% and the 27,500 g cytoplasmic protein content decreased to 31%. Androgen deprivation leads to a decrease in general protein synthesis in vivo, and to a decrease in specific protein synthesis in vitro. Specific protein synthesis comprised 76% of the total protein formed in isolated tissue from animals 5 days after castration as compared with 99-100% in tissue from intact animals. At 72 h after an injection of testosterone or dihydrotestosterone, seminal-vesicle epithelium wet wt, cytoplasmic protein content and capability for synthesizing specific proteins in vitro were restored to about 70% of normal values. At 72 h after onset of therapy with 3.alpha.-androstanediol, both epithelium wet wt and cytoplasmic protein content had increased significantly, but without a corresponding increase in the capability of the isolated tissue to synthesize specific proteins. The soluble labeled proteins synthesized in vitro by isolated epithelium from intact animals during 60 or 120 min incubation were essentially entirely immunoprecipitable, i.e., specific. In contrast, about 29% of all soluble protein newly synthesized by isolated epithelium from animals 5 days after castration was acid-precipitable, but not immunoprecipitable, i.e., non-specific. The injection of testosterone into castrated animals inhibited the synthesis of the non-specific fraction by isolated tissue. The effects of castration on the ultrastructure of guinea-pig seminal-vesicle epithelium are also presented.