Epidermal growth factor: receptor binding and effects on the sex accessory organs of sexually mature male mice.
The role of epidermal growth factor (EGF) in maintaining the integrity of the male sex accessory glands was investigated in the mouse. In the sexually mature male C3H mouse, EGF levels were highest in the submandibular gland, followed by the seminal vesicles and the prostate. Twenty eight days after sialoadenectomy (Sx), EGF fell below detectable limits in the serum and in the seminal vesicles. However, the prostate still retained 22% of its immunoreactive EGF. There was a seven-fold increase in serum testosterone after sialoadenectomy. Despite this drastic rise in testosterone, both prostatic and seminal vesicular weights were reduced, serum levels of LH were suppressed only by 37% and FSH levels were not altered. All these changes were abolished by the simultaneous administration of exogenous EGF at 100 micrograms./kg./day for 28 days. Both prostatic and seminal vesicular membranes contained binding sites for 125I-EGF. Binding was maximal after one hour of incubation at room temperature. Two classes of binding sites were shown for either organ (Kd = 1.2 nM, n = 56 fmol/mg. and Kd = 74 nM, n = 540 fmol/mg. for prostate; Kd = 0.9 nM, n = 29 fmol/mg. and Kd = 93 nM, n = 150 fmol/mg. for seminal vesicle). The binding of 125I-EGF was displaced by excess EGF and TGF-alpha but not by insulin, ILGF-2 and PDGF. These data suggest that EGF may have an important role in maintaining the integrity of the seminal vesicle and the prostate in the mouse. While the seminal vesicle appears to acquire EGF by uptake from the environment, the prostate may have the ability to synthesize EGF locally.