title: Epidermal growth factor increases inhibin synthesis by isolated segments of rat seminiferous tubules.
abstract: The effect of epidermal growth factor (EGF) on the production of immunoreactive inhibin by adult rat isolated seminiferous tubules in vitro has been investigated. EGF (0.1-1000 ng/ml) added to cultures of seminiferous tubules from adult rats caused a dose-dependent increase in inhibin content in the tubules without changing the amount secreted into the media. However, after continuous stimulation with EGF for periods in excess of 5 days, an increase in inhibin secretion was observed. In the presence of 10 and 100 ng FSH/ml, EGF (10 ng/ml) produced a further increment in the inhibin content of the tubules, but this effect was not found with FSH concentrations of 500 or 1000 ng/ml. EGF also increased the tubule content of inhibin after the addition of 100 micrograms dibutyryl cyclic AMP/ml but no effect of EGF was observed on the FSH- or dibutyryl cyclic AMP-induced secretion of inhibin into the medium. The effect of EGF on inhibin content in the tubules was partially suppressed by the addition of 4 beta-phorbol-12 beta-myristate-13 alpha-acetate (20 ng/ml). Insulin (1-100 ng/ml) decreased basal inhibin secretion without changing the inhibin content of tubules and this effect was antagonized by EGF (10 ng/ml) with insulin doses of 1-50 ng/ml whereas, at 100 ng/ml, the effect of EGF on tubule inhibin content was reversed. The addition of EDTA (2 mmol/l) resulted in an inhibition of basal and EGF-induced inhibin production. These data demonstrate a stimulatory effect of EGF on inhibin production by isolated seminiferous tubules which is inhibited by insulin and phorbol esters, both stimulators of protein kinase C activity.
authors.affiliation: Department of Anatomy, Monash University, Melbourne, Victoria, Australia.
authors.forename: G F
authors.initials: GF
authors.lastname: Gonzales
authors.forename: G P
authors.initials: GP
authors.lastname: Risbridger
authors.forename: D M
authors.initials: DM
authors.lastname: de Kretser
mesh_terms: D000818:Animals; D046508:Culture Techniques; D004347:Drug Interactions; D004492:Edetic Acid / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D007265:Inhibins / Q000096:biosynthesis*; D007328:Insulin / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012671:Seminiferous Tubules / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007328:Insulin; D007265:Inhibins; D004815:Epidermal Growth Factor; D005640:Follicle Stimulating Hormone; D004492:Edetic Acid; D013755:Tetradecanoylphorbol Acetate